devitrification on bottles

[kpearman]

Some bottles I flatten have devitrification especially the blue ones. I usually heat the bottle to 1325 for 30 minutes. I have tried hotter temps for shorter periods but still get the same devitrification. I tried a borax solution but this did not help – in fact it became worse. Any good solutions?

Thanks.

Keith

[Stephen Richard]

720C is right in the middle of the devitrification zone, so soaking for 30 minutes there is not a good idea. Try a long soak at ca. 677C or a quick one at 760C.  But the main thing is to have every thing very clean.  Contaminated surfaces, even if only a little, on bottles and float glass lead to devit very easily.

Stephen Richard

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

[kpearman]

I usually clean with isopropal alcohol. Is there something better?

Keith

[Stephen Richard]

If you have water without lots of minerals in it use it.  Otherwise do the final rinse with distilled water and polish dry.  But you will still have a portion of the bottles devitrifying – it seems to be tne nature of bottles.

Stephen Richard

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

[Anonymous]

Isopropal alcohol comes in different concentrations – typically 70% and 91%.  Use the 91% (most pharmacies carry it – and it doesn’t cost a lot more).  The non-alchohol portion can contain oils that don’t help.

As Richard suggests, buff your glass clean as a last step.  Use a clean, cotton rag.  Make sure it wasn’t dried using dryer sheets – they leave residue in the fabric that transfers to the glass.

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Paul
FusedGlass.Org
Helios Kiln Glass Studio
PaulTarlow.com

 

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