Paraloid B72

Teresa Lanca <tlanca [at] bn__pt> writes

>I'm having problems with Paraloid B72 mixed with alcohol as a
>fixative for a blue pigment of a book of the 16th century. It seems
>that the pigment loses is natural brightness and turns opaque (it
>seems that have a white film upon the letters of the text). I don't
>know why this happens and what can I use as a substitute (perhaps
>hydroxy methylcellulose?)

When preparing Paraloid B72 mixed with alcohol as a fixative (you
have not specified the concentration--however, I assume you used
3-5% Paraloid B-72) the solution mixture tends to become unclear or
milky. Adding a few drops of acetone or chloroform to the mixture
clears the solution to be transparent. The results of losing natural
brightness and opaqueness, could be because of lack of acetone or
chloroform. You can reverse this effect by using an air-brush filled
only with acetone or chloroform (I use chloroform) and spray the
problem areas until you get rid of the "milky effect". Hope this
will help.

Michael Maggen
Head of paper conservation
The Israel Museum Jerusalem


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                  Conservation DistList Instance 15:38
                Distributed: Tuesday, November 20, 2001
                       Message Id: cdl-15-38-005
                                  ***