July 19, 2008
The Art of Glass Gilding
By Hingst, Jim
All the details about gold leaf gilding on glass surfaces. "Have you ever seen glass gilding done before?" Bob Behounek, one of the founding fathers of the Chicago Brushmasters, recently asked me.
I had done surface gilding before, which is relatively easy to do. What I was to learn was that gilding glass was a completely different process. This technique was a little more complex, requiring a much gentler artisan's touch and some specialized tools. In this article, I will describe the tools and step-by-step procedures used to apply gold leaf to glass.
Bob's sign, which celebrated the Chicago Blackhawk's 1961 Stanley Cup Championship, was nearly complete (after months of work). The gold leaf for the sign was donated by Wehrung & Billmeier Co. (www.wandbgoldleaf.com) in Chicago, Illinois.
The design incorporated a black outline, which had been screen- printed first using Nazdar inks on the backside (second surface) of the sign. Behounek decided to screen print the black, because it would deposit a dense uniform layer of ink on the glass surface without any brush marks. The other colors of the design were painted using 1-Shot lettering enamels.
The finishing touch was to gild the glass. Glass gilding is done on the second surface of glass. Because the graphics are viewed through the first surface of the glass, any lettering must be done in reverse.
Tools of the Trade
Brushes that are used for gilding should only be used for that purpose. To protect your brushes and other tools from contamination, you can store them in a plastic container. You can buy plastic boxes used to store fishing gear for your gilders supplies.
Joe Balabuszko of supplier Earl Mich Company (www.earlmich.com) also recommends setting up a kit expressly for gold leaf work. Tools for glass gilding include a gilder's knife (a specialized knife with a straight blade and a squared-off tip used to cut sheets of loose gold leaf into smaller pieces), a gilder's cushion (used as a cutting board for gold leaf,), and a gilder's tip (a three-inch- wide flat brush used to transfer sheets of gold leaf to the work surface).
In his definitive book on gilding, Gold Leaf Techniques, Kent Smith advises washing your oily or dirty gilder's tip with shampoo and water. After hanging it up to dry, he suggests combing the hairs. Who needs a cat or dog, if you have a gilder's tip? Smith also recommends storing the glider's tip between two pieces of corrugated board.
You'll also need loose gold leaf (either 22- or 23-karat and regular or the thicker glass), gelatin water size (a clear adhesive that bonds the gold leaf to the glass), a flat wash brush (used to apply water size when gilding), 1-Shot lettering enamel or Japan black (used to back-up the gilding and/or painting outlines and drop shadows), varnish (which protects the gilding from abrasion and moisture), and cotton balls or a mop brush (to remove any excess).
Prepping the glass properly is critical to achieving good adhesion of the gold to the window. Any type of contamination on the glass could later result in the leaf flaking off of the surface.
In most cases, sign makers can't pick the surfaces they're gilding. Be aware, though, that water size and paint will adhere better to an old window than a new one. According to Smith, one reason is that, with wear, the surface of old glass becomes more pitted and scratched. (Note: This gives the glass more tooth for the size and paint to adhere.)
New glass can also have contaminants on its surface . These contaminants must be removed for good adhesion of the gold leaf. Failure to thoroughly clean the glass can result in chipping and peeling of the gilding.
Many glass cleaners (such as Windex(R)) contain silicone. Don't use these to clean windows. The residue these cleaners leave behind will cause problems with the gold leaf adhering to the glass.
Sign makers have developed a variety of cleaning concoctions and ritualistic procedures for prepping glass. The procedure for removing contaminants from glass is very similar to the way that a vehicle should be cleaned before applying vinyl graphics or pinstriping.
Smith recommends cleaning the glass surface with a wax-and- grease remover. These solvents can leave an oily residue that should be wiped off with isopropyl alcohol (IPA).
After solvent cleaning, Balabuszko recommends rubbing a bar of cake Bon Ami (not powder) against a clean, damp rag to build up a good lather. Cleaning the glass with a mild abrasive such as Bon Ami will give the glass a little tooth. This cleaning step is always performed twice. (Note: An alternative to using Bon Ami is to clean the glass with a mixture of soap, water, and ammonia.)
Balabuszko then uses a single edge razor to scrape any of the glass that will be gilded. Quite often, the surface of the glass could have tiny specs of paint and other contaminants that you can't see.
Finally wipe the surface clean with isopropyl alcohol (wiping it two or three times). This will clear off the slight haze that the Bon Ami leaves. "You can be confident that the glass is clean, if you wet it and the water doesn't bead up on the surface," says Balabuszko. "If it does, keep on cleaning."
Laying Out the Design
Screen printing an outline is one way to engineer a glass gilding job. A more common technique is to pounce a pattern on the window. After painting the outline, you can gild the areas inside it.
The next step involves backing up the gold with a mixture of Japan paint and varnish. Japan paint is used instead of lettering enamel here because it dries faster. The excess leaf is then washed away. (Note: If you haven't developed the skills of hand-lettering, you can also cut a paint-mask stencil using a product such as R Tape's ProGrade(TM) paint mask to paint an outline and drop shadows.)
