16th Century Amber Varnish & Venetian Amber Varnish -- Amber Varnishes available during the 1500-1600's

Amber varnish has a long history of practical use among craftsmen, including visual artists. During the Renaissance, oil painters throughout Europe popularly used amber-based oil varnishes made commonly in Germany ; but other countries also made amber varnish. Few artists would even dare the dangerous process, preferring to leave that to the varnish-makers. According to the old recipes found in various manuscripts, locally-mined Baltic Amber was first fused (melted) alone under great heat then cooled by pouring the hot mass onto iron plates. Collected for use, this Amber 'rosin' was splintery and soft but still difficult to dissolve, requiring the heating of itself and a quantity of oil --typically, an oil cooked with litharge --to a temperature of around 650 degrees F. for total incorporation. Some old recipes often mention an amount of turpentine being added upon cool down. [A spirit varnish could be made by dissolving the Amber "rosin" in an essential oil, such as hot turpentine, but this was not the common amber varnish.] Because of the high-heating, the amber varnishes made commercially were known to be darkly-colored, and this caused some painters to decry their use, or use them only with the dark colors. However, experienced painters found that a mere drop of the amber varnish was all that was necessary to give handground paint better binding ability, proper painting character, as well as supplying much greater durability.

Fast-drying VS slow-drying amber varnish

As mentioned, amber varnishes were often made with oil which had been cooked with some sort of drier. This type varnish was usually cloudy and even darker than normal amber varnish; however, due to the drier, this varnish dried within one or two days and without the need for placing the work in direct sunlight-- which is a time-won method of speeding the drying of oil-paint and oil varnishes. Thus, as an object coating--such as musical instruments-- these varnishes held favor over the pure unleaded amber varnish. One drying-type amber varnish produced in Italy was prized there (see the report on Orazio Gentileschi and his amber varnish). This varnish was generally known as "Venetian amber varnish". Another and very similar amber varnish was made in Germany. This was simply referred to as "German amber varnish" [Venice was a center for the amber trade ; Germany mined /produced amber. ]

Though rather dark and red-ish, the German or Venetian amber varnishes were readily adopted by lute-makers desiring the toughest and tack-free coating for their fine craftsmanship. The coatings of amber were built up in thin layers, adding an orange-brown character and glow that could take the highest polish. But some oil painters utilized these varnishes, too. As only a mere drop or so of this powerful varnish was necessary to make walnut-ground paint behave nicely under the brush, the dark color did not sway or matter (plus, any slight tinge simply bleached out upon drying).

Our Amber varnishes

We offer amber varnish in both a regular straight varnish as well as a faster-drying version. Both varnishes are made using Baltic amber.

Our 16th Century Amber Varnish is made using walnut oil and is not cooked with drying agents. It represents the very cream of the crop as regards amber strength. Applied in thin layers, our 16th C. AV will dry-to-touch in 3-4 days ; or overnight if it's given a short sunbath. When added to oil paint, or when using this varnish to make mediums, no difference will be found in usual drying times.

We also offer the equally-historic Venetian Amber Varnish, which is capable of drying overnight to a tough coating. Unlike our 16th Century version, our Venetian Amber Varnish is cooked with a drying agent. Thus, it is a noticeably darker production. But artists may still easily and readily use it. When added to oil paint, overall drying is expedited through use of this Venetian amber varnish. This particular varnish seems to have held strong favor with all sorts of craftsmen. According to the olden writings, an amber medium composed of two or three parts walnut oil to one of this Venetian Varnish was commonly used by Artemisia Gentileschi and others in Italy during the early 1600's.

Our 16th Century Amber Varnish is amazingly light in color and perfectly clear. It contains a large amount of Baltic amber--the highest available anywhere today--dissolved nearly in its most perfect form, allowing very little loss of its original constituents ; and this then combined with an equal amount of a high-temperature non-yellowing heat-polymerized walnut oil. Held to the light, 16th C. AV is perfectly clear and glows with a yellow-orange cast. A droplet is nearly the same color as a light cold-pressed linseed oil. It will not discolor whites. These rare characteristics are achieved by using a unique and well-practiced cooking method developed through many trials ; and one that virtually eliminates the darkening effects of carbonization. I suspect there were producers of the old varnish who also knew of these techniques which allowed artists a more perfect version to that darker most-common amber varnish sold generally as a wood-coating varnish. 16th C. AV results in very crisp paint as it performs a congealing effect when added in slight amounts to oil paint. This makes it nicely suitable for working with either solvents or the use of regular (or even poly-type) oils. For making mediums, this varnish can be greatly thinned with oil --even standoil (for tube paint-users). [ For those who wish the lightest and clearest amber varnish but also desire faster drying, this varnish can be made so by the addition of a preferred drier, such as our unique and safe 19th Century Siccatif de Courtrai.]

As for our Venetian Amber Varnish, it is a darker varnish but still easily incorporated with oil painting. Orazio Gentileschi and other artists would add a droplet of the Venetian amber to their paint ; but then also either purchase (from the local color shops) or personally construct a medium in their studio by simply combining the amber varnish with two or three parts of walnut oil as an oiling-out agent. Our Venetian Amber Varnish performs well when added in one or two-drop amounts to handground paint (or commercial tube paint). Also note: our Venetian Amber Varnish is linseed oil-based.


