Beau,

This one is a can of worms - but really shouldn't be!  For at least the last 
40 or more years, every museum conservation laboratory and art conservation 
graduate program has been stressing that oils of any kind are BAD for 
historic or museum objects.  Why does this question keep coming up?  For 
several reasons.  1) Oils were used traditionally to fabricate objects, e.g. 
oil paint and oil furniture finishes.  2) Oil is quick, cheap, and easy. 
Just rub it on and rub it off.  Other materials/methods require more 
knowledge and skill.  3) Marketing dollars - remember Homer Formby?  Also, 
all of the Pledge ads (it contains silicones, another issue that is 
anti-preservation).  4) Craftsmen have romanticized the visual effect of oil 
finishes.  Many still use these materials in their manufacturing processes, 
and recommend them as a maintenance procedure.

The critical distinction here is preservation of a cultural artifact for 
centuries, millennia, or longer.  What you can do on the family farm to keep 
the plow blades from rusting until the next season (coat with oil) is vastly 
different.  Oiling that Danish modern dining table annually may be fine for 
a generation, but it will create problems in the longer-term.  Throw out all 
of those "old wives tales" or "home-brew remedies" when it comes to 
preservation of museum collections (or preservation of any historic object, 
for that matter - I don't want to get into the debate about private owners 
having the right to destroy collections that they own).

So, for simplicity's sake, a really quick primer on oils.  Oils are of two 
types, drying oils (react with oxygen to polymerize) and non-drying oils. 
Drying oils such as linseed, tung, and walnut initially polymerize (form 
chemical bonds across smaller molecules, aka cross-link) to form a large 
molecule as part of the conversion from liquid to solid.  However, this 
process continues with time/aging, with these oils becoming ever more 
insoluble, while at the same time darkening.  In the presence of acids and 
other components, they can become black and completely obscure the 
underlying surfaces.  Non-drying oils, such as mineral oil, lemon oil, and 
lubricating oil don't dry and remain essentially liquid, creating a gummy 
mess over time as they combine with dust/dirt which are attracted to them. 
Neither of these can be easy to remove from affected surfaces in the future, 
and can require hundreds or thousands of hours of conservation effort.  In 
some cases, it is impossible to remove them from more delicate underlying 
paints and finishes.

In summary, NEVER use oils with museum collections.  Of course, there are 
always exceptions, such as lubricating oils for an operating piece of 
equipment, like an engine, but only if it is actually in use (another 
Pandora's box that does not need to be opened).

The following link from the Smithsonian Institution (same division I used to 
work for, but it now has a different name) talks in great detail about 
furniture coatings/finishes, and buried within is information on oils.

http://www.si.edu/mci/english/learn_more/taking_care/coatings.html

Marc

American Conservation Consortium, Ltd.
     4 Rockville Road
     Broad Brook, CT 06016
     www.conservator.com
     860-386-6058

*Collections Preservation Consultation
*Conservation Assessments & Surveys
*Environmental Monitoring & Low-Tech Control
*Moisture Management Solutions
*Collections in Historic Structures
*Collections Care Grant Preparation
*Conservation Treatment of:
     Furniture
     Painted Wood
     Horse-Drawn Vehicles
     Architectural Interiors

Marc A. Williams, President
     MS in Art Conservation, Winterthur Museum Program
     Former Chief Wooden Object Conservator, Smithsonian Institution
     Fellow, American Institute for Conservation (AIC)


----- Original Message ----- 
From: "George Harris" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, November 28, 2007 8:54 AM
Subject: [MUSEUM-L] Oiling objects


Hi,
Thanks for the great packing advice.  My next question is about oiling
objects.  In my training, experience, education, and what makes sense to
me is that no oil should be used on any objects in the museum's permenant
collections, period.  My boss, the director of collections, suggested it
the other day and I suspect may still want to put something on, she also
suggested vasilene, which I would also not use on anything.  My question
is are there any oils (or is vasilene) that would be acceptable to use on
any museum objects ever?  If so, what are they and does anyone know where
to get them and how much they might cost?  If not, can anyone suggest any
resources, including online, where it says that you shouldn't use oil?  If
it gives reasons for not, that would be good too.

Beau

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