More about drying in.

• Corot, courtesy; artrenewal.com

I will return to the posts on color soon. I get e-mail questions and I thought I would answer a few of those.

Dear Stape;
What makes some colors shiny and others matte after drying? I've noticed that some colors really shine and others are like a tiny layer of black hole sucking in available light. These is especially apparent when looking at the painting from the side. Is it medium, mixing, type of paint, ground? I read you said that Liquin could make it matte. Is that the only cause? Humm. A coat of varnish takes care of business but then everything is homogenized. I would love to learn to control this for it to do my bidding rather than my painting looking like a blotchy hot mess unless varnished.
signed; Matte

Dear Matte;

You have probably had the experience of working in watercolor and as the water evaporated the colors dulled. To some extent the same thing happens to oils. When the surface loses its sheen, less light is bounced back to your eyes and the colors appear dulled. Varnishing restores that sheen to the surface and the painting looks like it did when you painted it. This problem is called "drying in" and has a number of causes. They are:

• an overly absorbent ground. Try an oil primed linen, that might help.
• Some colors are more prone to drying in, Black, burnt umber and dark colors in general. Some pigments are able to suck up great quantities of oil. When that oil drops into the layers below it, you have a dried in spot.
  
• painting with thinner rather than a medium, there are lots of mediums but I use alkyds. Liquin gives a satin finish, Galkyd gives a gloss, and walnut oil-alkyd gives a very glossy finish. Varnish and oil mediums will help too, although I think they are more prone to drying in than alkyd.
  
• some drying in is probably unavoidable, it is just a part of oil painting. But it is easily remedied.
• Even if it is not dried in today, it will almost certainly dry in a little over the next year. So retouching a painting is a good idea anyway. Down the road you will want to get a real coat of varnish on it. Then the problem should be over.
  

There are a number of ways to bring back the gloss on the surface. If the painting is still wet, shoot it with retouch from a can or a mouth atomizer. Go easy, use too much and the painting might melt. Perhaps that is what happened to you. Used carefully this shouldn't happen. Don't put on so much that the varnish pools on the surface. Give it little thin coats so it dries quickly.

If the painting is dry, you have a number of options. You can polish the surface sometimes with a cloth or a pair of Ryan Seacrest's old nylon stockings. You can also "oil out" the painting. Put a small amount of linseed oil on a lint free cloth and put a very thin coat of oil on the pictures surface. Make sure the painting is completely dry first though. You don't want to smear those little spots of cadmium yellow that you thought were dry. You can also do this with Liquin or Galkyd, but remember, that is not a final varnish!