Our varnishes should generally be used in either of two methods. (1) The varnish is used pure as a one, two, or, depending on the quantity of the paint, more drops additive to the paint nuts, or, (2) The varnishes are mixed with one, two, or three parts walnut oil to make a medium (the more oil, the softer the brushing, though a crispness remains due to the amber varnish ingredient). Depending on need for "set", turps may or may not be utilized. Note: it is perfectly proper to add turps when desired for certain manipulations or to promote "set". ["Set" allows overpainting with fresh paint soon after the solvent evaporates from the previously-applied paint; this is a manner of gently applying fresh paint layers without need of firm drying between them.]

Both our amber varnishes can also be utilized to congeal oil paint on the palette ; then the work is performed by means of solvents ; either the solvent mixed readily into the treated paint to make it creamy and facile with no need to 'oil-out' the ground or underpaint ; or the brush is first dipped into solvent then into the paint, thinning as needed 'on the fly', so-to-speak.

Below: Our amazing 16th Century Amber Varnish is made by dissolving pure Baltic amber and combining it with an equal quantity of non-yellowing heat-polymerized walnut oil (50% amber to 50% oil). This image shows how much amber (bottle at the right) is used to make a full 80 mil. bottle of this varnish (bottle at left). Due to this concentration, a very little of this varnish goes a long way. This heavy yet clear and pure concentration of Baltic amber in oil is unique to the realm of amber varnishes.

Historical Information

We hold the "Old Masters" in high reverence today for what we think they knew about the perfect methodology of oil painting. But, apparently, judging from the rare writings that have come down to us, these oil painting masters were stumbling around in the dark as much as we are today. Contrary to beliefs we now hold, there was no universally recognized or accepted perfect painting methodology. Obviously, the better techniques have "arrived" rather safely to our time-- though we cannot always know the hand of restoration to an affair, some many works do seem to be in wonderous condition; of course, we should pay most of our attentions to these particular works regarding their original means of execution.

For one example of technique contention, especially fitting this brief about amber varnish, there was great controversy during the Renaissance among painters as to use and method for use of resins. Of course, historical writings make it very clear that resins were often utilized in painting technique. Paint can certainly be made from oil alone but this stuff is not to my own liking; though it may appear like paint, it is either too stringy, or slumps within an hour of compounding, or manifests several other nuances I find troublesome to my method. And so, to get the paint character I desire, I must give my handground paint an additive to make it do my proper bidding. In this regard, I have often resorted to resin-use in a wide variety of forms.

Historically, resins were utilized in one of two ways; either as a resin dissolved into boiling hot oil, like Linseed oil, to make an oil varnish (like amber varnish); or as a resin dissolved within an essential oil, like turpentine, to make a spirit varnish.

Considering amber varnish, we find an excellent example of its being in use, at least as a varnish for coatings, in the 12th Century; Theophilus the monk gives a recipe for making it; and it is not inconceivable that this recipe was also known to the Romans.

Eastlake went to great lengths in trying to show amber being used by van Eyck; but who can really say for certain? Many recipes appear in the old writings showing a widespread usage of amber varnish during the 1400-1600's, and there is some mention of it being prescribed for use with oil colors (for instance, the physician known as DeKetham gives formula and direction for its use as such in his 1500's manuscript).

Oil varnishes were the primary types known up until the 1550-1600 's time frame. At that time, a steady increase in spirit varnishes began and eventually took over. This time of spirit varnish use lasted until the beginning of the 19th Century, gradually turning in favor of the oil varnishes again in the later half, and came back again to spirit use during the 20th Century. It is still with us today, with many, including science, railing against oil varnishes as certain destructors of fine oil painting craftsmanship. [ BTW, last I read, science has yet to give affirmation to the possibility of even dissolving amber into oil.]

One thing a review of the historical does show is this: according to writings from the 20th Century concerning the cleaning and restoration of old oil works, it would appear that a trend towards weak or easily dissolved oil paintings began to crop up in the same time period of spirit varnish-use and its wide acceptance -- and, importantly, this is before the instance and use of wax during the 1700's and beyond ( there is no mention of wax being used in the 1600's; but perhaps I should best say, I have never come across any.)

The following small 18x24 work entitled "Sandstone Majesty" was painted from start to finish with a medium constructed with amber varnish in a 1:2 mix with unrefined walnut oil.

TheTrouble Begins

I know from various 1600's time-period manuscripts of certain oil painting masters preferring either the oil varnishes or the spirit varnishes. For instance, Orazio Gentileschi, J. Michael Wright, Mario De Fiori, and others maintained a then-popular belief in the use of oil varnishes -- typically Amber varnishes. These artists used a drop or so of oil varnish in their rubbed-up colors as well as oiling out layers over dried underpaint to allow easy and further overpainting. The method is obviously a sound one; after nearly 400 years time, and though I am uncertain about De Fiori, the other's works have come down to our time in excellent condition. [ For a review of the excellence in Gentileshi's works, the Getty Museum has three examples that have apparently never suffered the need for restoration attempts-- except for varnish-removal. Additionally, I am made aware through my correspondence with the figure painter James Morton of there being a Wright portrait in the Columbus Gallery of Ohio that appears to have been, in Mr. Morton's words, "painted yesterday".]

