Saturday, February 14, 2009

Hot Glass

I mentioned before how much fun the glass is when it's hot. One surprising thing is the way the various colors react to the heat.

White glass turns clear when hot, cobalt blue transparent turns to an opaque fiery red, red glass turns black to fiery red, then back to black as it cools, and yellows turn red.

When the glass is molten, it's glossy. When it's that liquefied, it's a little too runny to manage well, so you pull it back from the flame and a sort of matte film will form on the melted surface and at that point it's a little cooler, but still melted enough to work easily. That's when you daub the glass onto the mandrel and pull off a little string of glass, wrapping as you go, and stopping when you have enough glass on your mandrel.
The the two photos of glass that's a sort of light amber transparent with the mercurochrome tip show glass which is a striking color. Striking colors are the ones where the application of heat makes the color appear. Likewise, you can over-heat the glass and make the color go away entirely. Then you can re-heat it to make the color appear again. As far as I know, the striking colors are amber which turns orange, and clear glass which turns red and another clear glass which turns bright yellow, all transparent. There's also a cranberry striking color which turns to a more ruby tone.

If you think about tempered glass and pyrex and the like, you already know there are many different types of glass. I use soft glass which melts in the 1700 degree range. The glass I generally use is Effetre formerly known as Moretti. Another soft glass is Bullseye, and people with a bench burner work in harder types of glass such as borosilicate. Borosilicate is gorgeous stuff, but requires a torch which burns hundreds of degrees hotter than mine. Different types of glass may not be combined because of their coeffecient of expansion. As the glass heats and cools, it expands and contracts. Because of their chemical makeup, these different types of glass will expand and contract at a different rate in identical conditions. Even if you brought a piece of combined types of glass back to room temperature overnight in a kiln, gradually, the piece would crack or even shatter.

I think if you click you can embiggenate the pictures.


Thud said...

ot. but I was at vinogirls today when you came up in conversation as she showed me her wish list of shoes on zapppos(?)...just what is it with shoes?

Barbara Bruederlin said...

That does look like fun. Scary fun, but fun nonetheless.

Embiggenate is my new favourite word.

phlegmfatale said...

Thud - Shoes! Shoes! Shoes! I'm not addicted. I can quit any time I want to.

Barbara - It's fun, and it's less scary than you'd think. One is VERY cautious working around such things. :) I think I got embiggenate from Tam over at the View From The Porch.

Miz Minka said...

Embigennate is a cool word. I think you should submit it to Webster's. :)

What kind of a surface or surface covering do you use when you're playing with colored glass sticks and your torch???

Robert Langham said...

Earrings were a direct hit on Valentines. Thanks for your wonderful work.
Ddidn't get to embiggenate yet, but i think that is coming up shortly.

phlegmfatale said...

Miz Minka - I can't take credit for it - I think it was Tam or Roberta X wot came up with that one.
I have a fiberglass board for the table surface. There's a name for this kind of board, but I can't for the life of me think of it. Fumes getting to me, perhaps...

Robert - I'm SO delighted, and it's exciting to be getting new pieces of my work out there. I'm honored the Redhead will be donning my earrings. Thanks for your patronage!