Glass Etching/Damage 4

[Ron]

I am investigating an etching issue on some window glass in a building. I'm fairly sure that the etchant is hydrofluoric acid because of the rapid attack on the glass surface. Phosphoric acid would not have produced the same "signature" of damage and I don't know of any caustic material that will etch glass in this manner.

The damaged glass is on the exterior face of non-operable windows that were installed in a building under construction. I suspect that one of the subs has used some material in their process that contains HF acid. Thus far a review of the MSDS sheets has not revealed any such material, but we also do not have MSDS's for all materials.

My question: Do any of you know of a tinning flux, soldering flux, cleaning, or patina agent for copper or galvanized steel that contains HF? I have found a few things related when I Googled several search terms, but was wondering if anyone here knows of a specific material related to the soldering, cleaning, or preparation of copper or galvanizing material that would contain HF.

 

[MintJulep]

HF acid gel "pens" are readily available for use in etching glass for signs, windows and art.

They are commonly used by vandals make "etchitti" on glass.

Is your damage accidental in appearance, or deliberate vandalism?

 

[tomwalz]

Black Flux and White Flux for brazing are potassium salts of Boron and Fluorine. The fumes will etch glass nicely. It takes very little exposure to ruin a pair of eyeglasses. In the case of eyeglasses it creates a pattern of very small dots (maybe 0,003” to 0.005”) or a speckling.

Tom


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[Ron]

MJ...pattern is consistent with carelessness on construction site.

Tom...no brazing was done, but a lot of soldering of copper roofing materials and welding on galvanized structure. I would anticipate that other fluxes would contain similar materials, so I'll check that as well.

 

[EdStainless]

Any stainless steel trim on the building? When people weld SS they often clean up the heat tint on the welds with pickling paste that contains HF.

Remember, it could have been on the glass and dry before installation. Then once exposed to humidity attack kicked in.

Sure it couldn't be caustic?

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[swall]

Some aluminum cleaners also contain HF.