In total opposition to use of oil varnishes, however, other painters of the time, like Geovanni A. Canini (not to be confused with Cennini) considered all oil varnishes as inherently bad. I know this for fact because Canini had a long visitation by one Richard Symonds who traveled extensively in Italy within the first half of the 1600's. Symonds recorded many observations about Canini's methods in his notebooks. [Symond's manuscript, titled MS Egerton 1636, can be reviewed in a book of a PhD Thesis by Mary Beal, "A study of Richard Symonds", University of London, 1978 (my especial thanks to James Morton for making me aware of this interesting dissertation).]

Canini told Symonds that an oil varnish addition caused his (Canini's) white to become browned outright. Of course, we might assume this is in reference to the dark color of the commonly available and utilized German Amber Varnish, or the Venetian amber varnish. Canini strongly maintained the use of such dark oil varnishes with oil paint would cause all works to blacken in time. The oil varnishes aside, Canini did regard resins in the form of spirit varnishes of valuable service to his own work. The spirit varnishes most used in Italy at the time were made from Mastic, Sandarac, Venetian turpentine, or Strasbourg turpentine. These spirit varnishes, most of them very light in color (as opposed to the darker Amber oil varnishes), were increasingly used during the later 1600's and beyond, as isolating layers inserted between usually straight and simple dried oil-and-pigment paint. This isolation layer refreshed the dried paint and usually allowed easier overpainting.

From a reading of Symond's notes, it is plain Canini and others used spirit varnishes in the same ways that many oil painters still do today, i.e., as a final protective and glossy surface-coating. However, Canini was also fond of the aforementioned other use for the spirit varnishes, i.e., as a retouch varnish applied over dried underpaint and used for expediting further over-painting. As such, this spirit varnish left its nearly pure resin-constituent actually within the painting-- not just upon its surface as an easily-removed coating. As noted above, such use of a spirit varnish allowed Canini easy overpainting with another superimposed paint layer (Canini preferred Sandarac and Mastic varnishes for this purpose).

I am not personally acquainted with the curent condition of Canini's works. However, Beal notes in her dissertation (page 66) that most of Canni's surviving oils are in poor condition, though one that had recently been restored was more attractive. I do know a history of painting, and it would appear from what I know that the use of spirit varnishes as isolating (retouching) layers within an oil painting may not be a good thing. It would appear the paintings undergoing restoration today and made within and since this time period are often noticeably more prone to solvency by the conservator's chemicals. Could there be a connection between this widespread fragility and the use of spirit varnishes within the actual paint-layers?

I know of the principle of fat over lean. But I am also aware the sudden insertion of a spirit varnish layer between two oil paint layers will, as it's function describes, ISOLATE and thus interfere or negate the proper fat-over-lean method. Though such a layer of resin will refresh dull coloring and does often make continued overpainting easy of application, this substance is neither fat nor "lean" of fat. It contains no fat; it is purely a mechanically slick, brittle, and likely forever easily dissolved substance inserted between oil paint-layers (fat). In time, the oil-overpaint may possibly shrink upon this pure resin-layer and allow fissuring to begin. And if not fissuring, the common microscopic cracking will certainly occur soon enough. Of course, any slight fissuring or microscopic cracking will allow the underlying spirit varnish-deposited resin layer to be open to attack from the solvents in use by our modern day restorers when cleaning the painted area of old varnish. Thus, everything above that original spirit isolating layer will want to dissolve or lift as the cleaning solvent attacks and "rejuvinates" the old spirit varnish-layer, turning it to a liquid form again. Needless to mention, as exhibited by Orazio Gentileschi's known manner of painting, this would not be a problem if an oil varnish like Amber had been used instead.

I have noted this effect of fissuring to be ever-so-common in many 17th-19th century works. Where the underlying paint is in good shape and the overlaying paint is fissured, I could suspect the use of a spirit varnish layer as the causal culprit (aside from perhaps a poorly dried underpainting, or nefarious never-drying paints --such as bitumin, VanDyke Brown, or Cassel earth).

The Rest of the Story

By the late 1600's, amber varnish was "out". Spirit varnishes were in. Copal varnish seems to have replaced amber as a more easily produced and lighter-colored varnish. I am not completely certain who might still have been making amber varnish by the mid 1700's, but I do know some experimentalists began to review history and there were attempts to recreate and re-introduce the old oil varnish to artist's use. For instance, there is the worthy work of two Europeans, Hoffmann and Zeigler, who produced good amber varnish around 1760 by cooking the resin under pressure.

Then there is the interesting Mr. Sheldrake, an Englishman attempting to prove the benefits and historical use of amber varnish. Mary P. Merrifield made good mention of this fellow within her 1849 review of numerous manuscripts written during the Medieval and Renaissance periods.

Quoting Merrifield: "The use of amber varnish as a vehicle for painting was revived and recommended as long ago as 1801 by Mr. Sheldrake in a paper published in the 19th volume of the Transactions of the Society of Arts. In these papers Mr, Sheldrake endeavours to prove that this varnish was used by the Italian painters; and as his opinion has been in a great measure confirmed by documentary evidence, his papers acquire additional interest from his having recorded the experiments made by himself in painting with this varnish. The result of Mr. Sheldrake's experiments is thus stated:"

[Sheldrake] " I dissolved it [amber] in each of the painter's oils, by Dr. Lewis's process, without injuring its colour; and this solution was made in the common way. It was much darker coloured in itself, but produced scarcely any difference in effect when mixed with colour. By experiments with each of these solutions I ascertained the following facts, viz.:

" Every colour, and all the tints compounded from it, were more brilliant than corresponding tints and colours mixed with the best drying oils to be procured from the shops."

