Cleaning wooden doors

M. Susan Barger <barger [at] unm__edu>, on behalf of a colleague, writes

>    What is the best way to clean exterior wooden doors? These doors
>    are coated with the grime of use and exposure to the elements.
>    The exposure includes bird droppings. The doors may have been
>    painted or varnished at one time, but there is little evidence
>    of that now--they are approximately 400 years old and exist in
>    rather harsh conditions...

I cleaned a set of 17th or 18th century Castle doors by making up a
1:9 water to industrial methylated spirit (Industrial methylated
spirit (95% ethanol, 5% methanol) in Klucel G, to produce a gel.
This was applied to the (now horizontal) door surface, covered with
Cling film or a polythene sheet, and left for 2 -3 hours This was
then gently scrubbed with a variety of brushes, as appropriate, and
then with 3M scouring pads, green or white variety, on the flat
areas. All scrubbing and brushing to be done with the minimal
effective force; the gel may need to be re-applied. Small areas were
treated at a time, about 1 -2 foot square, otherwise it dries out in
situ before the soiling can be removed.

The gel is then scraped off with polypropylene spatulas, gathered
into sealed bins, and the surface washed down with IMS and soft
brushes.

Use minimal force at all times: the doors we worked on had a huge
number of graffiti scratched into the wood (from the Napoleonic War
period and earlier) and we were particularly concerned not to raise
the grain, which would have disrupted the images. We (and our
clients) were very pleased with the results; so much so that they
were intending to build a display around them, instead of simply
placing them back in the wall.

Do not increase the water content, or the grain will be raised. We
found that this worked very well without any water at all, leaving
the grain totally unaffected, but as always, try a small section
first; it depends on your type of soiling! The material we removed
appeared to be largely soot. You do need to leave the gel in place
for at least 2 hours.

Appropriate health and safety measures must be taken eg good
ventilation, air extraction, goggles and mask, spark-free working
area. Great care must be taken with exposure to the bird droppings,
as these can cause many health problems. It may be advisable to seek
advice on disposal of the materials used in cleaning the doors--you
may be advised to allow the solvent to evaporate safely, then burn
all the contaminated paper, etc in a locally approved area/fashion.

Mandy Clydesdale
email mandyc [at] aocscot__co__uk
AOC Archaeology, The Schoolhouse
4 Lochend Road, Edinburgh EH6 8BR
+44 131 555 4425
Fax: +44 131 555 4426

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                  Conservation DistList Instance 13:23
                 Distributed: Tuesday, October 5, 1999
                       Message Id: cdl-13-23-002
                                  ***