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For various reasons, I need to fire irid face-down. Bullseye confirmed that there can be problems firing it face-down onto thinfire, so I did it on a kiln-washed shelf. But...same problem
(markings). Has anyone had this problem and resolved it?
Thanks.

Because the sheet glass is handmade, there are inherent bubbles, texture marks (sometimes called zipper lines) in the glass. The irid accentuates the look of those 'imperfections', in my opinion. Once fired, I can't imagine anything you can do to change the look of them, unless you re-fired on a heavily textured base like fiber, which would obviously change the look you're after.

I've fired irid on Thinfire in the past, and haven't had poor results, but I like the sheen irid gets by firing directly on the shelf. For this reason, I carefully examine my irid and cut around any offending marks.

I am looking for prevention, not remedy. I will see if I can detect a pattern to the pits and marks...it doesn't happen every firing.

I have been experimenting with firing wissmach irid recently.
I fire both face up and face down. I find that face down is more predictable, but both yield excellent results as long as you don't fire too high.
these are some experimental pieces trying to use mica on irid. Have done more and better on pieces since these, but these pics were available.

thanks for chiming in, Barry. are you firing on thin-fire or kiln-wash? and what temp are you saying is the safe one, to avoid this issue? (maybe you haven't encountered the issue). actually your comments are helpful because this is for a first firing of 3, and I have been going to 1480, but could go lower, like 1400, if it made any difference.

Yep on thinfire.
Fire first to 1400 range....actually about 1425- in my small kiln. In the larger one I fire at 1375.

Barry

it may be different for your smaller jewelry sizes pieces, than my blanks, but I will try not going over 1400. thanks.

Nina, the other option is uroborus machine rolled irid, i LOVE working with their machine rolled glass and their irid has good color all across the sheet.

D

Thanks Dee, but wouldn't the same problem arise?

I have some of the machine rolled URO irid that they misshipped several years ago. Never thought to try it. Will do so.
The color of their irid is more uniform across the glass (does change, but more of a gradation)
Wissmach is very random. Produces great results as long as you can preserve the color.

Barry

nina......may I suggest.......I spray Bullseye kiln wash on a freshly ground and cleaned shelf when I am firing irid down. I fire it to 1410 with fabulous results. Spraying gives it a different look then thin fire or brushed kiln wash. Be careful if you try this to not touch the surface of the shelf after spraying.

Laurie, thanks for the tip. I never sprayed kiln wash, but I will try this, because I fire irid face down a lot.

barry, who is selling wissmach irid? the colors look great!

Dee,
Don't know. Call Wissmach to find out. I bought several sheets direct and that will be a lifetime supply.


Barry

Nina Falk wrote:Laurie, thanks for the tip. I never sprayed kiln wash, but I will try this, because I fire irid face down a lot.

I've been using this airbrush for years: http://www.chicagoairbrushsupply.com/pa62sphe.html

I have a large supply of the same bottle that is used with the sprayer so I can premix 20 or 30 bottles with KW & water. That way I always have it at hand when I need to spray a shelf. Just shake and spray at about 40 psi. Usually one bottle will cover a 21" shelf.

If you need more info or pictures let me know.

Jim "The Hobbyist"

Jim, I have the same airbrush, also purchased from Chicago. Where did you buy the extra bottles, please? Chicago doesn't show them on their site. Jen

I bought a large supply of them many years ago when I first started playing with glass. They were a handy way to sort and store all kinds of things like frit, powder, gems, scraps, pills, spices, etc.

Later, when I saw the Paasche 62 airbrush it looked like they would fit. Sure enough, they will screw on just like the one supplied with the airbrush. Better yet, the bottles came with caps, supposedly sterile for food/medicine use. So I can premix a whole bunch with KW & water, cap and be ready to spray at a moments notice. I save the used bottles and when my supply of premixed gets low, I just refill them. I believe I put in about 30 - 40 grams of KW and then fill with water. That may include the weight of the bottle I would have to double check.

I have enough of them that I can sell you (or whoever) some. I can't remember what I paid. It's been a long time but my guess is somewhere around 50¢ each. If you want some (10, 20, 30?) let me know and I'll sell them to you for that same price plus postage.

Jim "The Hobbyist"