Reactive BE Egyptian Blue like Steel Blue?

[Cynthia]

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.

[Amy on Salt Spring]

I've had trouble with Egyptian Blue--sometimes it has that metallic sheen on it and sometimes it doesn't, no predicting why. It only happens (when it does happen) with more than one full temp. firing, never on a first firing or at least not for me. I never use overglaze though so I can't help you with that. I'm told capping works for both Steel Blue and Egyptian Blue after its gotten that effect but when its happened to me capping wasn't appropriate so I never tried it.
-Amy

[Cynthia]

http://community.webshots.com/album/62967227AfKlWJ

This site links you to some images of the problem piece. The first two images show the problem, and the survivor.

I am thinking that it resulted from an inadequate coating of the overglaze, but any input, specultion or real experience like Amy's would be appreciated.

I'd rather make this happen rather than have it happen

Thanks

[Lisa W.]

Cynthia,
Went to your weshots and saw "Charlott 2". Is that a hanging piece? I have these tiles 4x4 that i have made and was wondering how to hang them 3 down and maybe two across. I have drilled a hole in top and bottom for the hanging but in my search can not find anything appropriate for hooking them together. This is cathedral glass and I need the light to come through.
Any Help.
Lisa

[Cynthia]

...saw "Charlott 2". Is that a hanging piece? I have these tiles 4x4 that i have made and was wondering how to hang them 3 down and maybe two across...

Lisa, "Charlotte" is a hanging piece. They are (tiles) fired with cross chanels between the glass in order to thread the pieces together. It is a technique I learned and used from the book "Creative Glass Techniques" by Betina Eberle. I used fiber paper placed between two peices of glass and simply reamed the paper out after firing to leave chanels within the glass.

I have also used nicrome wire placed in the center of each side ("U" hooks). You can then wire or use jump rings through the loops to connect the tiles together. It's a matter of what look you are wanting, and how heavy the piece will be to determing which approach you take (the chanels are stronger when the piece will be weighty). You can take varied approaches to either of these methods and modify them to meet your needs.

Experiment .

[Lisa W.]

Thanks Cynthia,
I did not want channels in the class, so I was thinking more on the jump ring idea.Sure wish I worked with metals. Let ya know how it comes out.
Lisa