Topic: Iridisation of glass - can it occur naturally?

[David E]

I know that red wine(?) can cause iridisation to the inside of decanters and carafes, but does anyone know if this effect can occur naturally to the outside of glass? The reason I ask is because I have an item of glassware where it should not be present, but it exists very faintly. So was this deliberately done, or a natural cause?

[Lustrousstone]

Could be the dishwasher...

[David E]

Hmm, possible... but then I would have expected the gilt bands to have worn badly.

[chopin-liszt]

The dishwasher will do it; I don't know about the gliding - maybe that takes longer to come off?
Burying it for a thousand or so years in soil containing appropriate minerals would do it too.

[Ivo]

Metal salts in earth and sewage will do it quite fast, it does not need hundreds of years to achieve a lustre effect.

[johnphilip]

OK David i offer my body and organs up for research into red wine and its effect on glass if it will help , just bury me beside a bottle,,,,  make sure its a good year and full . not near the sewage outlet please . jp

[chopin-liszt]

oooh, Ivo -
"Metal salts in earth and sewage will do it quite fast, it does not need hundreds of years to achieve a lustre effect."

now you've given me ideas.........

[David E]

I always thought gilding, particularly on vintage (or should I say vintique ) glass was highly prone to wear in a dishwasher. I would have thought it would take many, many washes to achieve this level of iridisation and then the gilt would have vanished.

So is there some air-borne chemical, perhaps a naturally occurring one, that could achieve this - I assume the presence of metallic salts that normally produces iridised glass. Perhaps it was left in a garden shed or something?

If not, then the only conclusion I can draw is that it was done deliberately as an effect.

[Ivo]

I've seen the combination of very light iridescence and gilding in Polish tableware.

[johnphilip]

David i am sure the guy who makes the repros for museum shops can help with this one i believe his name is Mark Taylor he has a partner who works with him .