I lined my wooden blast cabinet with a doubled-up layer of heavy poly sheeting stapled in place. It seems to work fine. I also put a layer of clingwrap on the inside of the glass window. Even that little bit seems to help protect the glass.

I tried some walnut shell in a pressure pot a few days ago. The tips that came with that pot are all too small and clog immediately so I just used the ball-valve on the end of the hose without them. That means that it dumps out the shell (and the pressure) very quickly. The inside of the cabinet disappears into a thick brown fog of shell dust so I had to try and feel for the pressure of the blast stream while I held the part in my hand.

It worked, but it isn't exactly optimal. Plus, my "Chargeforce" compressor isn't a real 5hp unit.

I was hoping the shell would give me a "clean and original surface" on motorcycle engine castings, but it still looks "blasted", though not as much as with the nickel slag I used for a long time.

I have some very fine garnet that I have yet to try. I suspect that will also be more abrasive than I want.

cheers,
Michael