A Few Thoughts on Issues with Gamvar

In recent months, I have seen quite a few colleagues complaining about the popular varnish from Gamblin, “Gamvar.” The varnish has been a popular favorite among artists for many years—so I was surprised to see the recent spike in issues being shared across social media.

Issues range from the varnish remaining wet or “tacky” after long periods of time (weeks to months(+)) to significantly uneven finishes (varied sheen.) Gamblin (and the distributors that sell to the public) describe the varnish as follows: Developed in collaboration with the National Gallery of Art, Gamblin Gamvar Gloss Varnish saturates and gives greater depth to the colors in your painting and gives your work a unified and protective semi-gloss surface. Virtually odorless, premixed, and ready to apply, Gamvar Gloss goes on water-clear, stays water-clear, and can be easily and safely removed with Gamblin Gamsol Odorless Mineral Spirits. Gamvar Gloss can be applied with a brush when the thickest areas of your painting are thoroughly dry and firm to the touch. Spray application is not recommended. The 4.2 oz size covers approximately 80 square feet (7.5 square meters). The 8.5 oz size covers approximately 160 square feet (15 square meters). The 16.9 oz size covers approximately 320 square feet (30 square meters). To achieve different finishes, you can also use Gamvar in Matte or Satin. Gamvar Matte reduces surface sheen while maintaining the deepest values in your painting. Gamvar Satin saturates the colors in your work but dries to a lower gloss level compared to original Gamvar Gloss. Note — Original formula Gamvar Varnish is now called Gamvar Gloss. The formula hasn’t changed, just the name. (Dick Blick)

Now while the last line of this description promotes the idea that Gamblin has preserved their original formula–one artist, Richard Murdock, claims that both Robert Gamblin and Gamblin Product Manager Scott Gellatly, have admitted otherwise in conversation. It is in fact this alleged change in formula that Mr. Murdock blames for the recent host of issues being reported.

Natural Pigments founder George O’Hanlon stated that the original he original recipe for Gamvar produces a 13% weight of Regalrez 1094 to volume of solvent. Regalrez 1094 is a synthetic hydrocarbon resin that does not crosslink upon aging, so it is easily removable with the same solvents, such as odorless mineral spirits, that dissolve it when newly applied. Regalrez is a good choice as a final picture varnish because even after aging it can be removed with non-polar aliphatic solvents, such as odorless mineral spirits.

Speaking of cross-linking–one NY conservator that recently weighed in on a problematic application of Gamvar attributed the cause to “cross-linking.” For those unfamiliar with the term, drying oils can polymerize (a polymer is a substance that has a molecular structure consisting chiefly or entirely of a large number of similar units bonded together). A molecule that can polymerize is a molecule that can form a chain. As the molecules polymerize and join up into long rope-like polymers, the oil becomes thicker. (Bigger molecules like polymers are harder to move around.) A cross-linked polymer network is like a mesh of chains all woven together. A single cross-link between two polymer chains connects them and makes them act like one super-sized molecule twice the size of each original polymer. Cross-linking multiplies the size of the polymer molecules. Sometimes there are enough links to connect all of the polymer molecules into a single mesh. When this level of cross-linking happens, there is no longer a way to dissolve the polymer molecules - they all go into the solvent together in one lump or they don’t go at all. As such, you can say that the oxidation process for oil paint has two major stages: 1. Polymerization of the drying oil into long polymer chains. 2. The cross-linking of the polymer chains. So how can cross-linking lead to a varnish that won’t dry? …I have no idea. It is true that cross-linking is often undesirable where a varnish is concerned. As I stated, cross-linking can absolutely lead to insolubility–a state that would not be conducive to future restoration techniques.

