WarmGlass.com

Hi,
I am wondering if iridized and dichroic fused glass pieces are microwave and dishwasher safe. Is the coating on these glasses metalic? Can fused glass pieces hold up to the varied temperatures in the dishwasher?
Thanks!
Ginny

I once gave my sister a large carved bowl with maybe 900 little pieces of glass mosaic as tack-fused relief. A couple years later, I saw that bowl on her kitchen counter, full of fruit. (eeeek) I asked how in the world she kept fruit juices from sinking in between the mosaic pieces and she said, "Oh, I just dump it in the dishwasher whenever it gets dirty, cleans it right up."

I would never have put that piece in the dishwasher or used it as a fruitbowl--just goes to show that this stuff (if well-annealed) is a lot sturdier than we think. OTOH, dishwashing soap can etch glass and I still wouldn't put glass or crystal I really cared about in the dishwasher--over time it's going to start looking cloudy and scratched.

Microwave-safe I'm not sure about, at least with dichroic and irid surfaces. I've put smooth, transparent vessels without any raised decoration in the microwave successfully. But dichro and irid processes coat the surface with metal oxides, which might overheat or arc in a microwave. The way I usually test for microwave-safe is to put about a half-inch of water in the vessel, put it in the microwave and nuke it on high for about five minutes. I watch for arcing (you'll see lightning flashes inside the microwave) or that infamous pinging sound. If I don't hear either, then I examine it.

If it's abnormally hot, or has a tiny network of cracks or chips that it didn't have before, or any part of it has changed appearance (or if it's shattered)...it wasn't microwave-safe. Of course, this is a destructive test. If you don't want to lose the piece in testing, I'd just assume it isn't microwave-safe. And of course, even if it is safe, you must avoid subjecting it to sudden temperature changes.

I tell people NO...I can't imagine someone paying the price for a kilnfired piece and then being too lazy to handwash it.

DonMcClennen wrote:I tell people NO...I can't imagine someone paying the price for a kilnfired piece and then being too lazy to handwash it.

Imagine away! Had customers tell me the same thing. Guess my annealing is o.k., though my heart did skip a couple of beats...

The issue we worry about is thermal shock. Microwaves are notorious for uneven heating. That has to be a quick path to destruction. The fact that iridescence is a metallic coating doesn't help any. The dishwasher is a crap shoot. Water temperature in my machine could be different than it is in yours.

Float glass is different from the fusing glasses in 2 respects. First it has a lower COE which makes it easier to heat without shock. Borosilicate has a COE in the 30's. Float is in the 80's, and fusing glasses in the 90's. 2 factors that tend to cause problems are a tack fuse and different glasses, fused together. I have made float glass sushi plates for a restaurant that survived a commercial (at least 180ºF) dishwasher for over a decade of daily use. These had some colored frit tack fused to them. The second respect I was thinking about was the fact that usually, I only fuse glass from within the same sheet (or same factory case) However once you add a colored frit, you have the 2 glass thing happening. I usually wash bowls and plates, I make, in my dishwasher, before they leave my studio. They come out looking good. On the other hand, Don's advice makes perfect common sense.

I wonder if these same people clean thier paintings and other artwork with a pressure washer!!
Don

I have a lot of drinking glasses and bowls I have blown that i put in the dishwasher daily and have had no problems. haaven't tried them in the microwave. but my ty jut to see. they're made with glassesthat have good pecntage of metallic oxides in them. do you suppose 24% leaad crystal will do strange things in he microwave?

Fuhrman Glass Studios Inc wrote:I have a lot of drinking glasses and bowls I have blown that i put in the dishwasher daily and have had no problems. haaven't tried them in the microwave. but my ty jut to see. they're made with glassesthat have good pecntage of metallic oxides in them. do you suppose 24% leaad crystal will do strange things in he microwave?

while you are testing....throw a lead sinker in there and report back. might want to do all this when your s.o. is not home. rosanna

A woman bought a $500 bowl from me and asked if she could put it in the dishwasher. My response was "Would you put your Picasso through the carwash?" She got the message.

I made a bunch of cereal bowls from both Bullseye and Spectrum glass. I have used them daily and washed them in the dishwasher for months with no issues. I wouldn't microwave them, though. Like Bert said- uneven heat.

Wow, thanks everyone... I didn'tknow what to say to the gallery that I took some plates to. They found your responses quite helpful and sometimes humorous!Thank you

i'm doing a market this weekend, and the guy beside me has cutting boards (amazingly beautiful boards, at that). He and another woodworker were sharing stories, and he said that one woman bought 8 cutting boards, ran them through the dishwasher, and then complained to him because they bleached and wanted her money back. He offered to refinish them for her.

Like they say, "common sense ain't so common...".

Dana W.