The 3 art materials oil painters should avoid (in certain circumstances) include Zinc Oxide, Clove Oil, and Solvents. All 3 are usable under the right conditions, so I will explain a bit further to eliminate confusion.
I’ve decided to modify my thoughts about Zinc Oxide in relation to oil paint. George Hanlon of Natural Pigments cites the Meclenberg studies at the Smithsonian to caution against using zinc in oil painting. The studies show that zinc cause oil paint to become brittle (prone to cracking) and can cause the paint to delaminate (peel off). There is a ton of research available about the downsides to zinc oxide, but one of the best articles I’ve read is found on JustPaint.org.
A nagging doubt has pestered me since I learned about the zinc debate. How many paintings have actually cracked and delaminated that were painted with zinc on an oil or lead ground. Try as I might I have not found a list of paintings that have suffered any more than the traditional cracking that comes with ageing oil paint. We have about 200 years worth of painting with zinc oxide and yet the evidence is either suppressed, ignored, non-existent or not divulged to the public (or I just haven’t done enough research).
Knowing that Dan Gerhartz and Richard Schmid have used Lefranc White (which contains zinc) as their primary white for at least 4 decades, I would think we would hear about the severe cracking problems they’ve dealt with. I’m aware of one painting Schmid had to repair a few years after painting it – but it was caused by using too much of the old fugitive Alizarin Crimson, not from using white.
Then I saw an article that ascribed the cracking of zinc white to oil paint on acrylic grounds. That made sense to me since the oil paint does not adhere as well on acrylic as it does on oil or lead grounds. As far as I can tell, it appears all of the studies were done using zinc on acrylic grounds.
My new recommendation, if you use zinc in your ground or in your paint, is to use oil paint only on a lead or oil primed surface and not on an acrylic gessoed canvas or panel.
A zinc/titanium white mix is popular among landscape painters because zinc white remains brighter over time than Titanium alone and forms a stronger paint film in the long run than Titanium.
Clove oil is fantastic for slowing down the oxidation (drying) of oil paints. I’ve been experimenting with clove oil and a palette cover to slow down the drying of the paints on my palette.
Avoid mixing the clove oil directly into your paint. Clove oil softens the final paint film and leaves it susceptible to damage – just ask conservators who’ve worked with paintings where clove oil was mixed into the paint. The softer ‘skin’ allows dirt and pollutants to embed more easily into the paint and the gentlest cleaning agents can damage the paintings.
That’s what happens with water-mixable oils as well. The paint dries slower and softer than traditional oil paint.
Artists have experimented with lots of solvents. Solvents evaporate and leave little behind. Oils on the other hand oxidize and form a tough shell to protect and bind the pigment (color) to the painting surface.
Artists use solvents such as Turpentine, Mineral Spirits, and Spike Oil to add fluidity to their paints or to create watercolor type washes that they can easily cover their canvases with. The solvent evaporates (dries) quickly (within minutes) and can then be painted over without fear of substantially altering the initial wash.
The main problem with solvents is that the evaporative nature and the aromatics are generally toxic and over time can cause severe health problems for artists. Turpentine is one of the worst. The toxicity of Spike oil (lavender) is mostly unknown – no real studies have been conducted. My own experience is that it caused me to feel flushed. Because of that, I stopped using it. It smells great (if you’re a fan of lavender), but the smell is powerful.
Mineral spirits (especially Gamsol) are the least toxic since they’ve removed 99% of the aromatics. Even so, it’s still toxic. I used it for almost 30 years without noticeable negative effects which seems to be the case with many artists, but other artists have developed strong allergic reactions over time. I decided to stop using it about 10 years ago just to avoid potential problems.
The other downside is that we artists think we can mix a watery soup, and everything will be grand. All solvents, including mineral spirits, weaken the paint film – they thin the binder (oil). Too much solvent will effectively remove the binder and leave the pigment to flake off the painting. So, if you use solvent, use it sparingly.
What art materials do you avoid?
Stay Healthy and Happy painting!
is retouch varnish safe to use? some people endorse it, others not.
Im not an expert on any of the chemicals that clutter my studio but I have used retouch varnish for many years. It really smells awful so Im always outside when I use it. I let it dry before bringing it back into the studio.
That’s a great question, Linda! In the past, I used Retouch varnish and would have said yes, but based on newer research I stopped using it. First, as James mentioned, the fumes are usually toxic. Second, conservators say the retouch varnish creates an unstable film between paint layers, especially if you ever try to remove a final varnish to clean a painting. The retouch varnish does not form a strong, flexible film like the oil in the paints and is easily damaged by solvents that do not affect the actual paint film.
So, what have you used for the last ten years?
Great question John! I’ve replaced Gamsol mostly with a little walnut oil or Rublev Walnut Oil Gel. Recently I began experimenting with watercolor when I want to play with underpainting washes. With watercolor, I can paint almost immediately over the top with oil paints. Then, once it’s all dry, I varnish over the whole painting with Gamvar which protects both the oil and watercolor paints.
What is the best product for cleaning brushes used for oil painting?
Check out this blog: https://www.masteroilpainting.com/clean-oil-paint-brushes-with-turpenoid-natural/
I did some checking about using watercolor for underpainting as I was interested in using it. It was not recommended as it contains gum Arabic or other preservers.
What is the difference between walnut oil medium and walnut oil alkyd and when would you use each?
The alkyd version dries faster than regular walnut oil. I haven’t used the alkyd so can’t comment on when to use it instead of walnut oil but presumably if you want faster drying time.
Typing error should read “dries faster”
I use Vaseline to clean my oil painting brushes on the advice of a well known oil painter.
Vaseline is not a drying oil like Linseed or Walnut oil. If you use it because it is convenient and works well for you, I would recommend you clean your brushes thoroughly with soap and water. Vaseline is a petroleum product and not compatible with oil paints as far as the actual painting process is concerned. An excellent product I’ve been using for 30 years is Turpenoid Natural. I describe how I use it to clean my brushes in a blog post here: https://www.masteroilpainting.com/clean-oil-paint-brushes-with-turpenoid-natural/ – when the paint is extra dried on the brushes I soak the brush in the Turpenoid Natural for a couple of hours. To clean my brushes I dip the brush in the solvent and then work the paint out on my palette. Once it’s clean I use a paper towel to squeeze out as much Turpenoid Natural as possible and then the brush is ready to use. The tiny amount left in the brush will not damage or cause problems with the paint drying.