What about rabbit skin glue?

[Josef Sy]

Hi Jean,

If there is sizing then it is ok. RSG, gesso acrylic or classic. It is a problem when there is no sizing at all. It is when the fibers are in direct contact with oils and mediums that causes chemical reactions which will weaken the fibers.

[Steven Sweeney]

Just in passing, I note these remarks from the Gamblin site, discovered on an unrelated pearl dive:

SIZE

Before a oil painting ground is applied, the canvas is sealed with a size. The size seals the porous fabric and isolates it from the ground and/or oil paints. Linen and cotton will prematurely rot without a size layer. Only fabric supports need sizing. Panels only need to have a ground. Acrylic gesso does not require a size.

PVA Size (poly vinyl acetate glue), diluted with distilled water, is a contemporary size for fabric support. Conservation scientists recommend painters use neutral pH PVA size on linen and canvas instead of rabbit skin glue. PVA provides a good size layer that seals the fabric but does not re absorb atmospheric moisture, swell and shrink like rabbit skin glue does. Painters who want to paint directly on a size, apply one layer of PVA Size to the front and back of the fabric.

We acknowledge and appreciate the research of the Canadian Conservation Institute that helps painters and conservators identify the best PVA to use.

Rabbit Skin Glue is the traditional size for fabric support. Conservation scientists caution painters that rabbit skin glue absorbs atmospheric moisture on damp days and swells; gives off moisture on dry days and shrinks. This movement of the size layer can cause aged oil paintings to crack, according to the Smithsonian Center for Materials Research and Education

[Jean Kelly]

Thank you Steven, this is the kind of info I was looking for. It may explain why my old paintings have cracked. I still have two very old paintings from my college days and both have cracked severely. Along with the fact that I have done nothing to protect them, they were all sized with rabbit skin glue.

Jean