Articles by Rick Glawson
Glue Chip - Standard Method / Glue Chip - Rawson Evans Method / Glass Silvering / Angel Gilding Process / Lead Nitrate Deposition / Hydroflouric Acid/Mica Glass Embossing Process / Guide to Laying Abalone / Material Safety Data Sheet for Hydroflouric Acid
GLUE CHIP PROCESS - RAWSON AND EVANS
Using a clear piece of glass, determine the "clear side" of the glass, and give an even coat of asphaltum varnish over the entire surface. Let the varnish dry (approx. 10 minutes). Place the stencil material over the asphaltum varnish. Cut and remove the positive image to glue chip, sandblast lightly through the asphaltum varnish, lightly frosting the glass. Remove the stencil off the asphaltum, leaving an asphaltum-coated panel with a sandblasted image. The asphaltum varnish will repel the glue when flowed into the sandblasted areas. Note that in production, a metal stencil can be used in place of the vinyl resist for sandblasting.
The glue mixture should have twice the amount of water than usual and placed in a plastic squeeze bottle. [For the greater portion of glue chip work, use a water to glue ratio of 1 ½ to 1. Use one 3 oz. Dixie cup full of glue & 1 ½ 3 oz. Dixie cups of water per square foot of area to be chipped. When soaked and heated, this ratio will allow the sufficient flowing out of the glue before it gels. For vertical brush application use 1 to 1 and for large horizontal areas increase the water to as much as 2 to 1. This allows the glue to self-level evenly on the panel. Once it gels, carefully roll the tenderizer over the surface giving the appearance of perforated meat. This generates multiple weak spots in the glue film aiding in pattern consistency. Generally, this method is only used on areas of 6" square or larger.] The size of the nozzle opening will determine glue flow. Level the glass and squeeze the glue onto the blasted area allowing the glue to flow to the image perimeter. It will seek its own level. A very thin-stroked design will need the viscous glue squeezed enough to puddle so that when viewed from the side, it has a raised effect. Any glue that flows over onto the asphaltum will cause no concern, as the asphaltum will pull off the clear glass. If the glue bridges between two blasted areas, a surface tension is created and over-chipping will occur. These bridges need to be trimmed away after the glue gels.
Then proceed as normal for drying and chipping. This
process eliminates the re-cutting of the glue. If a double chip is desired,
re-squeeze a second coat of glue after the first has chipped off. Also,
after chipping, if an undesired area of sandblasting remains in the image,
paint asphaltum around the area (also paint asphaltum on any small chips
to avoid double chipping) and squeeze your glue in that area. Let the
glue dry and chip. This technique will camouflage the error, and the correction
will be undetectable. For drying, a small hair dryer on a low setting
works well. After chipping, soak with water to remove any bits of remaining
glue. Then remove the asphaltum with mineral spirits.