Another common way to layout the job is to apply the gold leaf directly to the glass. After the gilded area is dry, pounce the design over the gold leaf. After backing up the areas with paint, clean off the excess.
Mixing the Size
For surface gilding, sign makers will generally use an oil size. In gilding glass, a water size is used. Balabuszko recommends preparing your water size just before gilding. He also says that you should only mix the amount that you'll use. Water size doesn't keep well, so don't store any of the unused mixture.
For Bob Behounek's Chicago Blackhawks sign, two OO gelatin capsules were dissolved in a pint of distilled water. Balabuszko emphasizes keeping this can clean and using only distilled water to prevent any contamination that could cloud the gold.
Heating the water dissolves the water-clear gelatin. Balabuszko dissolves the capsules in a stainless steel can, which he only uses for this purpose. After the size dissolves, it isn't necessary for the water to stay warm (but it helps, because the warmer the water, the faster it dries).
Balabuszko recommends avoiding any potential fire hazard by using an electrical heater. After heating, the size should be strained. Regardless of which heat source you use, you must warm the water to dissolve the capsules. Balabuszko cautions not to boil the water. (Boiling can cause the dissolved gelatin to harden as the water evaporates.)
Capsules aren't the only way to buy gelatin size. It's also sold in sheets divided into diamond-shaped pieces. As a rule of thumb, you'll generally use two diamonds for every 00 gelatin capsule.
More isn't always better when mixing up a batch of water size. In most cases, you should resist the temptation to add extra gelatin capsules to your mixture. Sure strong mixtures create a strong bond to the glass-sometimes too strong, when it comes time to clean off unwanted gold from the glass. Balabuszko also says that too strong a mixture can become hazy over time, thereby lessening the brilliance of the mirror finish. Too weak of a mixture of size, though, is worse than too much. A weak mixture can result in the gold leaf chipping and peeling.
Applying the Gold Leaf
After the glass has been cleaned, it's time to apply the size. Whereas oil size used in surface gilding is the consistency of paint and is applied only to the area to be gilded, water size is "watery" and is applied to the glass above the area to be gilded. The water size is applied with a special brush (called a flat wash brush or size brush), which allows a steady stream or sheet of size to flow or run down the side of the glass.
In applying the size, don't hold back. Liberally brush on the size above the area to be gilded so that it streams down the side of the glass. Balabuszko first floods a coat of size over the entire area and then reapplies the size to the area that he's working on.
Gilding glass isn't generally affected by the weather because applications are done second surface on the inside of the window. Sub-zero temperatures can be a big problem though. If ice forms on the inside of the window, there's nothing you can do other than wait until temperatures rise. "At extremely cold temperatures, the water size will freeze, and the gold just won't stick," explains Balabuszko. (Warning: Heating the window with a torch or heat gun will crack the glass.)
After wetting the glass surface, the next step is to apply the gold leaf. This process requires that you learn how to use a gilder's tip. "The old-timers would brush the gilder's tip against their hair to pick up some oil," says gilder Eric Elmgren. "The oil on the hairs of the brush would stick to the gold, so you could put each piece in its place. Unfortunately I don't have much hair anymore, and what little I have left, I don't use any stuff on it." Elmgren suggests that an alternative way to use this brush is to first apply a small amount of brush oil or vaseline intensive care to your arm. Brush the gilder's tip against the oil on your arm and then touch the gilder's tip against a sheet of gold leaf. The tip will lift the leaf from the paper so that you can transfer it to the glass.
In laying sheets of gold leaf in place, Balabuszko comments that more right-handed people prefer working from left to right (to avoid leaning against their work). Left-handed gilders, however, should lay the leaf starting from the right and working left. Regardless of the sequence you use in laying leaf, Balabuszko advises that you minimize the number of overlapping pieces as best you can, so as to minimize any noticeable seams in the gilding.
In applying the leaf, Balabuszko starts at the top of the letter and lays subsequent sheets below the preceding ones. If the gold leaf doesn't lay perfectly flat, blowing on the gold leaf can help smooth the sheet. "Watch what you're doing when you apply a second wash of size," advises Balabusko. "Too much wash and your gold can slide down the glass. Once that happens, it's virtually impossible to put the leaf back in place.
"If the gold leaf starts to slide out of place, you can sometimes stop the slippage by blowing on it. Touching the leaf with the gilder's tip for a second can also help secure the sheet in place."
Applying a second wash of water size generally will also brighten the luster of the finish and strengthen the bond of the gold to the window. Often when the gold leaf is first applied over the water size wash, it'll appear satiny through the first surface of the glass. Not to worry: As the size dries, the gold will tighten up, and the finish of the gilding will become glossier. "Don't fret about any small wrinkles," counsels Balabuszko. "They're inevitable. Most won't even be noticed when the excess gold is brushed away and patched."
