Glass insulators with residue

over the weekend i recovered a few glass insulators off a downed pole and noticed they had what looked like oil up inside along the threads. anyone know what this is and why?

My guess is it's creosote that's slowly "sweated" out of the treated wood insulator pins over time.

It was likely tar or creosote. There have been some made that required oil to be filled in the hollowed out skirt ridge. You have better chance of getting hit by lightning or winning the lottery than ever finding one of these. Last I heard one was located in an old junk shop in Colorado four years ago, and was auctioned off for like 20 grand.

Can you describe the color (Aqua, blue, teal, turquoise, lime green, dark green, clear, or something else) and embossing on the insulator ? I know this is tough, how about the shape ?

Most common ones are embossed "Hemingray-42", "H.G. Co.", "Brookfield", or have just a letter "B" on their skirt sides.

its a clear whitall tatum with a number 1 on it. shaped like a hemingray 42. with the sun shining on it it looks like it could be in the color of root beer. and if you flip it over and smell it it smells like old motor oil. i didnt take the pin with it.

Then it's just water moisture that has been accumulating in the rotting wooden pin while the pole has been down. You have dirt, carbon grime, & rotting wood making it look all dark.

If after thoroughly cleaning in a lye or acid bath, the glass is a light honey color (they call this "straw" or "peach" colored glass), its worth about $5. Otherwise it's just a dirty clear Whitall Tatum No. 1, which aren't even worth a buck. A W-T #1 in purple glass is about $25 bucks.

You find me one of those in Yellow-Amber (color of beer), bright green, or Orange glass... I've got several hundred bucks for ya !!

i dont plan on cleaning it out. we like the way it looks as is.