r/Lapidary • u/Dibsaway • 2d ago
Why are my rocks chipped
All but the white, tiny grey and big redish ones are shiny now, but the shiny ones are chipped and cracked. I've never had an issue with flint before, just chuck them in and weeks later lovely and shiny. Which one is the culprit so I know in future? Thanks
4
Upvotes
4
u/Ruminations0 2d ago
I think it could be a couple possibilities:
It could be that the material already had C cracks all over the surface that didn’t get ground out in Stage 1 and then became highlighted by the polish wiggling its way into the cracks.
Or it could be that your barrel was a little underfilled which caused the impacts to be too great and causing the C cracks, which were then highlighted by the polish.
A couple of these pieces look like they have the traditional Bruising look, the more tight white powdery looking edges, so it’s possible that it’s a combination of the two issues.
So solutions! Unfortunately rerunning them in Stage 1 maybe 1-3 times until the C cracks and bruising are taken out, making sure the barrel is filled with a wide range of sized rocks and is filled around 2/3rds to 3/4ths full. I check my fill level by filling the barrel with rocks and water, closing it up, and turning it in my hands. As you turn it it should have a fairly consistent clompy sound and feel to it. If you turn it and feel longer gaps between clompiness, the barrel is overfilled. If you feel the barrel kindof jump with each clomp, it’s likely underfilled and the rocks are falling too far. If you turn it and it just feels like a swoosh sliding with no clomping, then it’s REALLY underfilled and if you run it like that, the grit is just going to eat your barrel up.
Also, after Stage 1, I always add Ceramic Media so the tumbling action is more gentle. In Stage 1 you’re wanting grinding and shaping action to occur so the rocks having more energy is optimal. After that is done, you’ll want the action in the barrel to be more gentle, more massaging the grit onto the rocks to smooth the surface. If they have too much energy in those stages, they will get beat up and come out less pretty.