" Colours mixed with amber, after having been shut up in a drawer for several years, lost nothing of their original brilliancy. The same colours tempered with oils, and excluded from the air, were so much altered that they could scarcely be recognised.

" Colours tempered with amber were laid on plates of metal, and exposed (both in the air and close boxes) for a long time to different degrees of heat, from that of the sun in summer to the strong heat of a stove, without being injured. It is needless to observe that oil-colours cannot undergo the same trials without being destroyed.

Alright, let's stop a moment. Sheldrake's assertion is perfectly borne-out by my own 1998 and 2001 darkness tests. In both instances I placed my various mediums and varnishes on acrylic-primed mattboard, allowed them to dry; then stored the tests away in a completely darkened 2nd floor closet. Throughout the years I would occasionally pull out these tests for notes. In the case of my copal and amber varnishes, no yellowing beyond the initial color of the fresh varnishes occurred. None. I here present images showing the current 2016 appearance of my earliest 16th Century Amber Varnish as it comes directly from that dark closet. I'll point out that amber varnish is a naturally yellow varnish due to the yellow nature of the amber, itself.; thus, when used as a coating varnish, it must be applied in a very thin manner, which I will cite later in this essay.

After 17-years in the dark closet, the 16th C. Amber Varnish has not darkened in the least. Also, notice the second sample on the right where an early 'tubed version' of my Amber Gelling Oil (a varnish) was mixed with raw walnut oil. Witness how that sample has yellowed. That's not the fault of the Amber Gelling Oil. No. That yellowing is due to the raw walnut oil I mixed with the AGO so as to create a jelly medium. Realize, all commonly pressed traditional drying oils will sallow in darkness. Linseed performs the worst in this trait. In fact, linseed oil will actually sallow in normal room-lighting, causing what is known as a "gallery tone".

In the second test, my 16th Century Amber Varnish was given a small addition of a treated drying nut oil, which had a faint though very nominal yellowing effect.

Again, here is proof that amber varnish -- made the correct way -- will not yellow in darkness, that is, unless some common drying oil is added to it. The drying oil yellows; not the amber (or copal) varnish.

So you see? Sheldrake was correct. When pure amber varnish is used as the sole binder for pigments, the paint created will not darken as would happen if regular oils were used.

Sheldrake continues:

" These colours, when perfectly dried in any way, were not acted upon by spirit of wine and spirit of turpentine united. They were washed with spirit of sal ammoniac and solutions of potash for a longer time than would destroy common oil-colours without being injured.

" They dry as well in damp as in dry weather, and without any skin upon the surface. They are not liable to crack, and are of a flinty hardness; whence it appears that this vehicle possesses every desirable property, and it is presumed may be a discovery of some importance to artists."

" Having succeeded thus far with amber, I tried the same experiments upon solutions of gum copal, which is nearly as hard and insoluble as amber itself. The result of these was the same as the former, except that I with copal the colours were something brighter than with amber. As it is extremely troublesome to dissolve the copal and amber, I tried those solutions of them in oil which are sold in the shops. When good I found them to answer as well as my own. This is a great convenience, as many might be deterred by the difficulty of preparing this vehicle, who may willingly use it, as it is thus to be procured without that trouble."

Mr. Sheldrake also observes: " If my experiments have not misled me, I am entitled to draw the following conclusions from them :wherever a picture was found possessing evidently superior brilliancy of colour, independent of what is produced by the painter's skill in colouring, that brilliancy is derived from the admixture of some resinous substance in the vehicle. If it does not yield on the application of spirit of turpentine and spirit of wine, separately or together, or to such alkalies as are known to dissolve oils in the same time, it is to be presumed that vehicle contains amber or copal, because they are the only substances known to resist those menstrua."

" I have been told, and some experiments of my own prove the information to be true, that the Venetian pictures, considered with respect to vehicle, are of two kinds: for some are extremely hard, and not at all affected by any of the above menstrua; others are similar in colour, but so tender that it is scarcely possible to clean them without injury, and in that respect are little superior to turpentine colours. The first, in consequence of the data which I have laid down, incur the suspicion of being painted with amber or copal."

Commenting on Sheldrake's discourse, M.P.Merrifield added these words: "The correctness of Mr. Sheldrake's observations will be acknowledged on comparing them with Mr. Eastlake's remarks on the advantages of amber varnish as a vehicle for painting. The firmest and most durable varnishes were undoubtedly those composed of amber and oil ; the next were those composed of other resins, such as sandarac, mastic, and pece Greca, with oil, or of amber or copal dissolved in a balsam; and the last class, which consisted only of resins dissolved in essential oils, was decidedly the least durable."

