Once in a great while I come across a product that makes life in the studio so much easier that I feel compelled to share it with readers. I am not an employee of Gamblin, nor do I receive any compensation for this review.
Once a painting is done, the oil painter faces two vexing questions: should I varnish the painting and, if so, how should I varnish it? The “why” of varnishing is not the subject of this article, but for those who are interested, please see Why Varnish at the end. The “how” of varnishing, though, is more problematic. There are many different types of varnishes and brands and applying any of them incorrectly can easily ruin a painting.
1. It can be applied much sooner than traditional varnishes
An oil painting goes through a curing process that continues long after it feels dry to the touch. So as not to interfere with this drying process, it is usually recommended that you wait six months (for thin paint) to a year (for thicker paint) before varnishing. This is a real problem for painters who must release their work to buyers or galleries sooner than that. The Gamvar formula is permeable enough to allow the underlying oil paint to proceed with its natural curing process, so you can apply the varnish once the paint is dry. What’s more, the solvent component of Gamvar is mild enough so it won’t dissolve the thin glaze layers of the painting. Gamblin notes, “How do you tell if a painting is ready to varnish? It’s easy — just touch it. If there are impasto areas, gently press your fingernail into that impasto. If it is firm underneath the surface of the painting then it is ready for varnishing [with Gamvar].”
2. It is easy to apply
Gamvar is very thin and non-oily, so it can easily be applied in an even, thin coat. This is good news. Some brush-on varnishes are oilier and slightly viscous, making it harder to achieve an even coat. Spray varnishes can be very effective, but they require protective masks and a dedicated spray area.
3. It permits control of the surface sheen from glossy to matte
One of the benefits of varnishing is that it enables painters to adjust the surface sheen of the painting after it is done. It can also correct or even out shiny or flat (matt) spots. Like damar varnish, Gamvar has a high shine, which many painters prefer. It tends to saturate the colors, especially the darks, which may “sink” or lighten as the paint layers dry over time. Other painters, like myself, who prefer a matt or satin finish, can add cold wax medium to the Gamvar to reduce the sheen. To get the desired sheen, you will need to mix the right proportion of Gamvar to wax. See photographs and instructions below.
Gamvar also offers another advantage. It can be removed with Gamsol, a very mild solvent. Damar varnish can only be removed with a strong solvent such as turpentine. Being able to remove a varnish with a mild solvent means less risk of damaging the delicate paint layers.
Although Gamvar is easy to use, you should test it on an old painting first, as you would any new studio method. Gamvar naturally creates a gloss sheen. If you want a satin or matte finish, you will need add cold wax medium.
Shelf life: I am often asked how long Gamvar lasts. Scott Gellatly, product development manager at Gamblin, writes: “Gamvar does not have a specific shelf life, compared to other varnishes. As the case with all varnishes, however, they are best used as fresh as possible. Painters should buy the size container that is appropriate for their needs. Here is the approximate coverage for each size we now make available:
2 fl oz: 40 square feet
8 fl oz: 160 square feet
16 fl oz: 320 square feet
Avoiding streaks: If you are getting streaks you are probably applying too much varnish. Always apply varnish as thinly as possible, avoiding visible brush strokes. Those new to varnishing overestimate the amount of varnish necessary and apply far too much. Imagine that you are trying spread the varnish as far as it can go.
When a painting’s surface is more textured, say, from the weave of the canvas or the texture of the strokes themselves, streaking will be less noticeable. However, the potential for streaks is greater when the surface is very smooth to begin with, and the paint is applied very thinly with little or no visible texture. Then there is no texture to interrupt or camouflage the streaks.
Immediately after applying a very thin layer of varnish, I use a very soft, delicate, “fluffy” brush and lightly dab the surface. This breaks up the streaks. Use a quick, but light up and down dabbing motion, and pay close attention that you don’t miss any spots. The brush shown here (right) is a 2-1/2 inch wide Asian-style Hake wash brush with sheep hair. Note: It is preferable to not use the same brush for this dabbing step as you did for the varnishing. The varnishing brush is laden with wet varnish; its hairs will be clumped together and have less “fluffiness.” Use a dry brush with hairs that are still fluffy and open. If you must use the same brush as you used for varnishing, wipe it back and forth on a roll of paper towels until most of the remaining varnish has been soaked up. The hairs should regain some of their fluffiness.
Achieving a Matt Finish with Gamvar
The cold wax medium needs to be thoroughly dissolved into the Gamvar. This is very hard to do just by mixing the cold wax and Gamvar together in a jar and shaking vigorously. It’s very hard to get the wax to disperse. Instead, I recommend just mixing up the amount of matt varnish you will need for that session. In the above photo (left), you can see that mixing the Gamvar and wax together doesn’t initially disperse the wax very well. It will take mechanical kneading action of the palette knife to mix the Gamvar and wax into a unified, creamy mixture (right). Continue to mash and knead out any little chunks of the wax until the mixture is uniform and consistent.
What is the correct proportion of wax to Gamvar for a matt finish? I have found that 4 parts Gamvar to 1 or 1-1/2 parts wax makes for a good matt varnish. If you want a satin finish, then use about half as much was. That formula would be 1/2 part wax to 4 parts Gamvar.) But test your mixture first! Remember, you never want the mixture to get very thick, otherwise it won’t be easy to brush on and lay down a very thin coat. Every varnish looks shiny when wet; you will need to let the Gamvar dry overnight before you can evaluate the final sheen.
Tip 1: Mix the Gamvar and wax in a colored plate. This makes it much easier to see your progress as you knead the wax and get it to disperse.
Tip 2: Always apply varnish as thinly as possible, avoiding visible brush strokes. Those new to varnishing overestimate the amount of varnish necessary and apply far too much. Imagine that you are trying spread the varnish as far as it can go.
Tip 3: Immediately after varnishing, spend a few minutes inspecting the surface for any errant brush hairs or foreign particles. Then, lay a large cardboard cover or lid over the painting so as to avoid dust collecting in the varnish as it dries.
From the Gamblin website: Gamvar is a low molecular weight synthetic-resin gloss varnish developed by conservation scientists at the National Gallery. Gamvar can also be used for retouch. With a high refractive index similar to that of natural resins, colors are fully saturated to bring out the best in the painting. Unlike varnishes made from natural resins like damar and mastic, Gamvar does not yellow with age or become more difficult to remove. It contains a UV stabilizer and offers some measure of protection to less lightfast pigments, depending on how thickly it is applied.
Why varnish? Painters varnish their work for two reasons. First, it is a way to control the surface sheen of the painting once it is finished (as noted above). Second, a varnish serves as a protective coating. A painting, like the walls in your house, becomes dirty over time. Or worse, if there is smoke damage or the painting were accidentally splattered with a foreign substance, the varnish is what would be affected, not the paint itself. If you try to remove a foreign substance from an unvarnished painting, you risk damaging the paint surface. But when you remove a foreign substance from a varnished painting, you are only removing the varnish, and are able to preserve the integrity of the paint surface. Then, a new varnish can be applied. Needless to say, varnishing won’t protect the painting from mechanical damage. If your cat uses it as a scratching post (this really happened to me), varnish will not help!