Glass Chipping Hide Glue

Commercial glass cleaners and sprays work well and only general cleanliness is required at this point. A U.V. light can be used to determine the uncontaminated side of the glass if you plan on chemically applying gold (Angel Gilding) or silver (Silvering), but is not necessary if gilding by hand.
 

Applying Asphaltum:
Dry your glass well, now you may apply (roller or brush) a thin even 1st coat of "Gilder's Asphaltum Varnish" to your working side of your glass and allow to dry, usually 10-20 minutes then apply a 2nd and final thin coat of asphaltum.

After the 2nd coat when the varnish film feels dry to the touch, the glass will be ready to apply your resist or vinyl to the surface for etching. Make sure to apply resist dry, don’t use water or application fluid.

To get the glue to chip the glass you will need to etch or give the surface some tooth via sand blasting using 100 grit Aluminum Oxide works well or 120 mesh sand in which Intermediate 4 mil vinyl is strong enough or you may use sand blast mask such as Anchor’s brand, seeing that we just need to frost the glass. Once the mask is applied well, you may pounce or transfer your design(mirrored/reversed) to the working side of your glass and either Knife cut the image or for those for those with plotters transfer the mask and weed out the resist in the areas desired for chipping glass.
Sandblaster for Glue Chipped Glass, Frosted Glass and Wood Signs
Sandblaster 110 lbs Capacity for Glue Chipped Glass, Frosted Glass and Wood Signs


Sandblasting:
A light frost is all that is required, as blasting the "Gilder's Asphaltum Varnish" will disintegrate leaving frosted glass, just enough to remove the asphaltum and the shine from the glass surface. Avoid large sandblasting services which descale metal or blast wood because their pressure is too high and the abrasive size too coarse. 100 to 120 grit Silica sand is adequate if no aluminum oxide or silicon carbide is available. Make sure all asphaltum is blasted off before removing mask, After blasting, remove/blow off any dust on the surface. Do not wipe it off and avoid touching surface with your fingers as it may leave oils behind or possibly cut yourself.
 

Glue Application and Leveling:
at this point, stir your "Animal Hide Glue" and make sure there's no lumps and it’s ready to apply. The hide glue is best when between 140 and 145 degrees for 5 minutes. This lines up the protein chain to deliver the glue full strength (referred to as prepared gelatin) and have the temperature hot enough to kill bacteria and not so hot to as to crack the glass. It is important the glue remains warm in order to flow and level properly.



Place the glass panel on a level work area and remove any remaining sandblast resist mask, try not to remove the "Gilder's Asphaltum Varnish". When the Asphaltum Varnish peels off to easily with the removal of the the mask, this can indicate that the glass wasn’t clean enough during its application. If this happens you may touch up any holidays or broken lines with a brush.

Hide Glue Application Bottle
Now fill up a "Hide Glue Application Bottle" with "Hide Glue". You may want to use a glove or oven mitten if the container is to hot to hold with a bare hand. Now slightly squeeze the bottle of hide glue onto the open areas of frosted glass.

Chipped Glass "Hide Glue Bottle" for Hide Glue Application
1/8” is the desired thickness of hide glue needed . "Gilder's Asphaltum Varnish" will act as a chemical dam and repels the "Animal Hide Glue" at the line edge as a water based glue won’t mix with the Asphaltum Varnish oil base avoiding ragged edge chip along your lines. If any glue happens to overflow onto the Asphaltum Varnish areas don’t worry, as the hide glue can be easily trimmed off after it gels. If any areas look rough like sand paper after applying hide glue, add a little bit more hide glue over the top of these thinner areas.

For Small areas use Large Hypodermic Needle Tips that slip onto the bottles tip. The smaller Tips allow you to apply "Hide Glue" in small detail areas and in between small lettering. Contact Letterhead Sign Supply for availability.
 

Large areas may be poured directly onto glass and glue is spread around with a Hide Glue Roller to make sure the Hide Glue is applied evenly

Chipped Glass "Hide Glue Roller" hide glue even applications
 

After covering all chipping areas wash your Hide Glue Application Bottle, Hide Glue Roller and tips or tools with hot water.

Remaining "Animal Hide Glue" may be transferred into a can or zip-lock bag and store in a refrigerator until needed again for several months, again keep it stored away and safely from any Children and Animals, and to avoid any ingestion which could cause serious illness and or death.

Drying and clean up:
The "Hide Glue" will need to gel before trimming and glue that has gone over the edges of your lines and may be assisted with the use of a fan in order to gel rapidly.  Once glue has reached a jello-like state (gelled), you may cut off any excess hide glue beyond the lines or image using a"" or razor blade.

Chipped Glass "Hide Glue Knife" excess Hide Glue removal signs tool


If any "Gilder's Asphaltum Varnish" is removed when removing excess hide glue you will not have to worry or touch up at this point.

Now wait for the hide glue to harden. Folks in a dry climates will have the "Animal Hide Glue" dry on its own and the chipping process will occur on it’s own. Folks in humid areas over 50% humidity need to assist the hide glue in drying properly by building a glue chipping box made of dry raw wood which assists in drawing out the moisture to assist the chip process. See sample of Glue chipping box (See Diagram at bottom of article).

The best humidity condition for Glass Chipping with "Hide Glue" is at 35% and lower, but ranges from 35%-50% will work fine but will be slower. Local hardware stores often carry humidity gauges in which you can gauge your conditions.

As the chipping process is under way, shards of glass can and will fly up and off so always wear the proper safety glasses to avoid glass from getting into your eyes.

You may assist stubborn areas that have chipped after a majority of the area has chipped by using a sharp X-acto knife to tap at unchipped areas.

Once Hide glue chipping is completed, you may soak the glass in water to soften and remove any remaining hide glue. Once all of the excess hide glue is removed any remaining "Gilder's Asphaltum Varnish" can be removed with mineral spirits or a similar paint thinner such as naphtha, then was the glass clean with soap and water and then to dry.

Additional Tips:
Chipped Glass looks best when Water Gilded, or left raw, furthermore painted chipped glass tends to not be visible.