Reactive BE Egyptian Blue like Steel Blue?
Posted: Fri Jan 23, 2004 4:45 pm
I just pulled out a platter from a slump firing and the field of Egyption Blue (0164) has light brushy marks that look like the pewter-like finish seen on a fired Steel blue (0146). I am absolutely certain that this glass is #0164 and not #0146.
First firing to full fuse was a uneventful. Piece came out fine, but with a bit of devit. Second firing was to full fuse temps (1500 F w/ a 10 minute hold). I added a few more pieces of glass, and I coated the surface of the piece with SuperSpray. It was a brand spanking new bottlle and I used a clean brush. At the end of this firing the piece was still clean. I have the expected reactions between yellows and oranges and lime green with this glass...but these are limited to where these glasses touch.
Final firing was a bend at 200 dph to 1200, no hold and an anneling segment. Now I see these slight, but present, brushy marks of steel blue like buff metal color. It's possible they were there after the first firing, but I doubt I would have missed it. I would think that the overglaze would prevent this kind of result, and don't understand why it would show up after the bend cycle and not before
I had two other pieces in the same kiln at the same time in the exact same seies of firings. These other two have Egyptian Blue elements, but not an entire field of blue...All three had been coated with the NEW Superspray, but only the one had the contamination, reaction... whatever you choose to call it.
The only thing different for this work over past work is that the overglaze is new.
The brushy look makes me suspect the overglaze, or that it wasn't a thourough coating...allowing the glass to oxidize a bit???? I am shooting in the dark here, but.... If the overglaze or brush were contaminated, why didn't I get similar results on the other two pieces on the Egypt Blue???
Anyone have this happen with Egyptian blue????
Any thoughts???
I'm charging the battery for my camera now, so I can take pictures and post them in a while if seeing it would be helpful.
First firing to full fuse was a uneventful. Piece came out fine, but with a bit of devit. Second firing was to full fuse temps (1500 F w/ a 10 minute hold). I added a few more pieces of glass, and I coated the surface of the piece with SuperSpray. It was a brand spanking new bottlle and I used a clean brush. At the end of this firing the piece was still clean. I have the expected reactions between yellows and oranges and lime green with this glass...but these are limited to where these glasses touch.
Final firing was a bend at 200 dph to 1200, no hold and an anneling segment. Now I see these slight, but present, brushy marks of steel blue like buff metal color. It's possible they were there after the first firing, but I doubt I would have missed it. I would think that the overglaze would prevent this kind of result, and don't understand why it would show up after the bend cycle and not before

I had two other pieces in the same kiln at the same time in the exact same seies of firings. These other two have Egyptian Blue elements, but not an entire field of blue...All three had been coated with the NEW Superspray, but only the one had the contamination, reaction... whatever you choose to call it.
The only thing different for this work over past work is that the overglaze is new.

Anyone have this happen with Egyptian blue????
Any thoughts???
I'm charging the battery for my camera now, so I can take pictures and post them in a while if seeing it would be helpful.