How can I mask white spots in pink marble?

[Don Dougan <dondougan@zzzzzzzz>]

Hi Michiel;

I have worked a number of pieces in Georgia Etowah pink which can be very
similar to the Portuguese pink marble -- and I have had the same problem
of trying to remove bruises that were to deep to remove without changing
the contours drastically.

One solution I used was full strength muriatic acid applied to the
bruises to etch the damaged crystalline structure away.  The entire stone
was first rinsed in water, then I used a natural-bristle brush to apply
the acid to the bruises.  On two or three 1centimeter or half-inch deep
bruises It took an hour or more of constantly reapplying acid and
periodically rinsing the surface to prevent the acid from eating away
non-bruised areas.  The end result did leave depressed areas where the
bruises had been, but there was no distracting surface discoloration.

In other words, take your choice: bruises or dimples.

I know it is not what you hoped to hear, but other than carving and
fitting 'patches' of stone to match the existing contour, I don't know of
any other way to retain the contour and get rid of the bruises (more
recent solutions for similar problems have meant changing the carved
contour design so as to adapt to the stone's flaws).

Good Carving to You;
Don

http://www.dondougan.homestead.com/indexdd.html