Hello dear experts,
I have a few questions about issues with various media when doing a thin underpainting layer for subsequent oil paint layers. I work on canvas board or wood, primed with acrylic ground.
1) I used thin watercolor-like washes of acrylics for a few pieces. Now I learned recently that the acrylics, even though they dry quickly, should be given at least three days before you paint over them with oils. I have not done that with the mentioned pieces, I went straight in with the oil paint once the acrylic paint was dry to the touch. So far (~2 years) I have not seen any issues with the paintings. Does that mean it is safe to work that way, or could strongly thinning the acrylics and/or not letting them dry for the recommended time cause issues down the road?
2) I have also experimented with water-miscible oil paint, and used it in the same way described above with the acrylics, thinned to a watercolor-like wash and painted over with oils once dry to the touch. Again, those pieces are fine after about the same ~2 years. I learned in the meantime that one shouldn’t thin down oil paints to that degree, as that might cause an underbound paint film. My question here is, though the pieces are fine now, might issues arise down the road due to the underbound layer?
3) If I use watercolor as an underpainting, a few washes, how long would they need to dry before applying oil paint? And do I need to seal them somehow before that, or can I put the oils straight on top of the watercolor?
My basic concern is the longevity of the pieces. I don’t care about them lasting for centuries, I just need them to be good for a few decades, so my clients can enjoy them in their lifetime. When doing underpaintings the way I described above, is it at all possible to estimate what kinds of issues might arise with the pieces, and how soon?
I apologize if any of this has been covered in the forums before, and I overlooked it. Thanks in advance for any help with these questions!
Hello Brian,
thanks for the quick reply. No worries, I appreciate your input!
Aside from problems that might arise during cleaning, let’s say the paintings develop issues, what problems can theoretically be caused by a not thoroughly dried acrylic bottom layer, or an underbound bottom layer? Until doing some research in this forum I had been of the naive opinion that if very thin, underbound layers are not left uncovered, but “sealed” by subsequent layers, they won’t be an issue. Now I got the impression it’s more complicated than that and covering them isn’t a guarantee, but I still don’t fully understand all the issues that can be caused by underbound layers. Do they threaten the adhesion of subsequent layers, or is it an issue with unbound pigment rising to the surface?
Also, do you have a comment on using watercolor under oils? In my research I found that sometimes, but not always, it was suggested they be sealed before putting oils on top, and when it was suggested there was never a reason given for why that is necessary.
Thank you!
It is really difficult to say whether a work will develop adhesion problem “down the road” if they seem to be doing fine after 2 years. Probably if they are kept in a mild, stable environment they should remain in a similar condition. There are, however, too many variables to make definitive predictions about this. Likely, you will be fine. The real test would be if the works need to be cleaned in the future.
Sorry, I could not be more precise in my answer.
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