devitrification

[jocko]

When I was at OSU many years ago I polished chunks of crystal and pieces of blown glass. Once I got past the cork wheel to the felt wheel I was told the reason the felt step got that shinny finish was the wheel along with the cerium heated up the surface, I’m guessing like a fire polish. So before I go to the expense of the cork and felt wheels will that remove or reintroduce the film back into a nice shinny piece of glass?

Thank for your time

Mike

[wordana]

You will need to remove the devit completely or coat the piece with a layer of powdered frit or with a devit agent (do a google search —  you will find products such as spray-a, superspray, and a do-it-yourself solution made of borax). Just firing polishing without treating the surface will likely just cause the devit to spread.

Dana W.

Jester’s Baubles Fused Glass Designs

http://www.jestersbaubles.com

[Stephen Richard]

Unless the piece is flat, fire polishing, even to a matt finish will probably distort the piece as fire polishing occurs at ca. 740C and over.

Stephen Richard

blogs at: http://www.verrier-glass.blogspot.com/ and  http://www.glasstips.blogspot.com/

[Jolinda]

Dana,

Thanks so much for that reminder!  I was just cruizing through the posts here, and even after fusing for many years now had a piece ready to refire after sandblasting off the devit…and sure enough it was about to go in without the Spray A …except for your good reminder.

Funny how things happen like that.

Happy Day!

Jolinda

 

Windows listen attentively for the sound of broken glass.

[Anonymous]

Cerium oxide, combined with some water and heat, chemically bonds to the glass to fill the ultrafine scratches left behind by the previous abrasive (typically pumice).  That heat – which is a result of friction – may be what you are remembering.  That little bit of warmth (just warm to the touch – too much and you can thermal shock the glass) is a far cry from fire polish temps.

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Paul
FusedGlass.Org
Helios Kiln Glass Studio
PaulTarlow.com

 

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