Author Topic: Technique of the day...Stretched Glass  (Read 745 times)

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Technique of the day...Stretched Glass
« on: February 02, 2019, 12:49:57 PM »
I'm going to try and keep up with a goal of adding a technique to this board daily. More when I find a treasure trove of them. ;D The Craftweb General Discussion area is a bit of a nightmare to try and find anything. I have learned a few ways to search it and actually took a week to read the entire archive. I found so many nuggets shared in there that it seems a shame they they all stay hidden.

Here's a first...Stretched Glass or the Imperial Stretch discussed back in 2012.

Pete Vanderlaan: "Imperial stretch" is a technique of spinning a bowl after it has been fumed with stannous chloride. The spin makes the irridized fumed surface "stretch into a regular cracked fume radiating out from about four inches towards the center of the bowl out to the lip.

Important points:
- Stannous chloride is pretty nasty and highly oxidizing. Ventilation is important.
- Mix up a 30% solution in isopropanol (30g/100ml). Add some muriatic acid to help get it dissolved (just a quick splash).
- Get a Critter Sprayer with stainless steel components. This uses a Bell jar as a glass container and compressed air as the spray source. This stuff will break down aluminum and normal steel in no time. Stainless lasts but not forever...buy refurbish kits to keep you spraying.
- When spraying get it out of your area ASAP. I set up a fan that gets it into the ventilation hood flow. If you are spraying near anything steel (MARVER!) it will rust.
- Stannous likes a reduced surface. Hit your piece with a fluffy, weed burner and then spray it from a few feet away. Flash and Repeat. Don't over do it or you will chill it.
- Usually stannous is performed right before boxing, but this technique requires continued working after application. Get it on the punty and spray it before spinning out.
- Heating a stannous sprayed piece for long times in the glory will remove the irridization to a degree. It will be most successful if you can limit heating cycles in the glory...perhaps spot heating the lip using a torch at the bench.



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More on stannous fuming
« Reply #1 on: February 17, 2019, 11:13:07 AM »
I found this little diddy in reading about overlays using stannous fuming.


Eric Miller:

Pete...could one just do an overlay of silver clear and reduce it, then gather over it for a simliar effect?

You will get a good deal of the effect that way. Silver in local reduction will be way too strong at normal concentrations. I would think that silver in oxidation( just put it in clear glass) would then reduce in the gloryhole under a reducing flame. It will be streaky that way but fairly light. it develops as you keep reheating it. You could also fume those same gathers with stannous chloride and case them.

Strontium in tin chloride would yield a reddish fume.

And a little typical VanderLaandian player hating:
"I suggest haunting the Rakow if you plan to go to GAS at Corning. The library is worth the trip alone. Screw the demos."   ::)

This strontium bit is interesting and jumped out at me. While I can't say for sure, it sounds like adding some strontium to a stannous spray will redden the fume. OR if the base glass has strontium the result is red? I'll have to try it.

BTW...it has been noted that other metal chlorides can be used as a metal fuming etch. Iron chloride works and is suppose to give a slightly different color. I've used it but didn't see much change.

Here's another fume spray possibility:
Terry Crider suggests...
Engelhard Corp. in NJ 800-542-6684 has an iron Thermo Luster (amber A 2612) that works great.