Originally Posted by Judy in MN
Another word of caution about the coffee mills (the ones with whirring blades): Keep an eye on those blades. One day I was happily whacking heated and chilled rod ends into frit and I noticed dark speckles in my frit. The blades were disintegrating! Oops!
Judy in MN
Judy, I had that problem too, but I think you were mistaken about where the real contamination was coming from. Coffee grinders are usually plastic containers with blades inside. Blenders usually have a rubber gasket at the bottom. If you want to try again I'd suggest this, which I have used to make many pounds of clear an d other color frits.
1. Buy a cheap blender with a glass container
- I'd suggest a cheap Oster, maybe $30.
2. Remove the rubber gasket from the bottom and instead put a thick bead of Glass Tack(glue) where the gasket was and in the threads. Screw on and commit yourself to vacumming out(Hepa vac, always) and wiping by hand with moist paper towel.
3. Use clear silicone rubber to glue on and seal the small opening cup most blenders have in the middle of the lid.
What you will find is that it takes several batches of frit making to even take the sharp edge off the blades and the glass container will have minimal frosting from the frit. So only microscopic contamination if any.
The plastic lid?- glass rarely or barely hits it, so it doesn't add any contamination either. I find the lowest speed works better than the higher - the higher just seems to keep the frit swirling around like stuff in a tornado.
For anyone making frit, I'd suggest a good to decent HEPA filter that is dedicated for the frit making area and that you uncap the grinder(ditto for frit pounders and pouring them out) directly in front of it. I use a "WIX" brand one - the filters are cheap enough I change them every 2 weeks or less.
For anyone using massive amounts of frit (me), I would suggest you consider saving your pennies and buying direct from Bullseye if you use COE 90. Once you get to $800 IFIRC, the discount goes to 50%. So a pound of most frits is roughly $10.50/lb. And no powder on your fine and larger frit, which leads to cloudiness in many compositions. And fewer concerns of silicosis.
And depending on types of work you are doing, you might not generate nearly enough clear glass scrap to meet your frit needs. I certainly don't.
Also for COE 90 folks, UROBOROS frit in 4 lb containers can be had for ab out $10-11/lb in their 4 lb. containers. I've had zero compatibility issues with Bullseye glass over hundreds of compositions.
I'd fully agree with the folks that suggest you buy or build a piston type frit crusher with a handle that can take getting hit with a hammer(I use a 5 lb. mini-sledgehammer) - placed on a solid surface(concrete block?) it only takes 2-3 wacks. More wacks don't get you anywhere, as the glass has then packed together and is really quite strong.
Pumping the piston up and down by hand is highly inefficient and is pumping out plumes of glass dust on every stroke like a bike pump. Silicosis sounds like it really sucks - wear a respirator no matter how you do it.
If using a blender you can stack pieces up to 2" square and set them on top of the blades, then hit the button - the pieces fly up and never jam up the blades. IF you just dump them in the blender can't start against a chunk of glass. Blenders are really not that strong.