Stains on marble

Martin Cooper <martin.cooper [at] liverpoolmuseums__org__uk> writes

>Andrew Thorn <artcare [at] iprimus__com__au> writes
>
>>Eric Miller <eric.g.miller [at] btinternet__com> writes
>>
>>>We are currently cleaning a marble fireplace that has yellow/brown
>>>tar stains that do not respond to our attempts at removal. Laser
>>>cleaning works but it turns the marble yellow. ...
>
>I'd like to make two comments:
>
>(1) If a process 'turns the marble yellow' I would suggest that it
>does not 'work' in this instance. ...
>words we use. Laser cleaning is no different from any other cleaning
>technique in that it has to be used appropriately; it works very
>well in some situations and not so well in others. If a test clean
>shows negative results then the technique does not 'work' and, of
>course, should not be used.
>...
>... Training courses are also available for
>conservators wishing to learn more about the technique and wanting
>to gain some practical experience. ...

Martin never misses a trick to plug his course. That's
OK--especially in the current climate. Others may wish to know that
I have also received useful suggestions--which we are keeping for
trial later. We're not actually using the laser Martin; it 'turned
the marble yellow'--on test. Progress report: The fireplace is 18th
century much of which is stained yellow/brown by smoke. This stain
is coming off with 5% tri-ammonium citrate in paper pulp poultices
with 5 minute dwell-times. The intractable stains are ingrained,
cigar-butt-shaped on the hearth-stone, which is severely eroded.

Eric Miller


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                  Conservation DistList Instance 22:54
                 Distributed: Wednesday, March 25, 2009
                       Message Id: cdl-22-54-008
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