When it comes to belt use and coldworking there are a surprising number of options out there for working your glass. While it can be overwhelming and seem a bit daunting it can be rather easily broken down in various categories.
For basic grinding and removal of material from you glass pieces we will, most often, suggest sticking with silicon carbide belts.
These belts are inexpensive and do an excellent job of working surfaces on your glass. They are easy to use and can move from rough stock removal all the way to a fine surface prep for pre-polishing.
The drawback to a silicon carbide belt is in its short life and quick change in grinding surface. Silicon carbide belts start out rather aggressive, but then quickly move a a medium grinding rate and then taper off to a very fine grinding surface. The movement between these stages can go rather quickly if you’re working a larger number of pieces or larger surface areas but can be less noticable if you are working only seldomly on your belt sander. This can make it difficult sometimes to gauge what type of surface you’ll get in your glass from each use of a belt.
Plated diamond belts, on the other hand, start out with a certain grinding surface and removal rate on your glass and stay that way for the majority of the belt’s life, which can be very very long. Plated diamond belts last 10 times or more longer than a typical silicon carbide belt in the same grit, but they will also cost almost 10 times as much. While consistency on the surface of you glass is a fantastic thing to have, up front costs on plated diamond belts can be a hiderance. We recommend using plated diamond belts only if you work a lot of material on your belt sander and find that you are replacing silicon carbide belts fairly often. The diamond belt will last longer, give more consistent results and be a better return on investment. One more thing to be aware of with plated diamond belts is that they will be more aggressive on the glass in the same grit as a silicon carbide belt. An 800 grit plated diamond belt leaves a surface on the glass more comparable to a 320 or 400 grit silicon carbide belt.
So what do you do with these rougher surfaces on your glass from an 800 grit diamond or even a 600 grit silicon carbide? They are both still too rough to polish from, so what’s the next best step?
Again, if you work on seldomly on a belt sander, the next best step is to move to a cork belt. These shredded cork belts with no embedded abrasive of their own can actually give an amazingly nice pre-polish finish on your glass from a 400 or 600 grit silicon carbide belt. Just like silicon carbide belts though they will not last as long ans wear more quickly than a diamond or Trizact belt.
“Wait a minute,” you say, “What the heck is a Triact belt?”
Trizact belts are manufactured by 3M and are meant to do fine finish work on many different surfaces from metal, to ceramic, to glass. The basic structure is taking a soft abrasive like aluminum oxide and embed it into a microscopic pyramid structure on the surface of the belt. The pyramid struture allows for more abrasive to be held on the surface of the belt so the belt gives a longer, more consistent grind on the surface of the glass like a plated diamond belt, but with a much softer abrasive that breaks down faster and leaves a much finer surface on the glass. Trizact belts are perfect for pre-polish finishes after silicon carbide or plated diamond belts are are avaialble only in finer grits like 400, 700, and 1200 grit.
But what about diamond pre-polishing?
Diamonds can also be used for pre-polishing stages with belts as well. The standard resin diamond smoothing belts allow for a long term consistent grind on the glass after plated diamond belts and give a velvety clean finish on the glass that can easily be polished from. Just like resin diamond disks though, the resin diamond belts will last only a portion of the time that a plated diamond belt will.
3M also manufactures a diamond belt that is adhered to a film backing instead of electroplated. These belts are electrostatically charged while the adhesive cures so the diamonds “stand up” on the surface of the belt. Just like resin diamond belts, these electrostatic diamond belts allow the diamond to “move” on the surface of the belt while you grind allowing for a smoother, finer surface grind on the glass. These belts are excellent for working small precise surface as they go from a 120 grit all the way to a 1200 grit. While the 120 grit will not do substantial removal of glass like a 120 grit electroplated diamond belt, it will easily shape smaller items like cabachons or jewelry pieces.
The great thing about working with abrasive belts is that there is no “one” perfect routine for everyone. Each style belt can be mixed and matched. You can use a 70 grit diamond belt for your rough grind, move to a 120 and 220 grit silicon carbide belt for your cleanup and then move to a 400 and 700 grit Trizact belt for your pre-polish step.
You can pick and choose from all different styles to fit the process that work best for your glass. Just knowing what each belt style will accomplish for you goes a long way towards choosing a routine that works best for you.
As always, we are available for any and all questions on your process.