Melting glass

[slowworm]

Has anyone tried melting glass bottles? Not bushcraft related but some people have had a go at melting metal and I wondered if you could melt glass bottles down into a block of glass without having to spend a fortune on a large kiln.

Could this be done with a home made clay pit, charcoal and bellows or would I not be able to get the temperature hot enough?

 

[TLM]

With bellows easily.

 

[Tony]

yeah, if you get a fire hit enough it will melt glass, we've done it around campfires before so you should be able to do it..

 

[bobnewboy]

[sorry, I have no idea why this is all in italics. Can’t seem to fix it either...]

My missus has an Etsy shop for art glass - stained, leaded and fused. She sells slumped bottles as cheese/snack trays as one of her products. The bottles usually need around 800 centigrade to melt, and then to be slowly cooled over quite a long period - several hours - to avoid internal stresses that would just shatter the result. If you can get a fire to a suitable temperature, for long enough, you would get a puddle of molten glass, but beware any kind of rapid-ish cooling.

 

[TLM]

Yes, apparently rapidly cooled large glass objects can shatter almost explosively.

 

[Nice65]

Yes, apparently rapidly cooled large glass objects can shatter almost explosively.

Google Prince Rupert Drops. They’re glass drops rapidly cooled so huge tensions are trapped in the glass. They explode dramatically if the tail of the drop is broken.

 

[slowworm]

My missus has an Etsy shop for art glass

I've seen the slumped bottles and quite like them.

I'm more thinking about converting a dozen or so scrap bottles into a large lump of glass. It doesn't have to be cast or pure so I was thinking of getting a fire up to temp and allowing the bottles to melt into a hole at the bottom, then cool gradually.

I've accidentally melted small amounts of glass, aluminium etc in a large bonfire but want to try something a bit more controlled.

 

[Mesquite]

I'm more thinking about converting a dozen or so scrap bottles into a large lump of glass. It doesn't have to be cast or pure so I was thinking of getting a fire up to temp and allowing the bottles to melt into a hole at the bottom, then cool gradually.

You may find that's very difficult to do as glass isn't all the same and have different contraction and expansion rates. Because of that you might end up with it cracking and at worst exploding apart as it cools.

It might be possible to stop that happening by melting the glass into a container and thoroughly mixing it all together together so it's one homogenous mass and the stresses will spread evenly throughout as it cools

 

[RG30something]

We've melted glass in a campfire before. We just used a normal campfire and a hand pump used for blowing up inflatable beds and we were able to melt glass bottles pretty easily.