Thanks to Eastlake-- who again promoted use of oil varnishes, especially copal and amber, in his 1848 "Methods and Materials of Painting of the Great Schools and Masters"-- as well as others, like his precursor, Sheldrake, amber and copal oil-type varnishes were once again adopted for use by oil painters. Of course, there are great works among us today as testament to such use -- see Gerome for example. This re-introduction --though it was far from universal-- lasted about 60 years and began dying off as — amazingly, authorities like Max Doerner began touting the use of spirit varnishes again; and with the very same old paint-softening results [see Helmut Ruhemann's "The Cleaning of Pictures", Faber & Faber, London, 1968, wherein he notes cleaning experiments on Doerner's student's works and found easily dissolved paint— the same condition alluded to by Sheldrake when mentioning the soft, weak paint encountered during the cleanings of many 1600's works. While Ruhemann's findings should not be considered 100% scientific proof covering all considerations, still, they show that perhaps something was amiss under Doerner's direction. BTW, Eastlake was also a painting restorer and had much experience with the cleaning of old master works.]

Why do we do this, time and again? Do we as artists simply strive to be unique, to go our own way and seek new means over the tried and true? Quite possibly so. In my own case, I was looking for something different when I met up with amber.

Then again, maybe it's because our current science has not stepped in to "substantiate" the apparent gleanings from the historically-written word. I often come across modern assertions maintaining amber varnish to be detrimental to oil painting. I wish to make it clear, modern science has not tested the value of amber varnish. The fact is, for the past 100 years, modern science has maintained it to be impossible for amber to be dissolved in oil ; and that amber varnish is a scam — a pronouncement I must hold as amazingly naive. As noted earlier, Theophilus in the 12th Century gave perfect directions for making it. The Germans and Venetians produced it in large amounts during the 1500-1600's. Hofman, Zeigler, then Sheldrake also showed it could be made. Yet the paint chemists of the 20th Century could not recreate the means to doing the simple same. [As recent example to this continuing belief, I recall in 1998 reading on the Sinopia forum the words of a conservator admonishing readers that there was no such thing as amber varnish. ]

And so, even with no actual scientific studies available, amber and copal varnishes are credited with all sorts of problematic effects when used within oil paint. Where do the authoritative negative decrees come from? In our time, I think they derive mostly from R. Mayer's well-known book ; and, of course, preceding him, Doerner's well-read manual had few good words for any oil-based varnish. My own attempts to get to the bottom of the whole debacle have led me to pronounce the primary culprit to most problems associated with oil painting to be use of spirit varnish as cold additions to paint, and, very important appearance-wise, the use of linseed oil, which is likely the primary reason why anything and everything containing it --including megilp-- may go dingy or wrinkly in due time.

Linseed oil a problem-maker? I will say yes. It is now my own experience that, in just about every situation where problems arise and are blamed on mediums and driers, the underlying culprit-cause is the linseed oil ingredient; and this causality being linseed's penchant to yellow or brown when it reaches a certain stage of drying. What I mean is, whenever I have substituted walnut oil for the linseed, the same problem either did not occur, or was barely noticeable.

Below is an image comparing a commercial artist's best CP linseed oil, foots-separated unrefined walnut oil, and foots-separated flaxseed oil. All oil paint piles were compounded exactly the same way with lead carbonate and placed flat in a daylight-lit room. The nut oil in the center dried the fastest (4 days) and did not collapse into itself, wrinkle, nor turn yellow, as did both types of linseed oil.

This is not to say fine oil paintings cannot be created with linseed-based colors. Certainly they can. But do not compound your paint with much linseed oil; and expect a "gallery tone" to overcome the work soon enough. And when you add a drier, realize the faster oncoming yellowing is due to the linseed oil simply reaching its yellowing stage sooner than otherwise; and especially if the drier has been itself concocted with linseed. The same will occur with many oil varnishes made with linseed. Of course, history does seem to show, as in the case of the younger* Van Dyck and others, that if certain precautions are made and a knowing technique is utilized, linseed oil can be the basis to great painting. Yet, I think it can be ultimately shown walnut surpasses linseed in nearly every way ; as such, I promote its use.

[Note: DeMayerne recorded in his manuscript (entry dated1632) Van Dyck's own words that he used only linseed oil. However, a bit later in Van Dyck's rather short life, his students (Soest, Gandy) wrote that their master used walnut oil for his paint and mediums ; and so, it would certainly appear the master experienced a change in his thinking.]


Historical technique has indeed come down to us in the form of many time-capsule paintings maintaining excellence of surface and the perfection of oil-painting. 400 years is a long time; this particular 'oil varnish versus spirit varnish' argument has gone on long enough. I believe Geovanni Canini was (obviously) wrong about O. Gentileschi and what Canini referred to as the then-popular use of oil varnishes; Gentileschi's and Wright's paintings are found in excellent condition today. These painters valued the use of oil varnishes-- and so should I.

There is broad evidence which tells me that it is the oil varnishes applied as repainting mediums (termed "oiling out" mediums) which allowed ease of overpainting without the eventual fissuring. Spirit varnish isolating mediums should be avoided perhaps altogether. Instead, one merely waits until the first paint layer is dried to touch, then gives a thin coating of the oil varnish medium to the area before overpainting. There should be no isolation between layers of oil paint, unless that isolating barrier contains as much fat as the paint-layer below and above it; this would mean an oil-type barrier-- never a spirit-varnish type. [I do not address the matter of using Balsams combined with oil herein....though I have reason to suspect the use of small amounts of Coniferous Balsams added to mediums and oil paint may be a valuable and very lasting practice.

