Author Topic: acid removal of heavy scratching on u. glass.  (Read 788 times)

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Offline Paul S.

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acid removal of heavy scratching on u. glass.
« on: January 06, 2013, 04:36:10 PM »
sorry to drag this one up again.             Bought this Webb's Gay Glass Sunshine vase early yesterday morning, in the rain (always fatal) - and dried it when I got home only to discover that the bottom two inches or so of the inside are very heavily dulled and scratched as can be seen in the pic.                        This is way beyond my abilities to bring back from the dead, partly because of the composition, and partly because the scratching is severe, so wondered - in view of Neil's comments (below) re the professional use of acid - if this damage might be cured by a few dips in hydrofluric or whatever they use.           There's no backstamp or cutting for the acid to damage, so could be a goer perhaps?  -  or might it be that acid won't remove sufficient glass to cure the problem.   
About 6.25" - 160mm tall.                 I may decide to pass it on if the concensus is that acid won't help, but it's a great piece and I did want to keep if poss.                     All thoughts welcome, and thanks for looking  :)

Neils's comments were part of a Cafe disussion from the 28th November last year.

"Hi, the restorer I mentioned only works for the trade.  I'm happy to take it in for you if you either a) want to mail it to me - send me your email address and I'll provide shipping details; or b) let me know where in the UK you are, and next time I'm in the area I'll pick it up from you to save you the shipping costs.  In either case I only visit the restorer about once per month, or every other month, so turn around time won't be quick I am afraid.

The professional restorers use Hydrochloric Acid to take off residue but this is incredibly toxic so be very careful if you use it.  If the acetic acid (vinegar) took off 80% of the staining then you might just want to leave it in there a lot longer to take off the remaining 20%.  If it will come off then prolonged exposure to the vinegar should work.

Hope this helps"


Offline Frank

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Re: acid removal of heavy scratching on u. glass.
« Reply #1 on: January 06, 2013, 06:08:53 PM »
Acis is not the solution, grinding and polishing is.
Frank A.
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Offline Paul S.

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Re: acid removal of heavy scratching on u. glass.
« Reply #2 on: January 07, 2013, 08:35:03 AM »
thanks, and no doubt that would be a solution  -  it was just that I didn't consider it a safe propostion to grind and polish this type of glass. :-\


Offline aa

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Re: acid removal of heavy scratching on u. glass.
« Reply #3 on: January 07, 2013, 07:39:03 PM »
I recently discovered "micro-mesh". This is used by picture restorers, among others, and basically starts off where "wet and dry" leaves off. It is really quite amazing. Also quite expensive, relative to other abrasive media but definitely worth it. Whereas "wet and dry" grades go up to 1200 mesh (2400 and 4000  are difficult to find) micromesh starts at 1500 mesh and goes up to 12000.

If you go through the grades, and are prepared to take the time, you can polish scratches and water damage out.

This is actually something you can try at home, but it needs a lot of elbow grease!
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Offline Paul S.

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Re: acid removal of heavy scratching on u. glass.
« Reply #4 on: January 07, 2013, 07:52:30 PM »
hello and thanks for the mention of 'micro-mesh', which I recall having seen advertised before - seem to remember that the finer grades are designed for polishing perspex or similar.         However, my concern was for the fact that I'd probably not attempt a piece such as this in view of the uranium content, although the professionals might have a process that avoided any health risk. 


Offline johnphilip

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Re: acid removal of heavy scratching on u. glass.
« Reply #5 on: January 08, 2013, 09:31:03 AM »
A well known restorer once told me if the scratches were very deep you may just end up with polished scratches . hmmmmm  :-\


Offline Frank

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Re: acid removal of heavy scratching on u. glass.
« Reply #6 on: January 11, 2013, 12:30:45 PM »
Polished scratches are ok. You can then call it cut glass  8)
Frank A.
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Offline Nemmie

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Re: acid removal of heavy scratching on u. glass.
« Reply #7 on: January 11, 2013, 12:45:07 PM »
Thanks for the micro mesh tip. Just used it on a vase that has been bugging me for years.

Worked like a charm and only took half an hour of rubbing with various grades.

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Offline Frank

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Re: acid removal of heavy scratching on u. glass.
« Reply #8 on: January 11, 2013, 12:57:35 PM »
Micro-mesh themselves say
Quote
Glass has a much harder molecular structure than acrylic or polycarbonate and although some damage might be abe to be removed, you would be unable to polish it back out to optical clarity...
but this might be good enough for glassware as Nemmie attests.
I guess you could you use it in water for U glass, preventing airborne particles.
Frank A.
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Offline Nemmie

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Re: acid removal of heavy scratching on u. glass.
« Reply #9 on: January 11, 2013, 01:22:23 PM »
The vase had a ring well more like a double ring or several rings from water sitting in it.

Nothing else I have tried over the years had made any difference so I am very happy. I suppose fogging would be a different matter.

I wish I had taken a before pic because the transformation is really impressive.



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