High temperature SAND?!?

[ApprenticeMan]

Hello, I am wondering if I could heat up regular old sandbox sand safely and plausibly up to 1550F? What temperature does sand turn into glass? A customer of mine had mentioned he used a metal box filled with sand to heat treat dies and punches when he was a diemaker.

[Ice Czar]

more about glass then you ever wanted to know
(but really should read if you ever plan on heating something up and walking away, pro glass furnaces get turned off when they get rebuilt)

assuming its silca sand 1650C (+- 75) or 3002F +-

the beautiful blue tempered parts often seen in handmade watches are heat treated in a bed of sand to equally disburse the heat
not sure about the recommended granularity size, would assume the finer the better

An Introduction to Peter Speake-Marin, Independent Watchmaker
Blueing on brass
(note how its work hardened immediately before the tempering )

Watch and Clock Restoration
http://www.watchman.dsl.pipex.com/wa...20ellicott.JPG

[jimbob]

I would do it slowly to remove the moisture in the sand, and have a vent in the box/container to let the moisture out else it will explode

[sstreckfuss]

I'm just going to throw this out there because I work with Silica sand, it can cause a condition called silicosis so you should wear an appropriate respirator and definately keep it away from the kids.

The amount you are likely to use means your risk is neglible at best but I wanted to make sure it was stated.

[ApprenticeMan]

I guess is should have explained a bit what i am trying to do. Going to try and use a tube of sand inside a long forge/oven, for hardening temperature, 1550F. I figure the sand would evenly disperse the heat a bit better than just a plain tube in a tube, i'll have both the tube itself and the gasses from the forge vented out, thanks for the heads Streck on the silicosis, nasty thing that is. I hope to have a venturi effect going on all around the tube, so as much as possible no direct heat onto the tube of course. So i could use just plain old silica sand?

[ThomasPowers]

Sand was used as a forge welding flux for wrought iron so it will melt near those temps; OTOH you shouldn't be up at those temps unless you are working with high alloy steels.

[ApprenticeMan]

OK, so this is a go then. Worth trying atleast, like a salt pot setup but with sand.

[sstreckfuss]

I tried to melt silica sand at work one day just to see if i could and I could get it tacky enough to not blow around with direct propane but not melt it. It held temperature VERY well for quite a long time, I think it would work well for your application as long as it doesn't melt at your temps.

[ApprenticeMan]

I'll make up a small setup, a prototype for knife size blades and try it out.

[Mende]

Keep us posted! I am looking for a way to heat large blades uniformly without having to build huge bonfires or making a huge ground forge that would burn a truckload of coal in half an hour.

If sand works than I could build an insulated furnace with one or two big burnas for my heattreat needs