As for the still common practice of mixing spirit varnishes with oils to make lightly-colored mediums, I have done little work with this. There is talk today of eventual cross-linking and a better bond between cold-mixed resins and oils through the agent of time. It is a kind thought that perhaps soft resins in spirit-liquid form mixed cold with oils will co-habit and cross-link on a molecular level and thus become insolvent and tougher over time.... but I wonder over this. From what I know about oil varnishes and their make-up, it takes a terrific heating to perfectly combine any resin with a fixed oil ; however, even with a strong heating, if the combination between the oil and resin is not perfect, the resin will eventually separate and precipitate out of the oil. Again, natural Balsams seem to offer a route around this quandary. But when a Balsam is heated, its essential oil is driven away, leaving the resin behind. Such remaining resin does not "like" to habitate with oil; it takes a very strong force (600+degrees F. heat) to fully combine them! This act will produce a resin-in-oil varnish. I suspect it is only then such oil-altered resins may be perfectly useful to oil painting.

But, realize, I am rather alone in my odd thoughts....

The common Amber varnish of the 1500-1600's appears to be a valuable, safe, and proper additive to oil paint and painting-technique. My light and clear 16th Century Amber Varnish and Venetian Amber Varnish should meet or surpass all pure amber varnishes in all regards. For handground paint the proper method would be to rub the pigment and oil up with the knife to a desired heavy or thin-cream consistency, then add, say, a drop or two of either the 16th Century or the venetian Amber Varnish (more will in no way help the effect). The amber will somewhat shorten the paint and keep it that way throughout the painting session. To apply impasto, simply use this amber-treated paint as is.

However, to paint in a 'Van Eyck' manner, thin the now amber-treated handground paint with some turps and mix with the knife to a soft facile condition ; use this soft paint to apply the layers atop your drawing without ever needing to oil-out. This paint in combination with a solvent creates enamel-like effects that are wonderfully bright and clean. [Again, handground paint is referred to here ; various modern-day commercial tube colors may not behave the same. This is due to the gelling agent given the paint so as to stabilize it for a long shelf-life.] If the painter desires extended open-time for paint manipulation, the 16th C. Amber varnish is recommended. If the Venetian Amber Varnish is utilized, the layers will dry faster, allowing overpainting on the morrow.

For those who prefer a non-solvent-requisite technique, add a droplet of varnish to your paint nuts at make-up ; then, make a medium composed of two parts un-refined Walnut oil per one part varnish, as was utilized successfully by, likely, both father and daughter Gentileschi. Use the medium to very thinly oil-out your ground or underlayers before each additional layering. Note: it is not necesary to bulk both the paint and your medium with amber varnish. In fact, too much Amber varnish in the paint will cause what the old painters called a "horned" surface that, when dry, is so unpleasant to overpainting and may even lead to future scaling. The constructed medium is a valuable tool. It should be used for oiling-out before additional layers or reworking. Of course, it should be very thinly applied ...just enough to lubricate and easily spread the new paint.

Below is a small 12x16 pleinaire made 07/08/02 with freshly rubbed-up paint using walnut oil and given a slight addition of Venetian Amber Varnish. This type amber varnish encourages faster drying whereas the 16th Century Amber Varnish has no effect on drying. I also carried along a bottle of "Gentileschi's Amber Medium", which was put into play for oiling-out the white ground before painting began.

This little view was commenced with a thin drawing and shading of lampblack mixed with Venetian Red--this to create a warmish tint; then opaque colors were applied in their respective places. The initial black/red mix can still be seen here and there in the shadow areas.

[note: I personally consider Walnut to be the best painting oil overall. When buying such, be sure the Walnut oil is NOT the refined and purified product increasingly available today-- if it does not smell like Walnuts or taste like Walnuts, it is likely purified and will not behave in the best manner. Also, if the oil looks to be very light in the bottle, it is almost certainly processed and its best qualities negated thereby. As for the cold-pressed variety, that's better than hot-pressed, but the very ideal sort is a walnut oil made from toasted nuts-- in fact, such treatment produces an oil that behaves like aged walnut oil, giving greater gloss, less shortness, requiring less oil to work-up with pigment into paint ; AND the paint dries much faster.]

Amber Varnish as a final coating

Since time immemorial, artists have coated their oil-painted works with oil varnishes. And well before oil paintings came into fashion, egg tempera paintings were commonly given coatings of oil varnishes, too. [In fact, it may be posited the good current condition of many early tempera paintings is owed in part to such a final coating.] Though spirit varnishes gained great popularity after the mid-1500's, still oil varnishes never disapeared from such use. Of course, this oil varnish-use is contrary to current thinking. Yet history shows the method can be quite sound. For ready reference, Holman Hunt and other PreRaphaelite painters (as well as many other 19th C. painters of merit), used amber and copal oil varnishes not only in their paint but also as final coatings applied atop the paint. As the Tate Gallery's collection shows, no harm has come from such practice.

For those who think oil varnishes are a dastardly mistake, I can only tell you Rubens informed DeMayerne that all spirit varnishes, in time, become arid (oxidized, powdery, etc.), and that the best final varnish would be made by mixing the common spirit or 'painters' varnish with a thickened and siccative (drying) oil -- this process effectively producing an oil varnish! I'll necessarily presume Mr. Rubens followed his own advice ....and who can fault the current excellent state of his works?

