Acrylic wood sealants

This question concerns wood sealants used to prevent VOC-emissions
but I've included a few general considerations regarding showcases
in case they inspire comment. I've been looking for a wood sealant
for use on wooden showcases intended for use in short-term
exhibitions.

I want to commission wooden showcases from a local joinery firm, and
they will be in contrast to museum-specification metal-framed
showcases made by a specialist showcase supplier. The acrylic
sealant is intended to seal the showcase interiors against
off-gassing volatiles from the wooden case frame; literature I've
seen over the years has recommended products such as Dacrylate
acrylic sealant <URL:http://www.dacrylate.co.uk/>. I've spoken this
week to Dacrylate paints helpdesk and they recommended their product
103-1 Clear acrylic glaze. They said it's often used by museums for
sealing wood sheet products against VOC-leakage, for example sealing
MDF against formaldehyde off-gassing. The tech. specialist however
said that many water-based acrylic glaze / sealants intended as a
wood glaze/sealants will use similar technology and will be
similarly inert and effective as a sealant. Do list members agree
with this? What other products are recommended? Can anyone advise
generically about simple water-based acrylic glazes? What qualities
in the Dacrylate have made that product specifically recommended?

By comparison Last year I commissioned the same local joiner to make
our first batch of these simple table-top wooden showcases and he
suggested a particular product (in this case Johnstone's "Quick Dry
Varnish", <URL:http://www.johnstones-paints.co.uk/>) and I made sure
I spoke to the manufacturer's helpline to check the product out. The
impression/information I received after discussion was that it is a
water-based acrylic with negligible VOCs (the VOCs here being just
water vapour given off in drying). I asked for three layers of the
acrylic resin to be applied, inside and out (the joiner's initial
reaction was to apply more on the outside than inside).

Last year I also purchased 6 museum-specification showcases costing
about GBP 16,000 in total with which we are very pleased. In
contrast to these the 10 wooden table-top cases purchased already
are intended for short-term use perhaps for a week or even one
evening only for example to support a lecture. The cases to be used
in an invigilated situation while accessible by the public. Cost of
10 table-top cases with internal dimensions of about 50 x 85 cm
floor plan and 30 cm height (20 x 33.5 x 12 inches) was about GBP
2,800. We have had to specify purchases to match our budgets.

Other factors I considered when specifying these custom-made wooden
showcases included the type of wood to be used; glazing
specifications; locking system; dimensions of interior and usability
for wheelchair users and other disabled visitors. I found some of
the most useful resources concerning wood and its applicability to
conservation tasks available on the "Conservation Information" /
"Information sur la conservation" section of the Canadian
Conservation Institute's website <URL:http://www.cci-icc.gc.ca/>
Suitable articles are available from the "Conservation Information"
pages after an author search under "Tetreault, Jean". It also proved
much easier than I initially thought to find glazing that not only
meets UK safety standards for public areas (British Standard 6262 or
6206) but that also has anti-bandit qualities (in the UK British
Standard 5544) and which as a side-effect will reduce transmission
of UV light.

If anyone can advise on acrylic wood sealants I'd be grateful. The
joiner wanted to apply a polyurethane varnish initially (more
hard-wearing than acrylic) but as I knew nothing about this and had
little time to find little information and advice on its suitability
I suggested an acrylic instead.

Dominic Wall ACR MIPC Conservator
Suffolk Record Office
Gatacre Rd.
Ipswich IP1 2LQ
+44 1473 584547
+44 1473 584541


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                  Conservation DistList Instance 18:41
                  Distributed: Tuesday, March 8, 2005
                       Message Id: cdl-18-41-007
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