lens cleaning

[SidW]

I recall reading somewhere, but have lost the reference ...

... that the fungi that thrive on glass emit the acid to dissolve the minerals it feeds on. The acid gets left behind and continues getting the next meal ready. Supposedly the answer to most photographers' (and lab technicians') puzzle, how does fungus eat glass? It doesn't, the glass is just the menu, or the restaurant, the fungi pick and choose a mineral it needs for the moment.

Some links I still have, in addition to Ron Herron's:

www.chem.helsinki.fi/~toomas/photo/fungus/

www.biotech.ufl.edu/EM/data/lenseatingfungi.html

www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/artjul04/pjfungus.html

Be careful with the last one, it's long and it'll probably split.

[Stephen]

The other side of the use of hydrofluoric acid, it was used in the production of Galle and Lalique art deco glass items, in the case of Galle to produce cameos from multi layered glass, or producing the mist effect in Lalique glass. Dangerous stuff in the concentrations used. It also comes from overheated Viton O rings, and PTFE, yes, the non slick pans! If taken too high in heat, it releases the acid, which fumes as well.

[hansz]

As this thread is also about HF, it is time to mention the extreme toxic behavior of HF.
Only use it within controlled environments, use proper labarotory gloves, use teflon as a container and NEVER NEVER get it to touch your skin! If so, run for the hospital!

Only from experience: I used to separate AL2O3 (sorry, no subscripts here) - that is Corundum (Ruby and the non-red variant Sapphire) from its granitic environment; literally boiling the granite by submerging it in concentrated HF.
Quite spectacular...

Hans (MSc geology, mineralogy - once; now turned into a grumpy IT specialist:-)

[Stephen]

Sept 30, 2012 15:29:28 GMT -5 hansz said:

As this thread is also about HF, it is time to mention the extreme toxic behavior of HF.
Only use it within controlled environments, use proper labarotory gloves, use teflon as a container and NEVER NEVER get it to touch your skin! If so, run for the hospital!

Only from experience: I used to separate AL2O3 (sorry, no subscripts here) - that is Corundum (Ruby and the non-red variant Sapphire) from its granitic environment; literally boiling the granite by submerging it in concentrated HF.
Quit spectacular...

Hans (MSc geology, mineralogy - once; now turned into a grumpy IT specialist:-)

Can you imagine the conditions in the turn of the century French glass factories, where all the finishing and etching was done with HF at high concentrations?

[hansz]

The mortality rate must be very high indeed... Almost impossible to imagine.