The art of decorative glass chipping with hide glue consists of the following steps:
Preparation of the glass surface.
Pouring the warm animal glue solution upon the glass surface.
Jellation and preliminary air drying of the glue film.
Oven drying of glue film and subsequent chipping of glass surface.
Finishing of the chipped glass surface.
(1) Lightly sandblast or etch the area of flat glass to be chipped (Pre-etched glass is also available).
(1a) Tape the outside edges of the sandblasted area with masking tape to create a dam or containment for the liquid glue.
(2) Measure area of glass to be chipped and convert to square inches to square feet.
(3) Prepare a one to two part glue / water solution using the Glass Chipping Glue (GCG) by soaking the one part, by weight, dry glue in two parts, by weight, clean, cold water for one hour. Then melt in jacketed containers at 135 - 145°F. Let stand at this temperature until reasonably free of air bubbles.
(4) With glass at room temperature (70 - 80°F) and the glue solution at 135-145°F., with the glass plate Perfectly Level, pour sufficient glue upon glass to deposit glue equal to three (3) ounces of dry glue per square foot of glass area [Nine (9) ounces of liquid glue as prepared.] (or less if a smaller chip pattern is desired).
(5) Let glue solution jell firmly upon plate before moving to preliminary storage for air drying.
|(6) Place plate in drying tunnel or chamber where a gentle draft of air at room temperature is blown across the glue film (70 - 80°F). Let remain until glue film becomes tough and somewhat hard. The glue film when tested with thumb nail should not cut, but should indent like hard rubber. NOTE: At this point, ratio of glue to water, in film, will be approximately one to one half.
(7) Remove to oven type drier and dry at 125°F. After four to eight hours drying, on average, the glue film will pop off chipping the surface of the glass and creating a moderately fine sized pattern. (With some glass a hot day will suffice.)
(8) Those particles of glue not popping off by themselves can be scraped off by a blunt spatula or wooden board. (Use Eye Protection)
(9) Masking tape is removed and glass washed to remove all traces of glass, glue, and masking tape.
The above outline, while relatively simple to follow, is subject to a number of variations.
To duplicate results on a production basis, particularly as to type of glass chipping pattern, it is essential that all steps of the process be under strict control.
That such steps are difficult to control is obvious, particularly as to accurate control of the dry weight of glue deposited per square foot of glass, and the ratio of glue to water, in step (6), just before glass with air dried glue firm is transferred to oven for final drying. A discussion of the controls and variables follows.
The type of glass has a bearing on the relative ease and success of chipping. A hard, flint-like glass is impossible to chip with any uniformity of chipping, unless previously sandblasted.
Some of the plate glasses will chip fairly readily without sandblasting; but sandblasting is recommended.
Decorative Glass Chipping - continued on page #2