HELMUT RUHEMANN'S INPAINTING TECHNIQUES
Varnishes must protect the paint surface, must not darken, must be long-lasting and must be visually satisfactory.
I use MS2A throughout, or a Ketone Resin N if MS2A is not available, applied as a first coat by brush to give a saturating and protective coat. Further layers are sprayed, and a final wax polish is applied with a pad made of cotton velvet to protect the varnish against humidity and friction.
During the inpainting process, it is advisable to work on a fairly saturated varnish layer which brings out the original colors and thus facilitates matching.
Before he applies the final varnish, the restorer has to decide what visual effect he considers desirable for that particular painting. As a general rule a satiny sheen is to be aimed at, but dark paintings are flattered by a somewhat shinier varnish than light ones, and highly textured surfaces must be kept a little more mat to avoid sparkly reflections.
The degree of shininess of the varnish applied with a spray gun is a function of the following variables, and changing any one of them will change the appearance of the varnish surface:
Viscosity of varnish
thicker = more mat.Temperature of varnish
colder = thicker = more matSpray gun nozzle opening
smaller opening = smaller varnish droplets = more matDistance of nozzle from painting
greater distance = drier varnish droplets = more mat.