I'm wondering if anyone has some good advice on how to tumble labradorite. I had a couple odd pieces in mixed batches from the Rock Shed, and they always looked good through stage 2 120/220, but then started looking worse in pre-polishing stage.
At this point I figured out what material I was working with, started learning about the Mohs scale, and decided to try tumbling a batch of labradorite on its own. As a newbie, maybe this was a bit ambitious, but nonetheless, here I am...So again, things are looking good through my grinding with 120/220, but I would appreciate any tips for pre-polising and polishing stages. I'd hate to ruin the batch at this point.
Should I tumble with an extra step of AO 1000 before polishing? Would a dry polishing be better than wet polishing? Any advice is much appreciated. I'm working with a Lortone 33B.
Post by charles kuchar on Mar 11, 2012 18:07:26 GMT -5
peachfront just sent me a piece of labadorite. it has three sawed edges, all square to each other. only one has any hint of blue. there are a couple of irregular places that have the blue though small. i am taking it to the rock club for the next meeting and finding out how to slice it for the best show. then i would try to polish with something llike a genie or something like that. charlie
Post by 150FromFundy on Mar 13, 2012 10:49:25 GMT -5
I have had little success in tumbling this material. The "labradorescence" effect is only visibly in one plane. If your rough happens to be oriented correctly, you will get some of the effect in small patches on your stone. To maximize the effect, you have to find the correct plane, cut the material accordingly, and grind/polish along that plane. This works well for clever cabbers, but not so well in a tumbler.
God of Multiple Parallel Universes Full of Rocks and Apprentice to THE ONE.
I've tumbled moonstone which is very similar. My advice is to start with your surfaces as smooth as possible so that the grit is less likely to get into cracks and crevices and make them into canyons. Using a wet saw, you can cut the sides and put your scraps into the tumbler as well. Adding rough which is softer and/or lots of plastic pellets for cushion helps.
I had some luck adding a couple slivers of Dove soap to the tumble. It slows down the action, but helps to buffer. More cushion in 500 and polish is advised because the slurry is thinner in those stages.
I'd try more cushion before trying to add an extra step of 1000. Good luck! Jo
Hey Charlie, this is off topic but related to your comment on labradorite sawing orientation.
I don't remember where I picked this up but when sawing chatoyant things like lab, spectrolite, tigers eye etc you can use a bowl of water (or thinned paint as it was presented to me). Hold the stone over the bowl and position yourself looking directly down at your stone between you and the water. When you get it oriented that you see with your eyes the best way to hold it for the best flash, lower the stone straight down into the liquid. It marks a straight level line on the stone that you can use to orient it in your vise.
It's worked well for me... There's advantages and disadvantages to using paint vs water, but an aluminum stick to mark the waterline has been good enough for me.
Post by charles kuchar on Mar 13, 2012 18:10:23 GMT -5
thanks for that tip... the 6" saw i bought from lynn was shipped today. and ordered some oil to use in my saws now. the old timers insist that oil is so much better. ok, i will try it... thanks. i will mention that tip at the next club meeting. charlie
Just to report back, the tumbled labradorite experiment was a bust. It probably looked the best after stage 3, but the polishing stage was a disaster, with lots of pits, grooves and cracks developing. I put this aside a few weeks ago and haven't been able to look at it since. Back to jaspers and agates and other more tumbler-friendly material.
Some day when I have more tumbler capacity, I'll give it another try, but right now I'll focus on higher percentage wins. Next time I'll take pictures too. It's all a learning experience.