I have a couple of reconstituted marble statues in the garden, one is about
15 years old, the other is about ten years old.

They both have a tendency to develop red patches or 'rashes' at various
points of the surface. I suspect this is due to some form of air-borne
algae settling and taking hold.

Tried cleaning with bleach and soapy water, but this tends to turn the
markings a deep yellow colour. Anybody have any thoughts about a suitable
method of removing the stains?


--
The Wanderer

Have I understood what the other guy is saying?
Have I meant what I said? Have I said what I mean?

The Wanderer wrote:
I have a couple of reconstituted marble statues in the garden, one is about
15 years old, the other is about ten years old.

They both have a tendency to develop red patches or 'rashes' at various
points of the surface. I suspect this is due to some form of air-borne
algae settling and taking hold.


Yes. This is very much what I found on our sandstone.

Tried cleaning with bleach and soapy water, but this tends to turn the
markings a deep yellow colour. Anybody have any thoughts about a suitable
method of removing the stains?

I found that once I had neutralised the leftover HCL with bleach, it
didnt come back. Seems to like acid conditions.

You are very safe with alkalis on marble..acid is a nightmare.

Try caustic as a stronger alternative to bleach, and pressure washing.

In article ,
The Wanderer writes:
I have a couple of reconstituted marble statues in the garden, one is about
15 years old, the other is about ten years old.

They both have a tendency to develop red patches or 'rashes' at various
points of the surface. I suspect this is due to some form of air-borne
algae settling and taking hold.

Lots of marble also contains iron ore, which might be slowly
dissolving out as rust.

Tried cleaning with bleach and soapy water, but this tends to turn the
markings a deep yellow colour. Anybody have any thoughts about a suitable
method of removing the stains?

Phosphoric acid is particularly good at removing rust, but I have
no idea what it will do to marble, which is very sensitive to acids,
so try it somewhere inconspicuous first.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

"The Wanderer" wrote in message
...
I have a couple of reconstituted marble statues in the garden, one is about
15 years old, the other is about ten years old.

They both have a tendency to develop red patches or 'rashes' at various
points of the surface.

You need to contact the Catholic Church.
They'll buy them for a grotto in Lourdes.

--
Ron

The Wanderer wrote:
I have a couple of reconstituted marble statues in the garden, one is
about 15 years old, the other is about ten years old.

They both have a tendency to develop red patches or 'rashes' at various
points of the surface. I suspect this is due to some form of air-borne
algae settling and taking hold.

Tried cleaning with bleach and soapy water, but this tends to turn the
markings a deep yellow colour. Anybody have any thoughts about a suitable
method of removing the stains?


What's happening to this group?

3 whole days have passed and nobody's suggested an angle-grinder.