Grit question

[raindropsroses]

I got some #36 sc and I’m not sure what it’s good for.
I have a lortone 3a and a slighter bigger one. I think it’s a 5lb barrel.

[python]

36 grit is a very coarse grit.

As I'm a newbie, take this with a grain of salt. But from my understanding, it should only be used in large tumblers with large rocks due to the extreme coarseness. Using it in barrels of 3lbs or less is just going to waste it. I'm not sure if a 5lb barrel is large enough or not.

I'm sure some of the more experienced members will have a definite answer. 👍

[chris1956]

Some time ago someone referenced a Lapidary Journal article from I think 1967.  In it they tested various grit sizes and amounts and if I recall correctly, 80 grit was determined to cause the most wear on rocks.  Coarser grit like 36 didn't seem to improve wear.   I have used 35 and 35/70 in small barrels (including a 3A) and it seems to be gone after a week (other than recently when I tried using it on small obsidian).   I am going back to using 80 grit as I couldn't tell any improvement with the coarser grit.   

[chaosdsm]

36 grit should last longer than 45/70, 60, 60/90, or 80 grit, but might (along with 45/70) be too aggressive for softer rocks. I have 5lbs of it ordered for testing in my 3lb Nat Geo & 11lb Vevor rotary tumblers, for tumbling Jasper & Agate, but will be a while to get results.

[whyofquartz]

I have tried to run 36 in a lortone 3a, it did very little. It is for like 12lb and bigger as I understand

[raindropsroses]

Thanks, that is very helpful!

[mdjunkie]

I use #36 grit in my 12lb Lortone. With Montana agates the grit is gone in 4 days. If I tumble softer rock like I get from Lake Michigan, it lasts quite a bit longer, usually 6-7 days.
I save it for the harder rocks. I did try some in a 3lb barrel and it doesn't seem to use it all up in a week, especially with the softer rocks.