|GILDING ON GLASS
One of the most important steps in gilding on glass is to make sure that the glass is perfectly clean. Any traces of oil or grease, or even of a finger print, may prevent the gold leaf from adhering properly and may produce blisters. To make certain that glass is perfectly clean, wash with alcohol and then follow with Whiting and water. Then polish the glass with tissue paper. Exercise care to make certain everything else connected with the job is kept clean.
The first step in gilding on glass is to prepare a water size. The most popular water size is made by dissolving two or three No. 00 gelatin capsules in distilled water. The capsules should be separated and boiled for several minutes in a half pint of distilled water. After the capsules have thoroughly dissolved, another half pint of distilled water is added, and entire pint is boiled another minute or two. The resultant size should then be strained through a folded piece of clean cheesecloth, unbleached muslin or blotting paper. Size can be greatly improved by adding a few drops of grain alcohol or ether. This will help clear the size and help secure a better burnish and a clearer gild.
Apply water size. except when working in direct sunlight, while it is hot. Be sure that your size bucket and brush are thoroughly clean and free from grease. Both bucket and brush should always be boiled before using. Some sign men prefer to make their water size with Russian Isinglass or Fish Glue. A piece of isinglass about the size of a quarter, or an equivalent amount of glue, is all that is needed to make a pint of size. First boil in a half pint of distilled water, then add another half pint after isinglass or fish glue is thoroughly dissolved.
Method Of Procedure
The next step in gilding on glass is marking or laying out the job. Plain white chalk can be used for this purpose if the glass is first rubbed over with a damp chamois. However, a grease pencil is more reliable and will always show a distinct line. If a pounce pattern has been made for the job, the layout is pounced on with a small bag of whiting. A perforated pattern has a real advantage over marking with pencil or chalk for after a space has been gilded, you can pounce the pattern backward on the back of the gold where you can see the layout perfectly without having to look through the gold.
After laying out the job on the outside of the glass, the next step is to clean the inside of the glass. This must be done thoroughly in order to remove all oil, grease and finger prints. The entire inside surface covered by the layout should then be flooded with water size. This surface must be kept wet constantly (except the portion you have gilded) until the application of the gold has been completed. This is absolutely essential. If size is allowed to dry in spots, the result will be a poor gild with the gold showing a streaked, spotted appearance.
Start gilding at the upper left-hand corner. (If the workman is left-handed, this rule should be reversed.) This is done to prevent size running down over leaf already laid, also to avoid obscuring with your arm the completed work. Cut a strong piece of cardboard the exact size of the gold leaf book, and place this cardboard under the book to strengthen it while the leaves are being cut.
Fold back the first sheet of paper to expose the gold. Next, using the folded paper as a guide, cut the leaf by running your fingernail across the gold. Now you apply this piece of gold leaf to the glass. First draw a Gilder's Tip across your hair. Then with the Tip pick up the gold and lay it on the glass lightly. The gold adheres to the water size. Do not allow the tip to touch the size or the glass. Oil from the tip will cause the water size to creep away from the affected parts and produce a condition that destroys the luster of the gold.
Continue this process of cutting and tipping the gold to the glass until the entire design is covered with leaf. Allow each piece of gold to overlap the preceding piece about one-eighth of an inch. When the entire work is gilded, wait until it is perfectly dry before attempting to "Burnish."
As the gold is drying, the dry parts will present a bright appearance, while the parts that are still wet will be dull and without any luster whatsoever. Work that has been gilded but not finished should never be allowed to freeze. Frost and window sweating will completely destroy the adhesive qualities of the size. Consequently, the gold will come off when you burnish.
When the work is thoroughly dry, rub the entire surface with absorbent cotton or velvet plush. Rub briskly, but very lightly. This is done to remove the surplus or scrap leaf that did not adhere. At the same time it burnishes the gold and causes it to shine. After the leaf has been burnished, it is ready for the second coat, or what is called the patching process.
