Acrylic adhesives

This is in response to the Geoffrey Brown/Stephen Koob debate on 3M 4475
Plastic Adhesive.  I phoned 3M Canada and spoke to the technical
representative, David Gentleman (<usmmm6d0 [at] ibmmail__com>, 519-452-6145),
about this product.  He told me that 4475 is a blend of polyurethane and
vinyl acetate, not an acrylic.  He said it had never been an acrylic. He
affirmed that it did turn yellow.

Polyurethane adhesives do have their problems.  Although I have never
tested them, Velson Horie in his book Materials for Conservation
(Butterworths, 1987, p. 165-170) speaks of their instability.  Mr
Gentleman is sending me data sheets and an MSDS.  If anyone is
interested in receiving these, please let me know and I can send them
out.  Mr Gentleman is also available if anyone wants to contact him.

    **** Moderator's comments:   Jane wrote again to add:

    This is a further response to the Geofrrey Brown / Stephen Koob
    debate on 3M 4475 Plastic Adhesive.  I just received the MSDS on the
    product and it states that it contains polyurethane (20-30%), vinyl
    chloride - vinyl acetate polymer (20-30%) and MEK (50-60%).  The
    vinyl chloride is a serious problem.  Vinyl chloride materials are
    not recommended for conservation.

Jane Down
Conservation Scientist
Canadian Conservation Institute
+1 613 998 3721
Fax: +1 613 998 4721

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                  Conservation DistList Instance 8:81
                   Distributed: Sunday, April 2, 1995
                        Message Id: cdl-8-81-006
                                  ***