Saturday, April 21, 2012

I'm Melting....

These are silicone carbide shelves. Q) Are they supposed to melt like that?

Well. I thought the answer was a resounding NO, but it turns out that ceramic-bonded silicon carbide is less impervious to the aggressive fluxing action of the soda, and can suffer from "progressive grain boundary corrosion." Son of a bit.

These were bought used, for short money, along with some others that are holding up like champs - those must be nitrite-bonded.

I can't afford new shelves right now, so my option is to grind the living shirt out of these, and the - reluctantly, because I am well aware of the pitfalls - apply a thin coat of kiln wash to the undersides as well as the top. Oh, what a world, what a world.

2 comments:

shane mickey said...

well i wouldnt go putting wash on the underside. here is what will happen. the shelf is impregnated with the soda, it will push from underneath probably causing the wash to flake. worse case the soda will flux the wash and the two will drip. best way to get rid of some of that drip is to scrap it off really well, then wire brush the crap out of it. Then wipe with a thick damp sponge. if possible fire them in a residual firing (no soda)then repeat the steps again. the wire brush will help get into the crevasses and remove the soda. do not flip them, i made that mistake, big black foamy mess

Lori Watts said...

Thank you, Shane! You may have saved me from yet ANOTHER learning experience.

I've ground the hell out of the offending shelves, sponged them off, and used them in a bisque. I will now get a wire brush and start again.

Once again, thanks. L