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265415 Thomas Conroy 2018‑03‑13 Re: "Patina" vs. "Crud"
Erik Levin wrote: "...a machinist chest (presuming it isn't... one fashioned by
Maudslay during his apprenticeship), is not worth the trouble to restore, IMHO."
Layers of oily filth coming off on the hands wouldn't be a problem with
Maudslay's chest. If ever a man was obsessive-compulsive....
The conservation orthodoxy is that you start with the gentlest method of
cleaning and get what you can with that before going on to the next roughest.
You can't leave actual dirt in place, not if it endangers the object itself or
could be transferred by someone's hands to another object. Unless, of course,
its something like the Donner Party diaries and papers, which they have in the
Bancroft Library here, from which no-one would dream of cleaning the soot,
grime, water stains, fat, blood... Back to the point, a conservator will use
water (or, actually, damp on a paper towel); then detergent foam; and slowly up
through alcohol to rougher solvents if you actually must. And you re-evaluate
what you are aiming for after each step.
It doesn't always work out that way in practice. I restored a huge late-
Victorian finishing press. 4" square cheeks and 28" long, filthy and with the
wood rough. I went through the water and detergent,and found that no matter how
long I wiped, I still got dirt transferred to the wipe and the wood had a dirty
surface. Went to alcohol, figuring to take off the shellac and the dirt with it.
Things got no better; in fact worse. Then went savage and started using steel
wool instead of paper towels, then started scraping with a wooden scraper. The
alcohol semi-disolved the degraded wood on the surface, and it mixed with dirt
and old finish to form a gloppy viscous mess that looked like diahorrea but
smelled a bit better. Eventually I debrided down to solid wood, planed the
insides of the cheeks where they hold the book, fixed broken parts, and soaked
in linseed oil with mineral spirits. I won't go into the practicalities of
soaking a 4x4x28 balk in BLO. Where I planed the cheeks it was pretty clearly
maple, but the other surfaces were heavily rounded and "organic" in shape, and a
deep brown like old cherry or walnut. The brown color, I could see on the planed
surface, sank in a half an inch, but the wood was solid. It came out beautiful,
but I have never used it. Not once.

I've worked with salvaged chestnut saturated with machine oil (it was part of
the frame of a pen-ruling machine, and had been catching spurts or drips for
decades.)The oil penetrated deeply, and even light scraping left a gummy-feeling
residue on the surface. If I recall correctly I had to plane off about an eighth
of an inch, then had a surface where the oiliness was mild enough that I could
soak the piece in BLO, and the combinationof oils dried sufficiently to make the
wood handleable. Don't count on being able to reduce deep oil stains by rubbing
the surface with solvent, or even with a soak tank. Deep oil may still seep out
over time. BLO is your friend.
Tom Conroy

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