There is much made, on the websites of various stone cleaning firms, of particular pieces of cleaning equipment. Of late
DOFF and JOS TORQ, both in their own way excellent tools have been extolled as THE answer to all cleaning problems.
Air abrasion (sand-blasting) was similarly lauded in it's day. Such is the ubiquity of Doff and Jos that often they are the only
allowable methods- as if using them will both guarantee a satisfactory level of clean and prevent accident or poor results.
Stone cleaning is a complex business and cannot be reduced to a pair of techniques and expensive equipment. Steam is, after all,
hot water under pressure and JOS for all it's seductive swirling vortex still abrades.
Stone cleaning involves an understanding of the difference between dirt and patina. It demands a thorough understanding of the
different types of soiling that exist on different types of stone in varying environments. Stone cleaning not only demands this
of the consultant or architect but also of the operative. All equipment and techniques can be used badly and each method comes
with it's unique advantages and potential hazards.
I understand and have a broad range of experience in the use of:
ø timed intermittent nebular sprays
ø ammonium carbonate and other poultices
ø micro air abrasion
ø small scale steam cleaning
ø paint removal systems
and, of course,
I have also taught stone cleaning theory at post-graduate level at the University of Bristol