Septarian nodule for coaster? (more good stuff)

Especially when lit from below, right James?

Great finds! I'd think the septarian would hold up OK as long as you didn't spill acidic drinks on it. I guess you could use krylon or some other sealer to waterproof the slab if you so desired. Obsidian would make a crappy hammerstone. As you've said, just to brittle. Amerinds round here used a lot of quartzite type rocks for that as it is pretty tough. Your example sure has the look of Davis Creek to me as lots of the obsidian from there is in that roughened nodule form and mahogany is common in he area.....Mel

Wife beater rock is probably what he was thinking. Okay, maybe not.

I think you have the front and back mixed up on the septigenarian.
Jim

Nice finds! I think we need to come down and visit your swap meet. I think Mel's got it, some clear coat to protect the rock and you've got a real neat coaster.

Russ

I never had much luck with any spray on or brush on coatings. I have went been using pour on finishes like bar top coating. I just did 3 this weeks but have not taken pictures yet.

Here's some I did in the fall.
forum.rocktumblinghobby.com/thread/61681/coasters-poured-on-epoxy-finish

I use these at my house and the only issue I have found is that sometimes the sweat from a drink will cause a suction and when you lift your glass the slab will lift with it.

Chuck

Thanks, Russ and Pat! I've not coasted any rocks yet, in fact, I always thought it was cheating when someone would spray a slab to make it shiny, instead of polishing it. I still have slabs picked up at shows that need to be worked and have this removed.

Russ, I've picked up some pretty cool stuff at the swap meet, but it is very hit and miss. I actually live just a few blocks, walking distance, from the Spring Valley Swap Meet, but we don't go there very often. The type of people that go there are very rude and pushy. (I'll not stereotype here.) We usually drive out to Santee Swap Meet, about twelve miles away. Some weeks I don't see more than one or two rocks, other times I score!

Chuck, I also wondered about the suction between a wet glass and smooth surface, either polished or coated. Not a good thing to have the coaster lift up with the glass, then drop to the floor and possibly break. Or drop back onto glass-topped coffee table. I've got some standard size round coasters made with sandstone. Very porous, so absorbs the water. Glass doesn't stick to coaster, and condensation doesn't pool on top.

James, I like the thicker 3/8" thick septarian slab for a coaster as well. The other coasters I have are more like 1/4 inch thick. Only problem is, heavier makes a better projectile .  But now, I'll have to be on the lookout for more of them, around the same size.  This one was a one-off.

Yes , thicker is better. A friend put down his glass on a regular slab. Broke in two. Two coasters!

I'm in the process of making coasters out of thicker serpentine slabs. Double length --- space for the coffee and the cookie.

Oh come on Pat. You give people "ONE" cookie. Who eats one cookie? I would have to drill a hole, insert 10 inch dowel and buy cookies with holes in the middle so I can stack them up. Or a stone bowl with a flat spot on the edge for the drink.

I am waiting for someone to say "put a sheet of cork on the top". lol I actually have some slabs of wampidy sunrise that are big enough to put a cup size circle of cork on them and they would hardly be noticed.
Jim

Blood grooves in a bayonet Pat. Makes it easier to pull it out of the body.