Stamp casting issues

[JRay8]

Help! I cast a stamp blank and ran into two problems. First the water from the wet sanding for the the blank got the stamps wet and turned the edge dark. It was exposed from where I squared the blank. How do you protect that edge?next after finishing the blank it had what looked a sctratch so I put it back on the lathe and wet sanded it more. No matter how much I sanded the blank down the scratch looked exactly the same! Has anyone had that happen with pr before? Almost like it was a defect in the casting.

 

[1080Wayne]

Thin CA is usually the best way to protect the edge . Re scratch - You didn`t by chance cast a hair into the blank ??

 

[JohnU]

I coat my stamps with thin ca prior to casting to help with these issues. After trimming the edge, treat it to some thin CA. As for the scratch, it sounds like its not on the surface if it didn't change from sanding. Possibly a crack inside near the stamp or tube?

 

[PTsideshow]

I know from past castings of items, that threads and hairs form yourself and any pets can get into the pour. Try looking at it straight on from the side of the blank you my be able to see it.
:clown:

 

[bruce119]

I coat my stamps with thin ca prior to casting to help with these issues. After trimming the edge, treat it to some thin CA. As for the scratch, it sounds like its not on the surface if it didn't change from sanding. Possibly a crack inside near the stamp or tube?

That's pretty much how I would do it. Glue the stamps to the tube then put on the lathe give 2 or 3 coats of med. or thick CA. let cure then cast. After squaring the ends put a puddle of thin CA on a piece of plastic dip the ends to seal them then turn to size. Paper is like a sponge it will soak up water & P.R. and get that dark transparent wet look. As for the crack maybe you used to much MEKP and it cured too fast. Don't use what the instructions say. Use only 3-4 drops per once. If your cast cured in an hour or 2 you got way too much MEKP you will get too much heat leading to cracking, shrinking and your finished blank will be very brittle.

Good Luck have fun
Bruce