You won't necessarily want to use full pieces of gold leaf, if a smaller piece will do the trick. Gold leaf can be cut into smaller sections. To do this, use a gilder's knife and a gilder's cushion.
After the gold is dry, brush away the excess leaf with a cotton ball, powder puff, or mop brush. If you use cotton, be very careful: It may feel soft, but the fibers are coarse enough to abrade away the gilding from the glass. A squirrel or badger mop brush may seem to be an expensive tool, but it's a worthwhile investment. Because of its softness, it's much safer to use.
After removing the excess gold, inspect your work for holidays (voids in the gilded surface). There are two ways to repair any holidays: You can either apply more size and gold leaf where it's needed, or you can do a second gild. Often Balabuszko will double- gild a glass sign, so the gold is extra-thick.
Performing a second gild produces a high-quality job. Balabuszko cautions, however, that you should make sure you're charging enough for the job to cover the additional time and material that's involved.
To give the glass gilding a high-polished finish, some sign makers will apply a hot wash to the gilding. To do that, dilute the amount of size by 50 percent to make it half strength and then reheat it. Washing the back of the gold with the hot size tightens up the gilding and gives the gilding a mirror finish. "Many gilders don't advocate using a hot wash," says Balabuszko. "Some people just don't like the highly polished surface, because it looks as if the gold has been sprayed on. Others feel that the hot wash potentially weakens the adhesion of the gold to the glass."
Balabuszko uses vertical strokes in doing a second gild (applying the size directly to the gilded area). "I do a onceover with the size, and then I leave it alone," he says. "If you overdo it, you'll weaken the gilded area."
Backing Up the Letters
After you've gilded the glass, back up the gold with Japan paint. Smith recommends adding some varnish to the mix. "The higher the concentration of varnish to paint, the tougher the paint will be," he explains. (Note: Ratios of Japan paint-to-varnish can vary between 1:2 to 1:4. After mixing the components together, be sure to strain the mixture to eliminate any paint globs.)
If worse comes to worse, back up the gold leaf with 1-Shot black lettering enamel. You can improve the flow out of the paint and achieve a nice, shiny finish similar to a lacquer's gloss by adding a paint conditioner (such as Penetrol). Anything that's not protected with paint is then washed away with a damp brush.
Black isn't the only color that you can use to back-up the gild. Gilders have also used yellow and terracotta red. Each color used to back up the gold imparts its own tone. "Black makes the gold bold," says Balabuszko. "Yellow makes it mellow, and red gives it a rosy appearance."
Make sure that the paint is thoroughly cured before removing the excess gold. Paints dry faster during warmer summer temperatures and more slowly when the weather is colder.
After gilding, you can then paint a drop shadow. Remember that glass gilding is done on the second surface, so you'll have to do everything in reverse.
After this eradication process, the window graphic should be protected with a coating of varnish. Balabuszko says that there are all types of varnishes that signmakers use for glass gilding: Spar Varnish, Commonwealth Clear, and gloss polyurethanes. "My advice is to try the different products and see what works best," he suggests. "Once you find a winning combination, continue to use it."
Sign painters protect gold leaf with varnish to provide abrasion resistance and to prevent exposure of the metal from air (which can oxidize the gilded surface). For glass gilding, the coating of varnish also protects the size from any moisture that could attack the size. Remember that water size is water-soluble. Although you can use most varnishes to protect your work with no problem, some volatile solvents can attack the size.
For many applications, a gold mirror finish is just what the doctor ordered. Gilder Ron Jelinek says that there are a number of different tricks that you can use to give glass gilding some texture and some visual interest. "Water size is used, because it's crystal- clear and produces a brilliant, high-gloss gild," he says. "If you're trying to create the illusion of a dimensional letter (such as a chiseled font), you can give one facet of the letter a matte finish and other parts a gloss finish. To give a part of the lettering a matte finish, apply an oil size to those areas. Fast size is excellent for this application because it dries fast.
"Unlike the water size, an oil size isn't perfectly clear. Water size produces a mirror finish. The oil size disperses light (creating a matte appearance). Tinting the oil size with a couple of drops of lettering enamel can also create an interesting effect."
Jim Hingst Jim Hingst (who also happens to be R Tape's business development manager) has over thirty years of quality experience in the graphic arts market. His career includes a range of activities- including product development, estimating, production planning, vinyl application, and sales and marketing. Jim has contributed more than 120 articles to many of the leading publications in the sign industry and is also the author of the book Vinyl/Sign Techniques. This month, Jim steps away from the vinyl and ventures into some new territory for himself: the art of gold leaf gilding on glass and windows. These types of exquisite signage are extraordinary, and if you've ever wondered about the tools, skills, and techniques you'll need to accomplish this type of work, turn to Jim's "Hingst's Sign Post" column that begins on page 34.
Copyright Simmons-Boardman Publishing Corporation Jul 2008
(c) 2008 Sign Builder Illustrated. Provided by ProQuest Information and Learning. All rights Reserved.