by Michelle La Bonté Kelly (Artist Educator for Winsor & Newton)
Sinking in, paint that goes dull, matt and chalky creating a visually inconsistent surface, is problem frequently encountered by painters. Though many of us are most familiar with this happening in oils, it can also occur with alkyds and acrylics.
There are two reasons paint sinks in. The most common is mixing too much solvent into paint. I use almost no solvent in my paint, and would never use more than 10-20%, and that only for the first thin underpainting. I recommend using a good quality medium to thin the paint. They give the paint flow but won’t sink in and will create a more stable, archival paint film.
Sinking in also occurs when a ground is too absorbent or unevenly absorbent. These grounds will draw oil out of the paint leaving behind a matt, more fragile surface that looks lighter than the surrounding colors. This is not good for the painting and makes it hard to match the next layer of paint to what is already on the canvas or panel. Using house primers as grounds, cheap gessos, too little, or over-thinned gesso can create an overly absorbent or uneven ground.
To prevent this use a high quality gesso or ground, never thin more than the manufacturer recommends, and don’t take the shortcut or false cost saving measure of using too few coats of ground. The Winsor & Newton gessos are my favorites because they are easy to brush on and leave behind a beautiful surface with plenty of tooth to keep my paint firmly grounded.
I primarily paint on untempered Masonite panels. I haven’t had problems with sinking in with a high quality acrylic gesso but I have sometimes encountered it when I use traditional rabbit skin glue gesso. Since I use Liquin as my medium, I now prevent this by rubbing a thin coat of Liquin over the glue gesso. The ground still retains more absorbency than an acrylic ground but the paint is less likely to sink in.
Is there anything you can do once paint has sunk in? Absolutely. If you are still working on a painting, you can apply a little retouch varnish to the area of sunken color. It will bring the gloss back up so you can readily match the color again. Be sure to only use retouch varnish, never any other kind of varnish for this job.
You can also use a little Winsor & Newton Artists’ Medium in the same way. It contains no varnish and so it will actually help stabilize and better protect the sunken paint since it is not removable. Varnishes are always to some degree removable so if a painting is cleaned where only retouch varnish is applied, some of the original paint may be removed too. I prefer the Artists’ Medium for restoring areas of sunken paint. It may be applied more than once if needed.
If you don’t apply the Artists’ Medium or retouch varnish to areas that are dull, subsequent layers will continue to sink in. It is best to correct sinking in when you first notice it.
If you prefer retouch varnish to restore sunken color while working, or whenever you have a painting that has varying degrees of gloss when you are finished, you should “oil out” the painting prior to varnishing. This is a simple process of rubbing a layer of Winsor & Newton Artist’s Medium over the entire painting with a lint-free cloth. This may be done when the painting is dry to the touch. A six to twelve month wait is still required prior to final varnishing.
Oiling out will prevent the paint layer from being removed when a varnish is removed for cleaning and it will give the surface a consistent sheen. Varnish alone will not do this. Matt areas will become glossy but glossy areas will be even glossier. So the simple step of oiling out will ensure that your work is always looking its best.
There is an excellent demonstration on how and why to oil out a painting on the Winsor & Newton website at:
You will find a demonstration on how to varnish on the same page.
There is also a very helpful Resource Center on the site which includes answers to frequently asked questions, videos of techniques and artists at work, and “The Oil Colour Book” a free downloadable guide that concisely covers many properties of oil paint and painting that we encounter in the studio.