MITRA Forum Question Details

I've seen something matching this description before, involving layering with oil paint and alkyd medium. In my case, a fresh application of oil paint with alkyd medium was applied over a completely dry layer of oil paint without alkyd. As you describe, the new layer was easily scratched off at first, but later, when the paint became stiffer and not so "fleshy", it was not as vulnerable.

I wonder if it might be advisable to abrade or lightly grain the first layer when layering in this combination. ​I recall Taubes used to recommend something like this, but his advice was based on independent studio work and not scientific experiment.

It seems to me that paint that can be easily scratched or removed from a ground is a bad sign for future longevity although it is possible that with time the paint will dry and be more resilient. I would guess that the paint you used for your ground was either not absorbent enough or crated a closed film with no mechanical tooth. Conversely, perhaps the scrubbed on oil layer was too lean.

There is nothing inherently wrong with a good quality alkyd binder. This has been show by decades of use and testing by coatings manufactures. I have generally found alkyd artists paints to be looser with less pigmentation than high quality artists’ oils (this is a very complicated subject on its own as “stabilizers” and thickeners can be added to an oil, or alkyd, to make them very stiff and appear to be super loaded with pigment).  On the other hand, those alkyd artist paints that I have observed created far more transparent and glossier films when compared to an unmodified oil paint film of the same pigment. I have not experimented with Gamblin’s alkyd paint line, which I understand was formulated to be quite lean and a good choice for underpainting. So again, I doubt that the problem is the result of a bad material. Alkyds are perfectly acceptable and useful in the right situations.

Galkyd may or may not be appropriate for a specific paint effect, but it is a reliable medium for use with oil paint. Artists, like the public at large often have strongly held opinions on subjects that are based on faulty assumptions, misinformation, and biases. Some these become are repeated so often that they take on the air of concrete truth. An example is the often repeated idea that graphite somehow migrates through paint films. This is not and never has been true but it still comes up on forums, including this one.  One of the goals of MITRA is to dispel some of these myths.

Back to the alkyd containing paint. Zinc is problematic in large percentages in the long term (search the forum for a discussion about zinc white) but its presence would not contribute to the defect you mention.  

More to the point, I will send a message to M. Graham to see if they would like to comment on this thread. I will also send a message to Gamblin to see if they would like to comment on Galkys and alkyd paints.

I agree that the alkyd white used on this canvas was too binder-rich to be used as a ground. A light sanding with rough sandpaper, followed by wiping of the dust, will open up this layer and make it more receptive to subsequent paint layers. In the future, consider using a true alkyd/oil Ground or an alkyd white made for underpainting (Gamblin makes both of these – our Oil Painting Ground and FastMatte Titanium White. Both of these products, when applied thinly have an adequate tooth to provide mechanical adhesion to subsequent paint layers).

In regards to Galkyd, being a high viscosity painting medium, it levels brushstrokes and increases gloss. If too much is added to oil colors, early on in the painting structure, the leveled/glossy characteristics of the resulting paint layer may make for a closed/slick surface for subsequent layers to adhere to. Consider this medium “fat” in the Fat Over Lean guidelines – use sparingly in early stages and more as you build up the painting so the structure moves in a “matte to glossy” direction, which will help with adhesion. If you need to paint on a glossy layer, consider a light sanding/steel wool treatment first. For more information on FOL, please refer to our website. It’s also worth mentioning, we also make Galkyd Lite and Galkyd Slow Dry – both speed drying of oil colors, but are leaner than our straight Galkyd.   

In addition to the FOL info (linked above), please refer to our page on Solvent-Free Painting. As Solvent-Free mediums, by nature, are all 100% fat, they should be used in moderation.