Regardless of the care taken in applying the first coat of gold, it is seldom possible to make a perfect job on the first gild. Burnishing the leaf reveals numerous small holes and imperfections in the leaf. These must be patched before the work can be backed up. Make certain that your burnishing cotton is soft and free from any dust or foreign matter. Small bits of grit will scratch the gold and ruin the job. While hospital cotton is slightly more expensive than ordinary absorbent cotton, it is absolutely free of all foreign matter, and is should be used to get the best results.
To patch the job, the entire surface must again be covered with the size. When doing so draw the brush lightly and quickly over the gold so as not to damage the gild already made. Most sign men dilute their size slightly at this point. This is to make sure the second sizing will not lift the gold already laid. Small pieces of gold should now be applied to the parts that need touching up or patching. When this operation has been completed, and the work is again dry, the gold should again be burnished lightly with cotton. The job is now ready for washing.
Washing is the process employed to give the gold a very brilliant burnish. For this purpose use clear water heated to the boiling point. Apply the water while hot and use the same technique you did when preparing the gold for patching - light, quick strokes. A second or third washing will do no harm and often adds to the clarity and brilliance. Repeated washings will cause laps and cloudiness to disappear. After thoroughly drying the gold, you have it now ready to be backed up.
Backing The Gold
If the layout has been made on the outside of the glass, it should be plainly visible through the gold. If a pounce pattern has been used, it can be turned over, face to the glass, and pounced with powdered charcoal right onto the gold. This is recommended for small designs, trademarks, etc. The layout is now easier to see and will enable you to do a better and more exact job. Gold should be lettered exactly as you would letter directly on the glass, the only difference being that the letters are all backward or reversed.
The backing up color, or paint, must dry very hard and firm. It must not contain oil of any kind. The slightest trace of oil in your backing-up color will penetrate the gold leaf and spoil the job. There are several good mixtures that can be used for this backing-up process. The most popular is lamp black ground in japan mixed with either gold size or quick rubbing varnish. It is highly important that backing-up colors be thinned very sparingly, as the turpentine used for this purpose has a tendency to flat the color and to render it brittle and easily chipped.
For a quick job, brushing lacquer can be used. Lacquer dries in less than ten minutes, and will give a fairly satisfactory job. Yellow lacquer is best but black or green can also be used. Quick Rubbing Varnish is a quality varnish designed to increase the vehicle content of Japan Color. When mixed with Japan Color the resultant coating is tougher and more resistant to clean up after backing up gold or to backup gold leaf applied on glass when no outline color is specified and fast clean up is desired. Clear Overcoat Varnish is the first choice for a long lasting clear coat for use over wood, metal or glass.
Reviving a traditional automotive product this material offers excellent protection from water and chemicals. It is also recommended as the final back-up coat for gold leaf applied on glass. After the shade or outline is complete Clear Overcoat provides final protection.
Silver leaf. except for a few minor changes in the finishing, is laid in exactly the same manner as gold leaf.
Method Of Procedure
The new thin, silver leaf can be laid with the same strength water size. However, this leaf must be backed-up with a heavier, non-porous backing material. For this purpose, we recommend a mixture of Chrome Yellow medium in japan. To this mixture add a small amount of Prussian Blue in japan and stir into gold size. Mixture should be thinned sparingly with turpentine to a fairly heavy consistency.
This backing-up material is chemically neutral and is considerably tougher than the mixture used for gold. Black, which contains a high content of carbon, should never be used, as the carbon tends to have a chemical reaction on the leaf and in time may cause the silver to tarnish.
Silver leaf should never be used over varnish for mat centers, as varnish also has a tendency to set up a chemical reaction that will make the leaf tarnish. In gilding mat centers on a silver job, use aluminum leaf for the centers. Instead of varnish for the centers some sign men prefer to use stale beer. To prepare beer for this purpose they allow it to stand overnight in an open pan.
Gilding is done in the usual manner, but is backed-up in outline only. These sign men then flood the centers with stale beer in the same manner as water sizing. The leaf is laid into the beer while wet. Mat centers of silver leaf laid into stale beer have been known to stand up with no signs of tarnishing for 25 years.