And do realize that, in perfect eventuality, all coatings dry and powder away, allowing rather easy removal by knowing conservationists ; and without harm to the better-preserved and actual underlying oil paint. In fact a good case could be made that the relatively fine preservation of many olden works has come about through final protective coatings which were tough and durable oil varnishes-- and not the supposed "soft" or "easily-removed" spirit varnishes so in vogue today.

Coating : I believe it is important to keep all final coatings as thin as possible. Boat-hulls are one thing and oil paintings are another. With paintings, intended for exhibit indoors, excelling protection does not come from slathering on the varnish. Instead, the coating should be thin ; in fact, I'd refer to it as 'super thin'. Make one droplet of oil varnish (or an amber oil medium) cover a wide area, say, about 5 inches square. Yes, it can be done. Use a half-inch hog bristle to scrub it on vigorously. Do a small section at a time. When finished with the whole, set the work in sunlight for a half-hour ; and then bring it back inside. The coating should be dry overnight. [Or, leave it in the sun, if not too hot, and the work shall be dry in two hours. But recall Vasari's story of Van Eyck, who, having placed his freshly-varnished work in the sun to dry, had the panel subsequently split-apart from the heat.]

Either of our amber varnishes, the 16th Century Amber Varnish, or the Venetian Amber Varnish, may be easily used for such coating purposes.[ The 16th C. is noticeably lighter ; and, as it is made using linseed oil, the Venetian Amber Varnish might develop somewhat of a gallery tone in time. As I generally thin either the 16th C. or the Venetian version with an equal amount of walnut oil, it shall make no never-mind. But other experienced artists use it full-strength ; even applying the varnish in the olden methodology, which was by rubbing it on well with the hand/ fingers ; sometimes in direct sunlight to warm the varnish, as it then glides upon the work with the greater ease. BTW, if a painting shows 'beading' occurring when applying the varnish, then stop and take it out-of-doors into sunlight for an hour. The sunlight will warm and drive away the 'fattiness' atop the dried paint-surface that is causing the repellency. Another safe indoor method is to rub the surface with a slice of potato or onion.

On the easel: the following exquisite sun-filled work showing Merlot grapes being gathered from the field is an oil-on-canvas by California artist Scott Methvin. Mr. Methvin relates that he uses the 16th Century Amber Varnish -- full strength-- to coat his completed works ; his method of application is generally both with the brush and the fingers, together.

Mr. Methvin applies his varnish thinly upon such canvas works. However, he also paints many works on copper, to which he applies a thicker coating. Of course, thicker coatings mean the natural yellow trait of the amber will be visually noticeable ; but Mr. Methvin plans for such by painting his work in more of a red-ish/blue-ish manner ; and he thus depends on the thicker amber coating to provide the extra tinge of yellow. The final effect is one of a captivating lucid depth.

Additional: Amber, What Is It?

Amber is the strongest natural resin known. It is derived indirectly from the balsamic-production of ancient coniferous trees, such as certain species of pines. Today, it is found in clay-layers buried for supposed millenia; and some geologists maintain Baltic Amber could be 20 million years old.

How was it formed? We are told that amber in a once liquid freshly-exuded balsam dripped downwards from the wounds in certain parent trees and encapsulated unlucky bugs that wandered into the sticky material. Somehow this sticky material hardened and got buried in the ground and, with time, formed a clear fossilized "bug nugget". This sounds perfectly and unwittingly sane and anyone seaching around a pine tree is likely to find example of this sticky exude trapping bugs. However, I cannot reason this to be the proper scenario.

As a landscape painter, I have observed nature and "played" with natural resins for most of my life. I must proclaim that, contrary to popularly-held belief, balsams do not simply "dry" ( i.e., lose their essential oils) and quietly form into clear and firm resin nodules, which, with burial and time, becomes that marvelous substance we call amber. Instead, balsams lose their essential oils and shrink, become porous, opaquely-colored, and gummy. Thus, nothing much becomes of them. In other words, if we were to continue to watch that unfortunate bug encapsulated within the gooey balsam, that balsam would not harden by itself and become a clear glassy material-- even if it were buried in the ground. You see, though it may eventually form a firm substance outside the tree through simple and normal exudation (drippage), this initially thin clear balsamic liquid does not remain clear for long. In no way does it go on to resemble solid and clear resins. That route comes instead from heating the balsam to make rosin. The simple heating of fresh balsams, or the older and opaque sticky gums, to drive off the containing, or remaining, essential oils DOES indeed result in clear amber-like resins (though such resins, often called rosin, without further treatment from other agents, are brittle and "splintery" none-the-less).

Thus, the very clear product today known as amber much more likely came about through the forceful heating of the original balsams and partially-dried opaque gums exuded within the ancient conifers. In other words, trees that exude or contain balsams within the trunk and bark, like Larch and Fir and Pines, are the prime candidates for producing future amber-like rosin formations. The heating of the gums and balsams took place as a result of some natural conflagration ( like a forest fire -- though it's also possible a strong tropical heat may do service) which produced heat enough to kill the ancient trees yet allowed their trunks to remain standing for many years before being weather- toppled, then errosionally buried by mud-slides. Of course, the likely location of trees for amber-production were those growing on hillsides, not flatlands, though volcanic activity could alter the scheme. Further, the flowing heated amber resin (rosin) had to be gravity-directed downwards within the tree, where it accumulated within eaten-out cavities. These available cavities, which allow perfect safe and dry burial of the quickly-cooling (thus, "freezing" in place) deposited resin, were created by now-extinct wood-boring insects. By necessity, these hollows would be located mostly within the lower trunk areas. Any bugs still residing within these cavities, though they were safe from the fire raging around the tree, would be trapped and quickly "frozen in time" by the flowing and accumulating hot rosin. As the heated rosin came from multi-numerous "pitch-pockets" or other balsam stores extant throughout the tree, a great voluminous mass of hot flowing rosin could be conceivably brought downwards to fill such voids, especially those within the lowest part of the trunk.

