Pigma micron pens

Dee A. Stubbs-Lee <dee.stubbs-lee [at] nbm-mnb__ca> writes

>What is the current opinion among conservators on the list about the
>possibility of using the "Pigma Micron" pens (manufactured by
>Sakura) in place of India ink for artifact numbering?

I have been using Pigma pens for years (not for numbering artifacts)
and have found them to be very useful products. In fact, I have
recommended their use in artifact numbering.

After receiving a call from a colleague concerning a 'browning' of a
clear top coat over a Pigma pen number, I contacted the company
concerning the stability of their product with regard to protective
top coats containing acetone or other potent solvents. The VP of
product development told me that there should not be a problem with
Pigma ink reacting to these top coats because the product contained
pigments which, presumably, should remain stable in contact with
these coatings. I couldn't get a clear answer about what, if any,
binding vehicle was used to 'fix' the pigments in place, which, I
should think, is the key question. I suspect they didn't want to
disclose too much proprietary information on their product,
understandably.

I decided to do some testing myself, as Gillian Noseworthy has done
and reported to the DistList. I tested Pigma and India ink on
barrier coatings of B-72 (in acetone) and MSA (mineral spirit
solvable acrylic) clear varnish. The numbers were top-coated with
the same 'varnishes' after a reasonable drying period. In nearly all
cases, the Pigma numbers were affected by both top coats--this
resulted in lighter numbers (part dissolution, apparently) with a
certain amount of streaking in the direction of the brushing, but
never complete removal. I was surprised that the MSA varnish had
this affect since it has a less aggressive solvent--mineral
spirits--which is normally safe for most varnish and paint surfaces.
The India ink was unaffected by either top coat.

It must be pointed out that India Ink, at least Windsor and Newton
brand, contains shellac which likely helps to 'fix' the dried
product and make it more resistant to solvents--alcohol, of course,
may present a problem in a top coating. I have to say that the old
standard, India ink, is a more stable material for artifact
numbering, if protective top coats are used.

Perhaps direct numbering (no barrier coat) is acceptable, or even
preferable, for some types of objects but for general museum
objects--especially those composed of porous materials--a barrier
coating is a good preventive measure. It must be remembered that
museum objects sometimes change ownership during their existence,
the process of which often involves removal of any former catalogue
numbers. Without a barrier coat, permanent inks may be very
difficult or impossible to remove. As far as safety concerns using
these coatings, vapour respirator masks and vapour extraction
systems are available for that purpose.

Richard Fuller
Conservator
Doon Heritage Crossroads
Region of Waterloo
Kitchener, Ontario


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                  Conservation DistList Instance 19:46
                 Distributed: Wednesday, March 22, 2006
                       Message Id: cdl-19-46-005
                                  ***