(Here’s a but more insight on the Regalrez resin found in GamVar from Jill Whitten, a Mellon Fellow at The Chicago Art Institute. Text provided by artist Richard Murdock.):

Regalrez 1094 has been used with success for the past three years at The Art Institute of Chicago in instances where saturation is needed for canvas and panel paintings, as a means to resaturate synthetics and natural resins that have become dull, and in dilute concentrations in instances where it is appropriate to even areas of matte and gloss. The most common uses have been to resaturate PVA and Lucite varnishes applied in the 1960’s and to resaturate natural resins that had become dull, on paintings that were not slated to be fully retreated . Vastly improved surfaces were achieved with spray or brush applications of mixtures of 25-30 g of resin in 100ml of solvent. The resin has also been successfully applied to panel paintings over synthetics or as the primary varnish in amounts ranging from 10-15 g per 100ml of solvent. You can also apply a thin coat of varnish using a cotton ball wrapped in silk. These new LMW resins also have the advantage of dissolving in far less polar solvents than are necessary for natural, ketone, and methacrylate resins. Therefore, they can be applied locally in instances where a tiny bit of saturation or evening of matte and gloss is required. Examples might include 20th century, naive or folk paintings that might be sensitive to most other solvents and that should not have the appearance of a distinct varnish layer. Questions remain about spraying and building up subsequent layers with Regalrez and about achieving matte surfaces. Mark Leonard has suggested that spraying higher concentrations of 35 or 40% may yield matte surfaces. According to product literature, Regalrez 1094 exhibits excellent compatibility with paraffin and micro-crystalline waxes.

The type of substrate you wish to varnish will help determine which concentration to select. Regalrez 1094 looks much more like a natural resin when it is applied to a weathered or aged surface than it does on a newer, rich oil film. This varnish can be used successfully without the rubber additive but it is highly recommended that you add Tinuvin 292. It is also important to discard varnish mixtures after three weeks because Tinuvin 292, and resins in general, degrade faster in solution than they do in a dried film. I make small batches for this reason. In some cases the ready solubility of Regalrez 1094 can be a drawback. Built-up spray layers can reticulate and it can be tricky to inpaint on. For paintings that require a great deal of in painting you may want to use an isolating layer of stabilized dammar or B-72, with a final brush or spray application of Regalrez 1094."- Jill Whitten, a Mellon Fellow at The Chicago Art Institute.

While no one has yet pinned down a good reason for the Gamvar (beyond Richard Murdock’s claims of reformulation)—some like George O’Hanlon, artist Virgil Elliot and Gamblin Product Manager Scott Gellatly have stated on social media that the disparities in finish are due to a form of sinking. George O’Hanlon stated “The issue here is sinking in. Low molecular weight (LMW) resins in varnishes such as Gamvar are prone to sinking in due to paint with matte surfaces. To prevent this use a polydisperse resin or a high molecular weight resin”. In a similar fashion, Scott Gellatly recommended spot-varnishing low gloss areas to match higher gloss ones. He writes, “Try spot varnishing this area only to bring it to the gloss level of the surrounding area. This area was likely more absorbent than the rest of the painting and the varnish sunk in. In the future, consider “oiling out” the painting prior to varnishing. This unifies the absorbency rates and makes for a more even (and predictable) varnish application. Please see our video demonstration on the Gamblin website:https://www.gamblincolors.com/video-demonstrations/ (It should be noted that some (like George O’Hanlon) recommend avoiding a final oil out if possible as “even a small amount of oil applied to the surface will yellow and cause darkening over time…the best practice is to avoid oiling out altogether.”

Unfortunately, many of the issues that people are experiencing with Gamvar end up requiring removal of the varnish (often with GamSol OMS) and a varnish reapplication.

