Both the black and foxy red trace paints are well fired, are glossy, and are firmly fused to the surface of the glass.
They should last five hundred years.
We cleaned the surface dirt from two small areas of both coloured tracelines using de-ionised water and cotton buds. Under reverse lighting it was immediately clear that both trace paints were highly glossed and had formed a good fused bond with the surface of the glass. The reflection of light from the glass paint is identical in colour and gloss to that which we fire in our kiln, and which we can electronically control to within 1ľC. Photos 19, 20 and 21 show the cleaned area in transmitted, semi and fully reverse light. Photos 22, 23 and 24 show the same of the foxy red trace.
Our observations about the glossy fired well fused nature of these trace glass paints was confirmed when we probed them with a fine metal point under a 10X magnifying lens and found we could not pierce the surface of the glass paints. This confirms good and correct adhesion.
The second layer of glass paint is not stable.
The bulk of the second glass paint layer may last another 300 or more years under current conditions.
The areas where we most closely examined this second layer were where the third layer has washed off. One such area is that on the withers of the pony (Photos 25 and 26) where an area approximately 50mm x 15mm is clear of the third paint layer. Others are the cleaned mustard figure’s face in the “Resurrection” window, and the left side of the central vertical band of the Bishop’s mitre. As there were no tracelines in these areas, and as the entire third layer had washed off or been removed, this allowed us to very closely examine the only layer of glass paint which was the second layer.
We studied this second layer under transmitted and reverse light, using the 10X lens, the metal point, and de-ionised cleaning. We investigated the condition of this layer of glass paint for two hours as it was imperative to “get it right”.
We found that while this layer was sufficiently stable to not be removed with a cotton bud and de-ionised water, it could be removed with a metal point. The second layer appears to be not fully fused to the surface of the glass, and is only semi fired. This underfiring appears to be the condition of that second layer throughout the window – on