The Breakroom > The Water Cooler


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Ade, I read that some fancy adjustable commercial ones have a center pivot in a magnet.

Seems like a doable mini-project.

So glad its not just me  :lol: but talking of furnaces I wanted to cast a part for a new project and dragged Lil Red out only to find that the insides had crumbled so that is going to need to be sorted before I can do any casting again  :doh:

What kind of lining, Dwayne?

Today I got my cerroblanket glued into the iron melter with sodium silicate. I also got a first coat of ITC 100HT ceramic coating on the face, and arranged an old incandescent lightbulb in it to keep it warm while it dried. It lives outside. Today temps were unusually warm -- we hit 40, and that was why I hurried to do the lining. It looks like the coating dried by this evening.

I don't know if this is really going to work out. The coating seems nothing like ironman's zircon stuff. More like very thinned out Portland cement -- kinda gritty and as thin as cream. It absorbed immediately into the blanket, and it looks a rough job. But  I hope it will look better with the second coat, and maybe once it's fired it will fuse into a strong coating.

The other small furnace will need some Plaster of Paris and sand mix to restore to usefulness. It's melted aluminum, zinc alloys, and brass with no problem, on propane.

I can't remember the exact mix I used now but it was perlite, sand and cement. I got the mix while looking on the net and to be honest I didnt think much of it when it was new while it insulated enough for you to put your hand on the outside it was still quite hot but the main problem was that it wasn't electrically insulated very well so it would trip the RCD with the earth on.
I will invest in some bricks or maybe a proper mix this time, have not decided yet.

Portland cement is not a good melting furnace lining for a number of reasons. It isn't very temp resistant, breaks down, and as you say it isn't very insulative.

For an inexpensive home brew lining for temperatures up to occasional brass melting, plaster of Paris and sand mix is much better. It's fine for zinc and aluminum temps. And I have occasionally poured brass with it -- maybe a half dozen pours. That's with an inch and a half lining thickness. The outside of the furnace barely heats up with zinc and aluminum. Brass takes longer and the furnace heats some eventually on the outside.

Plaster of Paris is insulative -- ever notice how light it is after cure? That's air spaces in the the hardened material. It's actually used in commercial iron works as insulative sleeves for pouring funnels. Keeps the iron hot.

It isn't high temp resistant enough for an iron furnace lining, though. But for lesser metal temps it works find with sand.

If you're going to pour frequent brass, bronze, or you want to pour iron, you'll want to go to a specialized pourable refractory or ironman's ceramic blanket and hi temp coating combo. Neither is cheap. Pourable refractory heats up slower and uses more fuel. The main problem with Ironman's lining is finding the high temp coating. His exact type seems only available in Australia.


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