If it is caliche (carbonate buildup) then mild acid should dissolve it. Perhaps an aqueous solution of 5% Hydrogen Chloride solution (HCl available as muriatic acid in concentrations around 35% from hardware stores - use eye and hand protection and good ventilation. Add acid to water to dilute not vice versa). Try a small spot of acid on the surface first. If it is going to do anything useful you will observe effervescence. Downside is that the acid will also attack any free iron but provided the acid is weak any carbonate should be dissolved away much quicker. Once any application of acid is complete the stone will need to be thoroughly rinsed and dried. Hcl is a gas at normal temperatures so should evaporate away with the water when it dries. I wouldn't try this with anything I was extremely fond of. Ideally you have another less precious stone from the same area with the same surface deposit that can be experimented on.
Regards, John On 11/12/2012 16:30, "bill kies" <[email protected]> wrote: > >Desert varnish in itself shouldn't obscure flow lines. He must mean >caliche. > >---------------------------------------- >> Date: Tue, 11 Dec 2012 10:57:34 -0600 >> From: [email protected] >> To: [email protected] >> Subject: [meteorite-list] how do you get off desert varnish from a >>oriented stone? >> >> Hi list. I have a real nice 31 gram oriented stone that has desert >> varnish on one side. It has very nice flow lines under it that I would >> like to see more of. Can someone please tell me how to that varnish >> off. Thanks and have a great day. >> >> -- >> Steve R. Anold, chicago, ill. >> ______________________________________________ >> >> Visit the Archives at http://www.meteorite-list-archives.com >> Meteorite-list mailing list >> [email protected] >> http://six.pairlist.net/mailman/listinfo/meteorite-list >> >______________________________________________ > >Visit the Archives at http://www.meteorite-list-archives.com >Meteorite-list mailing list >[email protected] >http://six.pairlist.net/mailman/listinfo/meteorite-list > ______________________________________________ Visit the Archives at http://www.meteorite-list-archives.com Meteorite-list mailing list [email protected] http://six.pairlist.net/mailman/listinfo/meteorite-list
