Shagreen

Emily Lin <nilylime [at] hotmail__com> writes

>I am a student of the art conservation program at Queen's
>University. I am writing to request sources of shagreen for the
>microscope box that I am treating. The box has a shagreen covering,
>which was dyed green, and much of it has been lost.
>
>In a previous posting on this list, I learned that shagreen consists
>of the untanned skin of sharks, with the placoid scales being
>smoothened and polished.

I did an extensive study of shagreen for my thesis a couple of years
ago and came upon many misconceptions in the process, mainly that
most people automatically assume that the shagreen they have is
shark skin when in fact rayskin is much more common. Even the V&A
managed to mis-label one of their exhibits, so cursory
identification of the various materials can be problematic.

You don't say whether your box covering is sanded flat or is
nodular, or what shape the placoid scales are. It is generally easy
to tell the basic difference between ray and sharkskin: ray has more
rounded scales of varying sizes and shark scales are more regular,
small (generally around 1mm or so across) and diamond shaped. If the
surface is unsanded and the nodules are rounded, the previous
respondent is correct in saying that it can be difficult to tell if
the covering is actually fish leather at all. However, the nodules
of animal leather shagreen usually tend to be fairly uniform and
repetitive in size and shape, whereas those on unsanded rayskin are
very obviously irregular in size and 'mesh' together rather better.
Also, careful microscopic inspection can reveal grain lines, pores
and hair follicles in the surface if the material is animal leather.
Failing this, inspection of the rough edge left where material is
missing can reveal rounded indents where ray scales have detached.
In addition, the nodules of embossed animal shagreen can often be
made to depress slightly where ray shagreen scales are completely
solid.

The reason you are unlikely to find sharkskin which has either not
had the denticles sanded flat or had the scales completely removed
lies in the abrasive quality of the natural skin--indeed, it was
originally used as sandpaper and to cover the boot-soles of shark
fishermen to prevent them slipping on wet and greasy ships decks, so
that gives you an idea. It certainly isn't a material to be used
decoratively in its natural state as a rule, unless it is something
like smoothhound (mustelis canis), which can be used unsanded but
which still has a slightly abrasive quality.

Once you have determined the type of shagreen you have, there are
some suppliers of it, both sanded and unsanded in the case of
rayskin, although they are few and far between. I did find one who
was kind enough to send me a sample card without charge and I can
let you have his details if you would like. I actually found him on
eBay of all places, supplying rayskins for decorative coverings. It
is as well to be aware, in your hunt for replacement shagreen, that
fish skins obtained from some of the more remote tanneries of the
world have very likely have been treated with arsenic to prevent rot
and would need very careful handling.

If you would like to send me a picture of the covering you have, I
would be happy to try and help to identify it.

Ann Walker
Unicorn Conservation and Restoration Studios
Lincoln, UK
+44 7890 373502


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                  Conservation DistList Instance 21:56
                  Distributed: Friday, April 18, 2008
                       Message Id: cdl-21-56-005
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