Grey Line

One of the discussions on the bullseye forum that a few of us are having is around where some discolouration – grey line – is appearing at the edge of some of the glass after a full fuse.

So I have put the photos here for viewing as part of the discussion.

If you look carefully at the red plate on my previous blog at the top of the virtical where the red meets the yellow. You will see a grey line where I joined two clear pieces to form the top layer.

Harder to show is that there is often a grey line around the edge of a piece. Various recommendatsions have been made so I did the following test.

Two pieces 3 by.5 inch. 2 layers, thin clear and colour base. both items had all its sides ground, one set was immediatelly put in to water bath. From the photos I cannot tell which was which as both have grey lines.

About alfeze1

Although computing has my way of life and has been for the past 30years or so my loves are; making things inc many arts and crafts, gardening, photography, birds and wildlife and the occasional bit of sport like skiing... or at least apres ski:-) We are also involved with the NWPG and the Kennet and Avon Canal Society and crew occasionally on the Rose of Hungerford. A canal boat that runs public trips to raise money for work on the Kennet & Avon Canal. In a few months I hope to leave behind computing, and devote myself to creation instead of just fixing. I will them start to publish on a more regular basis.
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1 Response to Grey Line

  1. chatterglass says:

    The grey line is is a consequence of grinding the edge of the glass. At a microscopic level the ground edge looks like a jagged mountainous area. Once fused, those mountains “collapse” and trap tiny bubbles of air. You can get the same effect (very visibly) by putting a shallow heap of clear powder frit onto a piece of black glass. If you have a strong magnifying glass (or dissecting type of microscope) you’ll see millions of tiny little bubbles. By the way, this is not the same as devitrification. The solution to the problem is to either avoid grinding the glass edge, or if you must, use diamond pads (eg Diapad from 3M) to progressively reduce those mountains into little hills before firing.

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