One popular alternative to Gamsol that has been recommended by many of my colleagues is Conservar by Natural Pigments. The varnish is described as follows: “Conservar Finishing Varnish (made by Natural Pigments) is a colorless, reversible varnish made from hydrogenated hydrocarbon (Regalrez 1094) resin dissolved in pure, low-aromatic solvent and UV light stabilizer. Conservar Finishing Varnish is made according to the original formula developed by E. René de la Rie formerly of the National Gallery, Washington, D.C. Varnishes based on this formula will not crosslink or yellow over 100 years as shown by tests conducted at the National Gallery, Washington, D.C. Conservar achieves optimum wetting of the paint surface to enhance and bring out colors, has minimum solvent action on paint, and maximum resin content for best coverage. It dries to a film that levels well and can be rubbed when dry just like mastic or dammar varnishes.”-Natural Pigments

12/29/19 Update from artist Richard Murdock:

Reasons to not use Gamvar and recipes for making your own regalrez-based varnish:

Reasons (I wrote this a few years ago. Ingredients, etc. may be different now): I’ve used Gamvar for 10 years, and for the first seven years it worked perfectly.It could be applied as soon as the paint was touch dry, dried quickly, could be removed easily and is recommended by The National Gallery.

But 3-4 years ago something changed. The varnish suddenly was thinner, almost watery, and glossier in an unattractive way. I didn’t pay much attention until I started getting calls from galleries to come and re-varnish paintings, probably about 24 paintings altogether. I assumed that this problem was related to my working methods, but they hadn’t changed at all, and since I am methodical in execution it would make sense that I would have been having problems early in my career — not seven years in when I’ve worked the bugs out.

It wasn’t until a good friend began having the exact same varnish problems that I began looking into other causes for the varnish failing besides operator error. My friend uses different substrates, medium and varnish, Beva Finishing Varnish, although it is supposedly made from the same formulation as the Gamvar. A couple of dealers confirmed some of their artists were having varnishing problems also.

The problems are varied and unpredictable. They include sunken areas within the same pigment areas, odd cloudiness in random shapes, and very uneven appearance in terms of glossiness. The others I’ve spoken to have experienced the same problems, when there are problems.

After we went through all possible causes we were left with a mystery.

Until, that is, someone emailed me with a story about Bob Gamblin being forced to change his formulation about four years ago. A few days later, another friend confirmed hearing the same story, but without the formulation change. She also told me that The National Gallery had not been notified of any change in formulation, a major oversight on Gamblin’s part if the formula was changed.

Today, another friend told me she had dug into the Gamvar MSDS (Material Safety Data Sheets) and found some inconsistencies. The MSDS presented on the Gamblin site, under the Gamvar section, is dated 8/22/1995, even though there is a more recent one, dated 3/1/2011. The later MSDS is under the “Drying Oils” section, not where anyone would expect to find it.

Comparing the MSDS sheets to the Regalrez MSDS yields some interesting information. According to my friend’s research (waiting for confirmation) the Gamvar 1995 MSDS matches the CAS# for Regalrez (CAS#: 68441-37-2). But the Gamvar 2011 MSDS has a different number: CAS #28931-47-7 and it is identified as a Formaldehyde-isobutylaldehyde-urea polymer, instead of a hydrocarbon resin.


Patty Stiles, a member of the original RP forum (http://rationalpainting.org/) did all of the following work and research:

RE: Pulling It All Together: Make Your Own Varnish
I found some new information that should simplify this.

First, the scale in the earlier post above is the wrong one since it has a resolution to 2 decimals places, but does look like the correct one that has a 3 decimal resolution. Try this scale instead: http://www.oldwillknottscales.com/my-wei…e-101.html . It is accurate to 0.005 grams.

The Conservation Wiki has recipe information about Regalrez 1094 that give grams of resin per 100 ml of solvent for typical brush solutions.

• Brush varnish concentrations can vary from 10–40 g/100 ml of solvent depending on the substrate and the effect you are trying to achieve.
• If used alone, 20–25 g/100 ml is usually appropriate.
• If the surface to be varnished is uneven (areas of matte and gloss), begin with a higher concentration of 30–40 g/100 ml.
• A somewhat faster evaporating solvent like Shell Solvent® 340 HT works well for more general applications. Solvents or solvent blends in this evaporation range give sufficient brushing time and yet will evaporate fast enough that the varnish will begin to dry as you work and give a feeling of resistance to the brush.
• Shell Solvent 340 HT is now called ShellSol D38. Another good solvent is ShellSol D40.

