Medium for an isolating layer

What may work as an isolating layer between the priming and underpainting / and between underpainting and overpainting? Retouch Varnish / Liquin/ acrylic varnishes/ Damar Varnish? Any recommendations, guys and Why?


  • edited July 2021
    Norman Rockwell used shellac to isolate the drawing he did on the canvas from the paint he put over it.  I read this in a book about him.  Mostly, he did this when he was hurrying to meet a deadline.  It allowed him to scrub down to his drawing in the event he lost his way.

    The other things you mention as possibilities are generally considered part of the painting process, and they would most likely become part of the painting rather than a barrier layer.
  • dencaldencal -
    edited July 2021

    If using a wooden panel or canvas gesso (2 or 3 layers) will work well between the primer and under painting.

    When the under painting is dry go straight on with over painting. No need for an isolating layer.

    Hold back on any type of varnish ‘ til the final protective coating in six months.

    Try using Mark’s DMP method of direct painting in one layer on to a simple drawing. This is directly on to the toned gesso surface. Much simpler and faster than the ‘Flemish’ method.

    When using shellac or polyurethane as sealants, artists should consider the following:
     Avoid using them with fabric or paper supports.
     Use them to seal wooden supports only if they are unable to use other products (e.g. PVA, acrylics). Shellac and polyurethane are less than ideal materials in terms of reversibility, brittleness and ageing characteristics.


  • Rockwell was painting on deadline.

    Retouch varnish spray works or Kamvar. Or just let the painting dry. 

    Shellac is good for Heavy Paper or Illustration board as a primer. 
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