Found this broken piece in the creek bank. Southwest Pennsylvania. Farmhouse was built in 1922. Coalmining country.
Would have been about 18" in diameter. There is a rough coating in the glaze on the inside and outside of the bowl section. Abrasive enough that I figure it served a mechanical purpose. There are three grooves on the rim that aren’t symmetrical to each other.
There might be a makers mark in the center of the glaze inside but I can’t make it out. There is also a light blue/green stain on the bottom that might be a mark.
Any ideas?
probably one of those ceramic power insulators
I’m starting to think it is part of an insulator. It’s just so big to be one. It’s almost double the size of the the vintage 1950s one above. Maybe one section of a huge high voltage assembly?
I do know that mines and other things would often bring their own electrical generators and systems and lots of PA has a history of coal and other mining. Someone knowledgeable in that sort of history might be able to confirm/deny that theory.
Looks like it to me, albeit a bit large …
It’s absolutely huge if it’s an insulator.
Looks kind of like a lid for a fermentation crock?
History of gold mining in the area? Might be a pan for panning gold. Lots of nooks and crannies to trap gold particles. Rough centre surface for breaking up chunks with a finger. It’s not a design I’ve seen before though.
crock-Pot or a bowl probably
The surface is too rough for use with food. It’s like small gravel or big sand at the surface.
It “could” be a sewer/pipe cap but your geographic location and time period suggests it probably isn’t. I’ve seen reasonably similar items that serve this purpose.
The rough (frit) glaze surface would be the opposite of what you want in a HV bushing, because they would wick and store conductive water.
Interestingly it’s on the both the top and the bottom. Perhaps this high surface area makes it more compatible with some specific glues; allowing you to stack a pile of these pieces together to make a full bushing? That might also explain why there is not hole in the middle, this could be a compression style bushing stack for holding wires up in the air off a surface.
I don’t know enough about high voltage to speak with any authority, but that totally sounds reasonable.
As for construction of original insulator, that’s what I’ve decided as well. It’s a stacked assembly. There are smaller versions.
It’s a really big insulator and very possibly could have been used for mining power supply. There are mines within a 1/4 mile.