Tempering Glass

It's supposed to be good to 1,472F. Hope I don't get to 1,473F

One reason I cut it in half was so I could Jason it up and still have a piece left. I am going to try to not pour over 1,400F just for grins.

I hadn't thought about aluminum sticking to it. It doesn't stick to the glass where it has solidified. I sure hope it doesn't stick to the Pyroceram. I guess if it does get out the torch.

Got to make new flasks for it.

 

Looking forward to seeing this!!

 

Jason had it right

The Pyroceram did not break but the aluminum stuck to it. Then as the aluminum cooled the Pyroceram spalled chunks off, possibly the aluminum pulling it as it shrank.



I'll try Jason's suggestion of pulling my next one off hot to see if the glass will come off unbroken, and if not, it's back to the old flying tempered glass. And I have renewed incentive to temper glass. Here's the video if you're interested.

 

It's interesting that the aluminium stuck to it so well, not sure what you could coat it with to help: soot from a candle flame maybe?.

 

It needs to be see through, I've thought about a light dusting of parting compound and just put up with the haze.

 

You might also try (obviously don’t know if it will work) silicone spray. No visual impairment and resists adhesion of almost all “glues.”

Denis

 

Hmmm, I think silicone may crate carbon at temperature. Might work.

 

If I had to bet, I’d bet against it. I think you are right about thermal degradation preventing silicone from being effective.

Denis

 

I just don't believe it. Actually I have some plexiglass I bought specifically to make some visible flasks for colored water pour. Even though they have similar viscosities they have different densities and surface tension. Those all come into play for nearly open channel flow, in sizes near the meniscus dimension. If we were looking at 2" runners I'd have a lot more confidence. When I saw the glass pour on The Home Foundry I abandoned the plexiglass for now.

My first job was with the Tennessee Valley Authority. They designed a fancy curved spillway in the 1960's using scale models, which they were really into for channel design (I was in the nuclear power part, didn't have a dam job). The spillway was curved as it fell and they used their vast modeling skills to bank the curve so the water would flow evenly across the whole spillway. It was built. Years later it was needed. All the flow was on the inside of the banked curve. The model was inaccurate. I remember that these few years later.

Since I can actually look at metal flowing, even though it is chilled by the glass, I have much more confidence in it. It is also much faster to model in sand rather than cutting and gluing plexiglass together. I still intend to make at least one plexiglass model when I am settled on what I want to use to see how water performs. Not sure how I'll model a foam plug however...

I have no desire for the dramatic explosion of glass, it still makes me jump even when expecting it and I'm usually not too goosey

Not necessarily. If it's making carbon only after the flow hits it then the metal may not stick. It might affect the fluid dynamics, of course.

 

I'd initially thought you could use an "Aquadag" suspension of graphite in water to get a transparent coating of graphite on the glass. Then it occurred to me that a light, fairly transparent dusting of soot would still let the aluminium still be visible and it would be a lot easier to get hold of a candle.