Foundations for Gilding Part III: The Finish

© Amanda Quinby

This is the last of a three part series on the basics of gilding. While not strictly part of the gilding process, finishing- toning and antiquing – is essential to completing a newly gilded frame. Only rarely can a work of art hold its own to an untoned gilt frame. The leaf, whether precious or base, is typically too bright and visually overpowering without at least some toning down. And it is, after all, what is inside the frame that is meant to be noticed, complimented and made to stand out.

I divide finishing into two categories; toning new or newly regilded frames and matching repairs to an existing finish. Of the two, toning a newly gilded frame is the more straight forward. Assuming the need for at least a somewhat antiqued finish I begin by rubbing through the leaf using either 000 steel wool for oil gilded surfaces or rottenstone on alcohol moistened cheesecloth for water gilded frames. Rottenstone is a finely powdered limestone. It is gray in color and useful in nearly every step of the finishing process. The rub through should be just enough to give an impression of age and some wear to the finish. It should bring up some of the colored undercoat without making that color too dominant. The frame is then coated with a thin layer of shellac. Shellac tends to bring out the rub-through so it important not to over do it.

Shellacs come in a variety of colors depending upon degree of refinement, from super blonde which appears almost clear, to orange and button shellac which is amber. I use super blonde most frequently but  I use button shellac to warm silver and 12k gold finishes and to give a more aged look to some gold finishes. As always, the look of the original finish and the art work to be framed are the determining factors in these choices.

Many aged frames have been subjected to any number of distresses over the years including storage in attics and old barns. This often results in speckling of the finish from insects, molds, or tarnishing of silver or dutch metal leaf through pinholes in the shellac. In an effort to recreate this look I often spatter frames with a concoction of thinned button shellac, a pinch of rottenstone, and either raw umber or black powder pigment. Using a small, stiff brush, I lightly spatter or “fly speck” the frame. Like rubbing through, fly specking is most effective when lightly applied, the effect being almost subconscious rather than overtly noticeable.

The next choice is the actual finish. I most typically opt for a light raw umber casein wash for antiqued frames. Casein is a thick, water soluble, milk protein based paint. It is commonly used on theater sets and dries to a flat finish. I thin the paint to a watery consistency and, after brushing it onto the surface of the frame, use a natural sponge to remove any excess and to eliminate brush strokes. The resulting finish is visually soft. I then brush the highlights lightly with steel wool to remove most of the remaining casein, thus creating a play of light between highlights and shadow on the frame.

Casein will, over time, cure to an extremely durable finish, impervious to most efforts at removal. When newly applied, however, it is vulnerable both to water and simple handling. I therefore coat most newly finished frames with a light layer of wax, thinned with mineral spirits. This coating can be tinted with an oil based toner to further color the finish, as necessary. The wax serves first to protect the finish. Secondarily, it provides a sticky surface to which a light dusting of rottenstone can be applied. This dust, tinted or not, is then brushed off, leaving a hint in the crevices of the ornamentation, typical of an antique frame.

There are, of course, many ways to tone or antique a frame. For example, I sometimes use oil based toners or glazing compounds alone. The final effect is less soft than that achieved with a casein wash but that is, at times, appropriate. But I have found the use of casein to be the most versatile and evocative of the decades of accumulated age typical of an older frame.

Toning a repair to match an existing finish is an entirely different process. Blending old with new is almost always a challenge. The most important thing is to match as closely as possible at each step. The new gesso should be as smooth as the original gesso. I always use rabbit skin gesso and bole rather than acrylic out of respect for tradition but also because the burnish is different with these newer, synthetic products.(see Foundations for Gilding I and II for discussion on bole and gesso.)

It is important to match the bole color as closely as possible then gild with whatever leaf is closest in color to the existing finish. As for a new frame, the new finish will probably need some distressing. I usually use rottenstone and alcohol but sometimes steel wool or even sandpaper is the most effective means of matching to the existing distress.

At this point, when I’m lucky, the application of the appropriately colored shellac is all that is required to achieve the correct finish. But that happens only rarely. Usually the new finish is built up in subtle layers – shellac, casein, toner, in that order and, along the way maybe mixed with some powder pigments or mica powder. I can stop at any point that I feel a match has been achieved or, and this is important in conservation work, remove whatever layer does not work.

After I have the best match I can get, I look at the dust and soot that is in the grooves of the original sections of the piece and match that color with a combination of rottenstone and powder pigments. Unless my client wants a new looking frame, the presence of some dust in the crevices is typical and appropriate for an older frame. The application of new dust helps to tie old and new elements together.

These are the basics of my techniques for gilding antique frames and reproductions. The truth is, however, that there is no strictly correct way of achieving an antique look.  I’ve used watercolors, thinned japan colors and tinted shellacs or, in the words of one of my mentors, “whatever works.” To an extent I follow his advice but keep in mind the need to respect the art to be framed, the frame itself, and always, the tradition that is the foundation of the gilding craft.