Grease stain on paper

Artemis BonaDea <paradux<-a t->alaska< . >net> writes

>I have been contacted by a customer who has recently (within the
>last week) stained a book with a ginger snap cookie.  She laid the
>cookie down on a page of a facsimile copy ...
>I am looking for information on removing the grease stain, which I
>would assume was butter or cooking oil.

I would like to suggest the possible use of the enzyme Lipase. I
carried out some research into the use of Lipase for stain removal
in 1993 and tested it on a variety of different fats and oils
ranging from Linseed oil through to animal fat. Unfortunately my
research did not include butter, but it did include tests on
sunflower oil. My results showed that the stains from non drying
oils could be visibly reduced. However, my experiments were limited
and I was unable to show the precise amount of fatty acid remaining
in the paper after treatment.

There are some practical problems with the use of Lipase which may
prevent you from using it on your object.

Firstly, stain removal has too be carried out in warm conditions for
reasonably quick results. The optimum temperature for type vii is 37
degrees Celsius. If you enzyme is applied locally, then there should
be some method of keeping the area warm for at least half an hour.
It is also worth considering whether you would be able to
effectively remove your enzyme from the substrate when the treatment
is complete. Lipase is denatured at high temperatures, so your
substrate would have to be able to withstand a wash in water above
seventy degrees celsius to remove the enzyme (and the carrier if you
decide to use a poultice method of application). This may be
possible if you have the use of a suction point.

The usual health and safety  precautions should be taken when using
Lipase in conservation. If the enzyme is in desiccated form then
solutions should be mixed in a biological safety cabinet while
wearing gloves.

Fresh oil stains respond better to treatment than aged ones. I
noticed that in the case of highly coloured stains,  opacity of the
substrate could be restored after treatment, but sometimes the
colour remained.

I hope this information may be of some use, either practically or
academically.

Vanessa Charles
Conservation Assistant
Library Conservation Unit
University of Dundee
DD1 4HN

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                  Conservation DistList Instance 10:84
                  Distributed: Friday, March 28, 1997
                       Message Id: cdl-10-84-007
                                  ***