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Protecting white agate while polishing

Hi all, does anyone know how can i preserve a white agata from
buffer’s polishing compounds stain?

Alberto Ruperti (italy)

Are you polishing the stone or the metal it’s set in? I’m assuming
the latter for this response. I’ve never experienced any problems
using my ultrasonic to remove rouge stains from hard, dense materials
like agate. If there are deep cracks or other compound-capturing
recesses in the stone, that could be a problem. I’d need more
about what you’re doing and a description of the agate
before going further.

Rick Martin

Hi Rick, thank you for your attention, yes i am polishing the metal
with the agate set in. the problem Is that agate absorbs the
polishing compound’s colour. I’ve tried to preserve the stones with
a liquid coloured ( a swiss product used in watch industry) but
without any success. Is there something like transparent coat to
protect the stones? The ultrasonic cleaning don’t remove the dark

Alberto Ruperti

Hi Alberto,

Is there something like transparent coat to protect the stones? The
ultrasonic cleaning don't remove the dark spots. 

Were it me I’d experiment with using white rouge and other light
colored compounds to avoid staining in the first place. I don’t know
what products are available to you but there are several such
compounds here in the States. Maybe others will have better

Good luck.
Rick Martin

Alberto…Without more it is difficult to know just
what the situation is. However, I find that sometimes when I need to
protect a stone or another piece of metal, patina etc, I cover the
piece with masking tape before polishing. The tape is easily removed
afterwards. Hope this might help.

Cheers, Don in SOFL.


Maybe you could try coating the stone with clear fingernail polish
before buffing then soak the entire piece in acetone after the
buffing is complete…


Thank you all for your suggestion, I’m trying to test the clear nail
polish to protect the agate but it seems to be not enough resistant
to the buffers abrasion. I’ll try to test the liquid colourless wax
sealing the agate’s pores.

Alberto Ruperti

Ciao Alberto,

I nearly suggested using clear fingernail polish but after writing
my post I realized it probably wouldn’t stand up to the abrasion and
heat of polishing. One thing I’ve used with some success to seal
pores/cavities in stones is sodium silicate, more commonly known as
water glass. It’s a liquid that hardens on exposure to air but is
water-soluble and will dissolve when soaked for a day or two. It was
widely used here when refrigeration wasn’t widely available to
preserve eggs by sealing the shells and preventing air from
penetrating. It might be worth a try if other attempts fail.

Rick Martin