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Subject: Cleaning stone

Cleaning stone

From: Robert Lodge <mckaylodge>
Date: Monday, September 24, 2001
Tony Sigel <asigel [at] fas__harvard__edu> writes

>In Cons DistList 15:23, Robert Lodge writes:
>>For cleaning building or sculpture stone when high pressure water
>>alone (hot or cold) is not effective, I recommend the JOS system. In
>>skilled hands it can even be safely used to remove dirt from painted
>>exterior surfaces.  We use the system for cleaning a variety of
>>materials.  Its use is growing in the United States.
>What, exactly, is the "JOS" system? Could one of the people who have
>mentioned it explain, and in the future could proprietary or trade
>name usage be accompanied by a description, list of constituent
>materials, etc?

What the possible acronym "JOS" actually stands for does not appear
to me to be identified in the Canadian, U.S. or German product
literature. However, these sources strike me as being rather weak in
information and containing some questionable physics.  The cleaning
system using a proprietary abrasive/water-injection nozzle is always
in the literature simply called "JOS System".

Even a study of the tool by the Institut Royal du Patrimoine
Artistique (93/5223) identifies the system only as "JOS."  I did not
burden my response in Con DistList 15:23 to a inquiry in the
previous Instance about cleaning stone with details about the tool
and materials. Instead, I provided four (4) web site sources of
information; one of which, a section of
<URL:>, provides details of its application
in cleaning bronze while another is the site of the German inventor
and his company.

JOS simply uses a proprietary nozzle which mixes compressed air and
powdered glass (or other abrasives, sometimes dolomite) @ 40 psi
with water entering @1000 psi. We tested in its place a common U.S.
water injection nozzle, Boride's WIN nozzle, and got results and
control similar, but not as good in some applications, to that of
the JOS nozzle.  The general technique of incorporating water with
air/abrasive is common and is usually called "slurry blasting."
However, there are variations and the JOS system is the "open
nozzle" system (see Journal of Protective Coatings and Linings, Vol.
18, no. 9, Sept. 2001, 877-281-7772).   Please feel free to contact
me for other information from the perspective of a user.

Robert Lodge
Mckay Lodge Conservation Laboratory, Inc.

                  Conservation DistList Instance 15:26
               Distributed: Wednesday, September 26, 2001
                       Message Id: cdl-15-26-004
Received on Monday, 24 September, 2001

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