devitrification

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  • #10126
    jocko
    Participant

    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

    #13312
    wordana
    Participant

    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

    #13313
    Stephen Richard
    Participant

    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/

    #13314
    Jolinda
    Participant

    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.

    #13315
    Anonymous
    Inactive

    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.



    Paul
    FusedGlass.Org
    Helios Kiln Glass Studio
    PaulTarlow.com

     

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