Restoring "tooth"?
 

When painting on top of a previous layer of paint that had dried, I have occasionally come across a a small area that has seemed to dry with a particularly smooth finish, so that the new paint doesn't adhere properly to the canvas. I will apply some paint on top, but when I try to smooth out my brush strokes, the new paint glides away, and the old color shows through. I am concerned not only about getting it to look right, but also whether the paint layers might separate in the future.

Is there a good way to restore the tooth on the surface of the painting? I've thought of sanding, or spraying a workable fixative, but I hope I can get some advice before I mess it up.

Thanks in advance for any help.

You could sand the area lightly or spray it with just a bit of retouch Damar varnish. That stuff has a lot of "drag" to it that seems to really hold the paint. Paint into it about ten minutes after you spray it on.

Michele,

Many thanks; I will try your advice!

I've had the same problem in the past, especially after overdoing a retouch varnish following a long painting session.

I tried the organic solution, which consists of scrubbing an onion over the previous layer, and it works surprisingly well for grab and adhesion. I also found there are a few mediums that will yield 'bite' when laying down the next layer of paint, as well as providing a more desirable feel and (I am told) increase the mechanical adhesion between layers of paint: Canada Balsam and turps scrubbed thinly, Canada Balsam and oil scrubbed VERY thinnly, and even Maroger did the trick when a light coat is scrubbed in and allowed to sit for a short time. I imagine a number of alkyd-based mediums exhibit similar characteristics. Anyone know for sure?

Minh Thong