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Q: glass care ( No Answer,   5 Comments )
Question  
Subject: glass care
Category: Science > Chemistry
Asked by: garbs-ga
List Price: $2.00
Posted: 22 Apr 2004 15:15 PDT
Expires: 22 May 2004 15:15 PDT
Question ID: 334535
Can household cleaning chemicals penetrate the surface of glass?
Answer  
There is no answer at this time.

Comments  
Subject: Re: glass care
From: pinkfreud-ga on 22 Apr 2004 15:22 PDT
 
Hydrofluoric acid can eat through glass, but it's not considered a
household chemical.
Subject: Re: glass care
From: acrh2-ga on 22 Apr 2004 20:38 PDT
 
There are different types of glasses available to a consumer.  All
glasses (in a common sense) are made out of silicates (derivatives of
silicon dioxide = sand).  The only chemicals known to react with
glasses are hydrogen fluoride (fast) or very strong alkali (EXTREMELY
slow).  Neither is available to general public.  If someone were to
say to you that their glass was damaged through corrosion by a
chemical, you had better assume that the glass was less than 1/64 inch
thick.  Can household cleaning chemicals penetrate the surface of
glass? The answer is no.  Think about it this way: chemistry lab
glassware is made out of glass (very similar in properties to glass
you know, differences from it being higher heat resistivity).  Now,
who would want to use glassware that would not hold its chemicals?
Subject: Re: glass care
From: acrh2-ga on 22 Apr 2004 20:53 PDT
 
I read the comments from "Cleaning on glassware" question.  They are
mainly accurate except for one point, which is important.  Acids do
not attack glass.  Hydrofluoric acid, or hydrogen fluoride, is the
only one acid that does.  But important issue to understand here is
that the emphasis is on FLUORIDE, not acid.  It is the fluoride that
likes to react with glass, the acid part is just a promoter.  Hence,
none of the acids (including hot phosphorous acid, contrary to what
the link states) will damage glass, let alone penetrate it.
Subject: Re: glass care
From: acrh2-ga on 22 Apr 2004 21:06 PDT
 
Ok, the only reason why I'm here is because I've had a few beers and
had nothing to do for half an hour.  Being a Ph.D. chemist, I have to
correct a few mistakes that I have made.  1) Phosphoric acid, not
phosphorous acid. 2) I didn't know that hot phosphoric (IC!) acid is
believed to attack glass.  And I still don't believe it, though many
sources on Google say that it does.  I bet phosphoric acid would have
to be heated to boiling to have any noticable effect on glass
surfaces. Someone must have screwed up while describing its effects on
glass, and now, everyone is repeating it (which often happens in
science, published in obscure journals by obscure authors from obscure
countries).  After all, why would chemical manufacturers sell
concentrated phosphoric acid in glass bottles?
Subject: probably not
From: nanoalchemist-ga on 06 Oct 2004 10:03 PDT
 
acrh2-ga is correct about phosphoric acid etching glass

http://www.glassonweb.com/articles/article/219/
Chemical Air Pollutants 
Certain airborne chemicals can also deteriorate glass surfaces.
Although glass is resistant to most acids, some forms of hydrofluoric
and phosphoric acids react quickly with silica present in glass. There
are also other chemicals than might attack glass surfaces. When these
substances are in the form of airborne sprays they can be carried for
longer distances through the assistance of natural elements. They can
be carried not only to industrial, but also to rural and residential
areas.

The question then becomes "does phosphoric acid count as a 'household cleaner'?"

according to the NIH, yes, it can be.
http://householdproducts.nlm.nih.gov/cgi-bin/household/brands?tbl=chem&id=93

Overall, glass is pretty inert, and not likly to react with much. For
cosmetic purposes, you may wish to avoid abrasive cleansers, which may
phyisically scratch the surface of the glass.

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