Topic: Murano Uranium Sommerso Fish

[NevB]

I can't find another the same but the triangular base and and style are similar to signed pieces by Licio Zanetti. This one's 14" tall, weighs 3 3/4lbs. and is in 6/7 colours.

[chopin-liszt]

    Fabby!

[NevB]

Thanks Sue, and even fabbier in the flesh. I bought it in an antiques arcade and the seller called it "Murano style" and "A/F" because of a small chip on one of the fins, it wasn't expensive 

[chopin-liszt]

It's like having your own private aurora sitting there to gaze and wonder at.
A completely joyful piece. 

[NevB]

More photos 

[Lustrousstone]

I hate to say this but I think your glow is manganese in the colourless glass. I can't see a hint of yellow or green

[NevB]

Christine, I'm trying to establish whether uranium glass can be clear and colourless, a couple of online sources say it can be but I can't confirm it. Also with sommerso pieces containing uranium the glow seems to infuse into the glass surrounding it, confusing things. This fish does glow clearly and brightly under UV.

[Lustrousstone]

Uranium glass can't be colourless. Uranium with no other metal compounds (colorants) present is always yellow; even in low concentrations, it is a pale yellow and will glow a bright green. There is no point in having expensive uranium and making colourless glass. Your glow is quite dull really. If you are using a 365 nm light it will give you false positives for uranium because manganese causes a much brighter glow at 365 than it does at 395. Manganese was often used in the basic glass formula, even if colorants were going to be added. If a 395 torch shone on your item from 4 or 5 ft away does not cause a reaction in daylight, it isn't uranium. Online sources that cite uranium in colourless glass are either hopeful or trying to flog colourless glass (there is an Etsy shop stocked with nothing but colourless glass that shows bright-green-under-UV pictures and claims falsely that it is uranium glass).

[Ekimp]

Referring to the article by Barrie Skelcher for the Glass Association:
https://www.glassassociation.org.uk/sites/default/files/Uranium_Glass_sample_article.pdf

Uranium with no other metal compounds (colorants) present is always yellow;

Skelcher seems to say the colour of uranium glass depends on the type of uranium compound used (such as uranium nitrate or sodium diuranate) in addition to the chemistry of the host glass, so not always yellow when used without addition colourants? [ref. page 1 para 3 and page 4 para 4]

There is no point in having expensive uranium and making colourless glass.

Skelcher says there are lots of examples where uranium was used for no apparent reason in coloured glass, where it wasn’t needed as a colourant. So it was used when not necessary even though expensive, presumably they could’ve done the same in clear uranium glass if there is such a thing. [page 4 paras 4 to page 5 para 2].

If a 395 torch shone on your item from 4 or 5 ft away does not cause a reaction in daylight, it isn't uranium.

The reaction to uv light source is a good indicator for uranium content but isn’t a definitive test. Glass with uranium content doesn’t always fluoresce brightly. [page 3 para 3 and plates 2 and 3; also https://www.glassmessages.com/index.php/topic,72609.0.html ]

[Lustrousstone]

!. Note that Barrie says colour, not lack of colour. He also uses the word "may" in relation to green uranium glass.
2. In my 20+ years' experience, there are very few uranium glass colours that do not benefit from the use of uranium. It gives a richness that you don't see in a similar shade without uranium. Even grey glass has the benefit of a brightening of the colour. See here http://lustrousstone.co.uk/cpg/displayimage.php?pid=892. No it won't be in colourless glass. The main and largest batch in a glass factory is clear. To reiterate, uranium salts were and are expensive, as is the case with many colorants.
3. No uranium glass doesn't always fluoresce brightly but get up close and it does in my experience and quite differently to manganese containing glass. And you get a faint reaction from further away, possibly one a camera cannot capture. In addition, a black light 150 W bulb, which is what Barrie is citing, is actually pretty useless at producing the best UV wavelength for uranium, also in my experience.