MITRA Forum Question Details

Having not tried the Rublev ground I can't speak to its performance, but just in general, the sizing shouldn't significantly alter the absorbency of an oil ground. If the support is correctly isolated, it should not wick away so much of the primer vehicle as to alter its standard characteristics. ​Regarding which sizing approach to use: imparting stiffness is an important function of the sizing, because it helps stretched fabric maintain a flat plane, which in turn reduces stress on the ground and paint, so the addition of GAC 400 sounds like a good plan.

A size is an application of a material used to cut and even out the absorbency of a support. This concept can also be applied to the application of a non-pigmented material used to cut the absorbency of a ground. A size should partially fill in the minute cavities of the support or ground but not be a continuous discrete layer. This could make the surface too non-absorbent and could promote delamination.

A ground is a covering layer which generally contains some sort of filler and tends to be opaque. This should have the optimal degree of absorbency for the proposed paint medium. A ground can be smooth or textured. Generally, the smoother the ground the more absorbent it need to be to promote good adhesion.

The definition of a primer is a little more ambiguous. The more precise use of the term is the application of an oil-containing pigmented layer to an aqueous ground layer to cut absorbency, often lock in the underdrawing, and sometimes provide a uniform color other than white. This is often called an imprimatura, although many commentators would only use that term for such a layer in Italian paintings. Despite my opinion on the matter, the words ground and primer are used interchangeably today.  Don’t get me started on the misuse of the term “gesso” ;)

In the art materials industry, the term "priming" means a transitional layer which makes a substrate receptive to paint. The primer adheres durably to the support (usually better than paint alone), hides the support material, and creates a uniform surface with optimal properties for paint adhesion.