Q. I take great care in selecting the best papers for my mixed-media paintings. Is there anything in the media or supplements I use—oil pastel, wax crayons, wax or other resists, alcohol, ox gall, salt, vinegar, honey, etc.—that could damage my paper? Can I prevent any problems with a layer of gesso or neutralizing liquid?
A. When using a varied and mixed technique, there are few sure ways to predict the aging of the work of art. The safest painting techniques are typically the simplest, and by that I mean keeping additional mediums—and other additives—to a minimum. Mixed-media works may survive in good condition, but often these works will age in ways you might not anticipate. If youre the type of mixed-media artist who enjoys the element of accident and surprise in your work, that might be OK, too. Robert Rauschenbergs works are a prime example of bringing together very different elements. Its true that many of the materials he uses, such as newspaper, are fragile, and that over time theyve changed. But these changes havent diminished the meaning of Rauschenbergs art, making him one of the recognized masters of our time.
Of the materials that you use in your work, keep in mind that oil pastels and wax crayons are sometimes made with fugitive (non-lightfast) pigments. In addition, oils used in your pastel work may leach (seep) into the paper support, staining it and eventually making it brittle—even if you use rag paper. Waxes range from hard to soft and are generally stable, but keep in mind the softer varieties can attract dust while the harder types can crack on flexible supports like paper.
In terms of your other materials, alcohol is a volatile solvent that I assume you use as a diluent. Since alcohol evaporates, it poses no hazard to your paper. But if you overuse any diluent, however, you can undermine the binder in your media, which creates a dry and fragile surface. Using ox gall as a wetting agent in small amounts should pose no problems to your work.
Im not familiar with using salt or vinegar for painting. If youre mixing these materials in your media I can only guess that high humidity could possibly draw salt crystals out of your paint, potentially causing cracks. Vinegar is acidic and may degrade the paper. Historically, honey has been used in small quantities in the making of watercolors to keep the cakes moist. Today glycerine is used in aqueous (water-miscible) paint formulations. Still, I dont recommend using honey in large quantities because it remains reactive to moisture.
As for preparing your paper, a ground layer can isolate your mixed media from the paper, but not without problems of its own since it can be quite fragile. An oil ground shouldnt be used on paper because the oil itself will leach into the paper, and stain and embrittle it. As well, many aqueous grounds, like glue grounds, will easily stain. Flaking and loss of the ground has also been a problem with paper since expansion and contraction of the paper often jeopardize the adhesion between the two. Your best bet for keeping a ground layer from cracking and flaking is to use a rigid paper board.
Finally, commercial sprays and liquids have been developed for deacidification or “”neutralization”” (making the paper acid-free). These products arent without their problems, either, since they can darken both the paper and pigments used in your artworks, dissolve some inks, and create spotty areas if theyre absorbed into or applied to your artwork unevenly. If you use good quality rag paper, then youre starting with a paper with a neutral pH. If your art is then matted and framed with good quality rag boards that are also neutral, you should be able to maintain a stable paper support. To further ensure the longevity of your works of art on paper you can mat and frame your work with buffered rag board thats been treated with an alkaline substance so that you start off with a basic pH that will help act as a further acidity barrier.
Of course, its always best to create your work with the best materials possible. So use rag paper to ensure that youre starting off at a neutral pH. Remember, though, that even rag paper can become acidic if the materials you use are acidic or if you frame your work with acidic materials. You need to stay open to the possibility of unanticipated change if you want to work with mixed media.
Heather Galloway is a freelance conservator living in northern Ohio.