I just finished making a small manual crusher for making small quantities of my own frit. Being my 2nd attempt, there are a couple of innovations I thought I would share that are not so obvious to newcomers.

Metal contamination was the biggest shortcoming of my 1st device. I actually used stainless steel, but glass being as abrasive as it is removed enough metal to cause noticeable brown murkiness especially in light colors or clear. I couldn't think of a way to remove the metal contamination or avoid it. A little research led me to the idea of using a MAGNET! however that would require using magnetic steel for the crusher and my stainless steel was not (some is). That meant starting from scratch.

This unit is made from 50NB outer with 40NB inner mild steel pipe. Neodymium magnets will be used to pull out metal contamination from the frit after it is ground. Rust of course is going to be a problem now. It was cleaned by pickling in HCl so that it was spotless but in the time it took to wash the HCl off at the tap and walk back to the shed already a very thin layer of rust had begun to form. Before I use it with glass I will toss some clean dry sand and give it a good pounding order to abrade away any surface rust then give it a good blow out with the compressor. Sandblasting would be a convenient way of preparing the metal if one had access to that.

Creation of glass dust is a bit of a problem when making frit. It has a tendency to blow out of the crusher with each down-stroke of the plunger. That is why this unit has been left open at the top, and the plunger is not solid or closed at the bottom. The idea is to minimize the amount of airflow as the unit is operated.



I will store this in a plastic bag with some desiccant to keep it rust free in between uses. Magnetic stainless steel would be the ultimate way to go. Maybe for Mach 3!