View Full Version : color at bottom of pot

Mark Dolan
01-04-2012, 10:18 AM
Having just shut down my furnace for the first time, I noticed a swirl of color at the bottom of the pot this morning (see attached pic). It must have gotten there when I used a blow pipe to gather out the last 1/2 inch of glass out of the pot. Any ideas on how to extract that color so it doesn't mix with the clear when I fire up next?

Also, if you look at the attached pic, there is a 1/2 inch gap between the rim of my pot and the baffle. I remember reading somewhere in this forum that it's a good idea to close that gap with fiberfrax or Ceramic fiber to protect the elements from gases bled off during melting. Did i read that right? I'm a little concerned about stuffing it will a material and then having that material flake off onto an element. It might be one of those trade offs though, where protecting against gases is more beneficial than the occasional flake of fiberfrax landing on an element.

Scott Novota
01-04-2012, 10:26 AM
Edit: You, not I, will never notice that once you fill the pot back up it will just mix in. I would not worry about it at all.

Also, seal off the chamber between the pot and the elements. Cut some brick to size to lift that pot off the bottom of the furnace and get it about 1/4 of and inch from your baffle ring that is on top of the pot.

Then take some fiber frax and cut a ring to sit on top of the crucible between baffle and the pot.

This will seal off the off gas of those nuggets and keep it off your elements. It will double your element life at a minimum.

Randy Kaltenbach
01-04-2012, 12:13 PM
You may benefit from the posts of Richard Huntrods regarding his use of rammable around the pot rim.

Pete VanderLaan
01-04-2012, 02:50 PM
That color will not influence your clear at all.

Richard Huntrods
01-04-2012, 09:22 PM
I think you should raise the pot up so it's level or almost level with the top of that opening. Then ram dampish frax into the gap to seal it.

Yea, glass drips will mess with the frax gasket work over time. It should come off easily during downtime maintenance.

It's still better to seal the elements from the vapors than not do do that.


Mark Dolan
01-05-2012, 10:33 AM
Thanks Richard. When you say "dampish frax", I assume you mean the mix version? I have some ceramic fiber blanket in the shop but it sounds like you are using the mix version of Frax for a complete seal.

Richard Huntrods
01-05-2012, 11:06 AM
By 'dampish frax' I mean regular fibrefrax that has been wetted with water and then had most of the water squeezed out. That way it packs in firmer.


Pete VanderLaan
01-05-2012, 11:13 AM
You can also get Lubed frax which has I believe a lanolin base which allows to to be tamped as well. It has the advantage of not being water which can create issues in furnaces while boiling and turning to steam.

I got Charlie Correll to try it on our last moly furnace and he's a total convert. No dust, easy to ram.

Michael Mortara
01-05-2012, 12:56 PM
Then again system 96 in an enclosed electric environment full of soft refractories has its own issues...

Lawrence Ruskin
01-08-2012, 12:28 PM
you can also use sodium silicate to dampen the frax,

it will set and keep the fibers from flying around.

Sodium silicate is sold by refractory companies and is called rigidizer.

No jokes here please...

Locally Inproheat has it.

Rollin Karg
01-08-2012, 01:06 PM
you can also use sodium silicate to dampen the frax,

Sodium silicate is sold by refractory companies and is called rigidizer.

I'll buy colloidal silica as a rigidizer, but not Sodium Silicate. The Soda will melt your Frax.

Lawrence Ruskin
01-08-2012, 01:09 PM
i think they are tha same thing...

Pete VanderLaan
01-08-2012, 04:08 PM
Rollin is correct. Sodium silicate is 50 % sodium. Rigidizer is either colloidal silica or colloidal alumina. No soda in it. Colloidal silica plus milled zircon is ceramic shell.

As the man said ,water glass , it melts things.
It doesn't even work as a rigidizer at useful temperatures. But it's great for storing eggs. ( Ick...)