MITRA Forum Question Details

​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!