Troubleshooting

Topic List:

Priority:

  • delamination
  • craqueleur
  •  buckling
  • fading colours / lightfastness. You need to worry about the lightfastness of organic materials.
  • problems with varnishing, results in patches/stains of semi-gloss

Minor issues:

  • brushes, cleaning
  • studio lighting
  • self-portrait setup

Yellowing Of Oil Paints

In my experience, most of the yellowing we see in old oil paintings is in the old varnish, and once that is removed, the yellowing of the paint itself is usually negligible, unless the painting has been recently stored in a dark place.

Linseed oil paints do yellow somewhat, but the yellowing is a temporary phase they go through that eventually reverses if the painting is exposed to light. That being said, the Old Holland Cremnitz White samples on my test panels yellow more than the others on the same panels, and remain yellower for a longer period of time. My guess is that this is due to their stabilizer, hydrogenated castor oil, which the manufacturer doesn’t want us to know is in there.

My personal feeling is that concerns for yellowing of oil paints are overblown, because the initial yellowing of linseed oil paints reverses with exposure to light, as I mentioned in my book. If the painting is kept in darkness, the yellowing will return, but will bleach out again if the painting is returned to the light. How fast these changes occur depends on the strength of the light the painting is exposed to.

Loose Canvas

Using stretcher or corner keys to tighten loose canvas on stretcher bars is not a best practice.

“The problem with using corner keys to tighten slack canvas is that it creates uneven tension, tighter in corners than anywhere else, because the staples or tacks along the sides are still the same distance apart from one another. This seems to work well enough in the short term, but can create problems after the canvas is no longer new. A better practice is to remove all the staples or tacks, and re-stretch the whole thing, using copper tacks instead of staples. Better still, glue the canvas to a rigid panel.”

White Spots on the Canvas

Symptom: White spots on a canvas that has been stored in a damp studio.  Could it be bloom or mold? How should one deal with it?

Virgil’s comments: 

The white patches could be bloom instead of mold. This is something conservators have started finding recently in oil paintings from the 1960s and newer. It’s suspected as being caused by aluminum stearate, a stabilizer that most brands add to their oil paints to prevent the oil and pigment from separating in the tube while the paint is waiting to be used.

If the spots are mold, try brushing them off with a clean, dry, stiff hog-bristle brush, while wearing a mask to prevent inhaling any mold or spores that become dislodged. The best advice, however, is to take it to an AIC-certified conservator.

Resource: American Institute for Conservation