Compounding the means to amber-formation, I do agree Father Time is an essential influence upon the supreme hardening of rosin into an amber-like state, but it would probably not require millions of years to achieve a similar toughness. In consideration, I could believe such hardness might come about in hundreds-of-years instead. I feel this is more likely, as I believe either the heating or rotting of the tree allowed one further possible ingredient into the amber equation. This ingredient was a certain amount of natural vegetable oil available either within the wood of the parent tree, or it arrived by the included burial of newly propagated vegetation growing amongst the dead forest in the years following the conflagration-- an oil that compounded with the basic sleeping rosin and which caused the two to eventually form a very hard and durable union (you see, the rotting of the parent tree and other vegetation within the mud "tomb" would likely allow decomposing vegetation products--like oils-- to combine with the "sleeping" rosin. Though a lump of simple coniferous rosin seems to initially repell oil, be aware immersion or a lengthy familiarity will allow the rosin to slowly imbibe an amount of the natural oils). The final combination of organic oils with the basic coniferous rosin castings (positives from the bug-chewed "molds") created a product that was far stronger than either of the separate two. This oily ingredient allowed a plastic-like toughness and resulted in the peculiar ability of amber and other similar hardened resins to float in salty water-- something simple rosin cannot do.

And so, I surmise amber is the direct result of several conditions: natural physical forces (forest fire on hill-side location then later errosional burying and dormancy), the fauna (bugs eating out cavities for containment of the flowing hot rosin), and flora (the parent tree/other vegetation and an availability of balsamic gum and oils within the confines of the woody part of the tree. Any external gums and resulting heated resins would not survive the fire or future weathering. As such, drippings and exudations outside the tree were not the route to amber formation. BTW, I feel strongly that, under the same conditions today, modern conifers could easily produce actual ambers. In fact, I believe coniferous rosin allowed through heating or repose to imbibe a small percentage of drying oil-- like linseed or walnut oil-- might indeed become greatly toughened within many years of such treatment. Interestingly, I have heated 5% linseed oil into common rosin and obtained a product that floats in the same degree of salted water as amber. Yes, I believe it possible to artificially re-create amber. [ I realize science does not yet share my odd view regarding the formation of amber. Look up amber on the web; see what those of science say.]

Further in-depth report on my own experience with amber, click here.

James C. Groves June, 2001

Addendum: An interesting recent finding from the on-going MOLART study concerning oil-resin varnish. Though the info concerns copal oil varnish, the findings would doubtless also apply to amber oil varnish (note: I have underlined certain salient keys) :

[ Quote] "PROGRESS REPORT 1999 Many accounts in written sources point to the use of copal-oil media as varnish or paint medium. However, hardly any analytical evidence for the use of copal-oil media in paintings has been found to date. Studies on the ageing of copal-oil media were performed on varnish reconstructions of Leslie Carlyle with the aim to find any explanation and to develop analytical methods that could lead to the identification of copals in paintings.

GCMS studies showed that already in the process of manufacture the concentration of the diterpenes decrease relative to the oil components due to isomerisation, and probably polymerisation (Diels-Alder reactions etc.). This is explained by the extremely high temperatures that were applied (often >300 ºC) in the manufacturing process to melt the hard copal resin before adding the oil. In the drying and ageing process, the remaining characteristic diterpenes were found to disappear completely probably as a result of oxidative degradation and cross-linking. What remains is only the signature of a heat-bodied oil.

A possible solution to this problem could be to analyse the polymer fraction of the copals. Pyrolysis-GCMS was applied using a novel two-step technique designed for selective analysis of remnants of polymer structures. The procedure involves a two-step pyrolysis-GCMS technique with on-line hydrolysis and derivatisation with TMAH, evaporation and analysis of the low MW material in the first step. In a second [step] pyrolysis traces of polymer fractions in the residue are analysed specifically. With this technique, it was found that some characteristic marker compounds of the copal polymers could still be found. As a major breakthrough traces of copals could be identified in two paintings from the Pre-Raphaelite artist J.E. Millais ('Vale of Rest' and 'Mariana in the Moated Grange; Tate Gallery)." [end quote]

And so, based on what this 1999 Molart report has uncovered, much of what we have been told about resins not being found in old master works is fraught with uncertainty. It would appear that the many findings of heat-bodied oils in old master paintings (for instance, such as those detected in VanDyck's and Ruben's works, and Rembrandt's, too) may be instead the actual remains of resin oil varnishes, and not merely simple boiled oil alone . What is apparent, is that science's rare findings of historic resin-use with oil paint has most likely heretofore come from the beguiling analysis of spirit varnish-layers or paint additions, rather than resin-in-oil varnishes, whose remaining resin 'markers' are beyond our conservator's current state-of-the-art identification techniques.

James Groves, September, 2001- Updated July of 2002

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