Author Topic: Iridised superlight item (Read 4210 times)

Ivo · « **on:** March 11, 2007, 12:35:19 PM »

Superlight glass candlestick / Vase (the opening would just about fit a feather, having a hard time deciding which side is up) with cheerful iridescence. Anyone ran into this type of glass before?

http://glassgallery.yobunny.org.uk/displayimage.php?pos=-5580

Andy · « **Reply #1 on:** March 11, 2007, 03:50:29 PM »

Ivo,
im sure ive seen something recently, checking my books whilst watching the Rugby

It may have been while i was looking for stuff by Fritz Heckert, c1900.
Theres no vaseline glass in the stripes on the foot are there

Andy

Harrach

http://www.great-glass.co.uk/library/lib1c.htm

Ivo · « **Reply #2 on:** March 11, 2007, 07:27:45 PM »

Quote from: Andy on March 11, 2007, 03:50:29 PM

Theres no vaseline glass in the stripes on the foot are there
Andy

Thank you for looking. There is no vaseline and no stripes; the glass is fully transparent, optically ribbed and iridised all over. My suspicion is modern, maybe Russian...?

Andy · « **Reply #3 on:** March 11, 2007, 08:24:45 PM »

Ivo,
did you check this

Harrach

http://www.great-glass.co.uk/library/lib1c.htm

I added it a bit later
Cheers
Andy

aa · « **Reply #4 on:** March 11, 2007, 08:31:45 PM »

I'm assuming this is lampwork?

The Conran shop has had a lot of similar stuff recently, but not irridised. I can't find a link to the smaller pieces, candlesticks etc, but here
is a link to their lamps http://www.conranshop.co.uk/ProductDetails.aspx?pid=231923&cid=Decorative&language=en-GB
Not a great image, but the whole thing from the shade to the base is one piece of lampworked glass, presumably done a lathe, although they describe these as handblown.

I think the irridescence may be a cold spray.

Ivo · « **Reply #5 on:** March 11, 2007, 09:15:59 PM »

Andy: - yes I checked the Bimini items but this is not very similar; I have a good piece of Bimini to handle and the material does not feel the same.
Adam: - That is close in shape - but that lamp would be borosilicate, perhaps?
- Is there a way to tell sprayed on cold iridescence from hot??

aa · « **Reply #6 on:** March 11, 2007, 09:54:31 PM »

Yes, the Conran ones are borosilicate and presumably lampworked. If yours is super light then I would think it was lamp-worked too.

However, most people assume that borosilicate is only used for lamp-work, but it is possible to hand-blow it from the furnace.

I don't know enough about irridescence techniques, having never really used them. However, if you spray on something like Stannous Chloride, which is what most people do, while the glass is hot, you can often see a sort of crystalline structure, particularly close to the rim. I think, this is because there is a marginal degree of movement on the surface of the glass, when it is reheated, but the stannous chloride doesn't move, and therefore breaks up. However, it could also just be the nature of the stannous chloride crystals. I am not sure.

With a cold spray, which is used to give a pearlised effect on an annealed piece, the irridescence is much more like an oil on water effect.

Hope this helps. It would be easier to describe if I had two reference pieces in front of me and could point out the difference!

Glen · « **Reply #7 on:** March 13, 2007, 08:10:01 AM »

I am not familiar with cold applied iridescence, but I can tell you a bit about the application of iridescence (dope) to hot glass.

Different chemical solutions may be applied: for example, stannous (tin) chloride, ferric (iron) chloride or a combination of the two. The temperature of the glass has an effect on the appearance of the resultant iridescence - a matt or satin like appearance will result if the glass is very hot, while a shinier effect will result if the glass is not quite so hot.
iridescence - http://www.geocities.com/carni_glass_uk_2000/iridescence.html

If shaping takes place after the application of iridescence it will give rise to a stretch effect. The surface of the iridescence crizzles and produces an "onion skin" look due to minute breaks occuring on the surface of the dope.
Stretch effect - http://www.geocities.com/carni_glass_uk_2000/Celeste.html

Iridescence applied to hot glass ("burnt on") is very durable and would only be removed if you damaged the actual surface of the glass itself. On the other hand, I imagine that any iridescent coating applied to a cold surface could be fairly easily removed.

Glen

Anne · « **Reply #8 on:** March 13, 2007, 01:52:51 PM »

Glen, you're right about cold applied, I'm sure. We have some tumblers which were irridescent blue when we bought them. They are now totally clear glass, courtesy of the dishwasher!

(Luckily they were not expensive or special!)

Frank · « **Reply #9 on:** March 13, 2007, 08:56:07 PM »

There are modern coatings that are almost as fast as heat fused coatings.

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