HELMUT RUHEMANN'S INPAINTING TECHNIQUES
12 TYPES OF DAMAGE IN AN OIL PAINTING
Oil paint is subject to many kinds of damage which need to be inpainted. The following is a list of those found frequently with suggestions on how to deal with them, as shown on Plate 5.
Wear and apparent wear:
This is due to the original paint having been abraded or become more translucent with time.
In canvas paintings wear results in innumerable dots of underpaint or even ground color showing wherever a thread of canvas over-lies another. I know of no other way to deal with this except to inpaint each dot individually, usually in a translucent medium for a reasonably luminous final effect.
Wear in panels usually reveals dark short streaks of woodgrain, especially in thinly painted areas such as the skies of Netherlandish 17th century landscapes. It is difficult to paint out the streaks without making the sky look heavy. The most successful method I know of is to use a very light first layer which is then glazed down to the sky color.
This is due to shrinkage of the paint layer. The wide, bitumen type may have to be treated like a damage. If necessary, the underpaint may have to be inpainted in a covering medium, and the crack in the design layer in Paraloid B72.
Fine cracking should be accepted as part of the nature of the painting. If it is too obtrusive it can be made less disturbing by tactfully interrupting the worst cracks with a few fine short lines of inpaint. Similarly some intersections of two or more cracks can be just touched with inpaint, on the theory that the pattern of cracks is densest there.
12.2 Missing Glazes
If glazes are missing they are likely to have been very thin and can be replaced with transparent pigments in a transparent medium.
12.3 Missing Highlights
Missing highlights can be scumbled in using the most viscous, driest possible Paraloid B-7 rubbed on with the heel of the paint brush. An area of stained original paint can be treate in the same way without making it look overpainted.
12.4 Alien Color
Patches of alien color, such as traces of old overpaint which cannot be removed safely, o fly-specks, or small stains, should be given a covering coat of underpaint, and then glazed with the design layer color in a transparent medium, as shown on Plate 6.