April 16, 2003

Dear Ms. Pech,

Regarding varnishing watercolors, the first issue is to understand that once the watercolor is varnished, regardless of the type of "varnish", you no longer have a watercolor - it has been turned into an acrylic. Watercolor pigment is very loosely bound, allowing the light to bounce off the various facets of the pigment, thereby giving the painting the sparkle characteristic of watercolors. Applying a "varnish" coating saturates the paper and surrounds the pigment particles, holding them in the new coating, which has now become the binding media for the painting. If the new coating is water based such as an acrylic dispersion, then several things happen. The pigment is now bound to the paper by the acrylic dispersion and more importantly, the refractive index is dramatically changed, resulting in a change of the values in the image. Needless to say, the character of the paper is also changed. These changes cannot be reversed. If a spirit-based varnish is applied over this layer, while the later coating might be removed, you still do not have a watercolor but an acrylic impregnated image. 

(note from Arleta- I don't use a sprit-based varnish)

Watercolors were varnished in the 18th and 19th century so they might pass as oil paintings and sell for more money. There was no consideration for the longevity of the work or art.

The issue is not the removal of the final varnish but the long-term change in the original watercolor. One of the values associated with watercolor painting is the luminosity and sparkle imparted by the loosely bound pigment and the white paper. While it may be possible to remove the upper varnish coating, one cannot separate the acrylic from the watercolor image or remove it from the paper without damage.

Why not paint in acrylics? Acrylics no not have to be exhibited under glass, especially if you first apply an acrylic gesso ground to protect the paper support. Golden makes and absorbent acrylic gesso that may be used with their fluid acrylic paints in order to achieve watercolor-like results.

As for mounting on Gatorfoam, the surface paper is impregnated with urea and although it might be acceptable as a framing material, it is not a product that is intended as a permanent support for a work of art.

(Note from Arleta- I use 8 ply museum board not any type of foam board)

In summary, I do not think the process of dry mounting a watercolor painting on paper to Gatorboard and coating the surface with an acrylic medium is a durable procedure and it certainly does not preserve the qualities for which we admire watercolor paintings.

Sincerely yours,

Ross Merrill

Chief of Conservation

National Gallery of Art

Washington, DC