Thanks again for your input Donna, it’s all very informative.
I posted this issue to this thread, and the conversation there focussed more on my questionable use of oil pastel, which they said never really solidifies/cures/dries, and therefore could melt in warm conditions, eg. under a hot light. However, the more I look at the brown, unpigmented appearance of the drips, and given the conversation in this thread, the more I think the problem is in the underlying layer of oil, as you suggest. In particular, if you look at the upper region of the painting, you can see that the surface has a wrinkled appearance. I believe in that period I was experimenting with not merely applying an intial oil layer with a brush, but pouring it in large quantities onto the canvas laid flat and then letting it dry. Thick blobs and puddles would form, which would sometimes crinkle up as they dried. I expect that you’re right: only the outer layer properly dried, leaving a wet pocket inside, and as the painting dried, the outer layer cracked and the liquid inside oozed out.
This is particularly troubling to me because this was not exactly a one-off experiment; virtually all the paintings I’ve done in the past 10 years were executed using a similar techniques. I’ve sold a number of them and am now quite concerned that other patrons may be experiencing similar issues. Fortunately, I rarely used the huge amounts of oil as I did in this piece, but usually instead applied it only in a thin layer, if at all. As I said in the beginning, I have many paintings from this era, and none of them have this problem. On the other hand, they have all been stored in a relatively dark (slotted together on a shelf), climate controlled space, which is why I wondered if being exposed to light or heat might be what caused the problem.
In any case, I’m definitely going to do more research into this before proceeding with my practice, and will contact the manufacturer of my oil pastels (Sennelier) to see what they have to say about combining their oil pastels with oil paint, and will also inquire about switching from oil pastels to oil sticks. I’ll also get in touch with some of my old patrons to see if they’ve noticed similar issues.
Thanks again everyone, and please continue to offer feedback and suggestions if you have them!
Hi Jeremy! First off, your work is beautiful! Someone recently explained the fat over lean principle in a way I could understand more easily as “slow drying over fast drying.” Different oil color pigments dry/cure at many different rates, and the idea is that you want to use fast drying pigments in your first layers and slower drying ones in the top layers. A list of popular oil colors and their drying rates are explained in the book “Traditional Oil Painting” by Virgil Elliott. This book helped me so much. Perhaps the reason why only one painting dripped out of many had to do with the choice of pigment combinations, where a very slow drying pigment (ex. alizarin, ultramarine, ivory black) was used first with a fast drying pigment on top (ex. Lead white, naples yellow, chromium oxide green, yellow ochre, raw umber) which would seal in the wet paint. Just speculating.
Oil color is generally applied to either an acrylic or oil ground. Not that you can really see it, but they have more “tooth” than priming a support with paint with have. Generally your paintings will last longer if you apply layer on top of layer of a more matte surface, much like when painting a wall or furniture. It is very hard for any type of paint to stick long term to something glossy. Think how easily dried paint scrapes off a glass palette vs that drip that hit the matte wall (sorry landlord!) When you place oil between your paint and canvas, you are also placing something with zero pigment volume on top of the toothy ground. It’s a dicey scenario because the pigment particles were designed to lock into those toothy crevices and form a mechanical grip onto it, like a rock climber locking their fingers into cracks in the side of a mountain. However, a solution might be for you to prime with the oil color Lead White, because I was told it is super slick and your paint wipes right off. Do not ever sand this paint when dry to avoid lead poisoning, and wear gloves as needed but it dries very fast and you will be able to work on top of it quickly. I may suggest adding something to slightly roughen the surface like using a bristle brush to apply it. Once dry it will still wipe off but will have tooth to adhere the upper layers so best of both worlds. It is also creates an extremely hard, virtually indestructible paint film that will age well.
Indirect painting - it seems like you enjoy painting using a subtractive method, being able to remove areas and rework them. Have you ever considered additive - painting in very light tones and allowing it to dry and keep building it up in layers? I took a class where we were showed how to make modelling form easier by painting in greys just the middle values until we were happy with placement, then adding more contrast and brighter colors. We were also taught how to add linseed oil to our dried oil painting with a makeup sponge (non-vitamin E kind) and it was revolutionary for me, much less struggle and a whole bunch of happy. Yes you have to cover all of the oil with paint “or else,” concept fully explained above but search “oil pigment volume” for details.
The last point I wanted to touch on was about the oil pastels. I’ve read they contain wax and so they never fully cure, however modern paint manufacturers currently add wax, fillers and other stabilizers to our paint that we use everyday and they still dry. Gamblin even makes a cold wax medium, which I’ve researched and used. In their literature they warn that if too much wax is used your painting could melt under high heat. So maybe if you use the oil pastels for sketching, make sure to use oil paints with the least amount of wax as possible, which would point me to Rublev oil colors by Natural Pigments. Their paint contains zero waxes or fillers. I’m slowly becoming a convert, their paint is amazing.