To simplify the formula, leave out the Kraton G. You can always add it later after you have some experience with the basic formula.

The Tinuvin 292 comes in a dropper bottle. If you use 35 g of regalrez to 100 ml of solvent, you would add 0.7 g of Tinuvin (2% of the weight of the resin).

The author of the following website http://harrysteen.com/varnish.htm has experience making his own varnish and had some helpful hints.

• One drop of Tinuvin is about 0.03 grams. You can check that out with your scale.
• One blob of Kraton G is about .02 grams. You could also weigh a blob on the scale.
• The density of paint thinner is about 0 .77 grams per milliliter. You can weigh your solvent in the milliliter cylinder to verify that.
• The final volume of the varnish will not be much greater than the volume of the solvent.

Here are a couple of alternative Regalrez recipes Ben Sones found in the book “Conservation of Easel Paintings” by Joyce Hill Stoner.

• 20 grams of Regalrez 1094 in 100 milliliters of solvent with 0.4 g of Tinuvin 292 (2% of the weight of the resin).
• 20 grams Regalrez 1094 in 100 milliliters of solvent with 2 grams of Cosmoloid H 80 wax (10% of the weight of the resin).
• 20 grams of Regalrez 1094 in 100 milliliters of Shellsol TD solvent with 0.4 grams of Tinuvin 292 for large paintings or a great deal of working time.

The following vendors sell the materials you will need:

Conservation Support Systems Supplier
Sells Shellsol D40 solvent
Regalrez 1094
Tinuvin 292
Kraton G 1657 (extruded translucent pellets)

Talas Supplier for Conservation Products
Sells Regalrez 1094
Kraton G 1657

Kremer Pigments
Sells Shellsol D40 solvent CAS 64742-88-7 Aliphatic
Sells Tinuvin 292
Sells powdered Regalrez 1094

Museum Services Corporation
Tinuvin 292
Regalrez 1094
Kraton G1650 [fluffy, opaque white powdery pellets (replaced G1657)]
Kraton G1657 (extruded, transparent pellets)I’ve used Gamvar for 10 years, and for the first seven years it worked perfectly.It could be applied as soon as the paint was touch dry, dried quickly, could be removed easily and is recommended by The National Gallery.


One other item to mention: Gamblin says that they haven’t changed the formulation of Gamvar, but one very big change they did make was that they started offering it in pre-mixed bottles rather than in a “mix it yourself” kit form. Artists love this because it’s easier, but in reality, there’s a good reason why Gamblin originally only sold this varnish in kit form, and why you should never use premixed Regalrez varnish purchased from a store–not from Gamblin or anyone else. Rene de la Rie originally developed Regalrez varnish for use in painting conservation, and his research indicates that Regalrez forms a stable varnish only with the addition on Tinuvin 292. Without Tinuvin, it forms a varnish layer that is extremely unstable, and prone to rapid degradation.

Here’s the problem: Tinuvin 292 is good for years in its dry form, but it has a short shelf life once mixed into a varnish solution: about four weeks, max. De la Rei recommends mixing varnish fresh just prior to application, and not keeping mixed varnish for more than a couple of weeks.

So that bottle of Gamvar sitting on the shelf at the art store: do you think it was produced within the last couple of weeks? Or has it been sitting in the art store for six months, and maybe in a warehouse for a few months prior to that? If so, then you are effectively using unstabilized Regalrez, and all bets are off regarding how well it’s going to hold up.

My advice: buy your varnish in kit form, and mix it fresh just prior to use. There are still plenty of sources for varnish kits, or raw materials needed to make varnish.


You da man Ben! Thank you!