Re: (Fwd) Infrared Photographer wanted

["Jason Revell (in5)" <jason.revell@xxxxxxxxx>]

How well the IR photograph depends on what was used to make the
signature.

If the pigment used to make the signature contained carbon there would
be a good chance that the photograph will make the signature appear
much darker.  This is caused by the fact the carbon absorbs IR light, so
none is reflected onto the film.  The handles being made from
ivory should also help as that reflects a good amount of IR light, so
you will be looking at a dark signature on a light background.  Also
as the ivory probably slightly porous the pigment may well of been
absorbed into the ivory making that part of the ivory absorb IR light.

The problem though is the fact some other pigments actually reflect
IR light or become transparent.  The most commonly used round the
turn of the century was Iron Gall ink.  This becomes lighter when
photographed under IR, so it would actually make the signature
disappear rather than appear, (one of the most used inks of today,
biro ink becomes totally transparent under IR).  Iron Gall ink does
darken under UV light though so the solution in this case would be to
take the photograph under UV light.

So what I would recommend would be to take a photograph under IR and
see what shows up.  If however this shows up nothing, not give up as
the pigment used could well show light on the grips.  If this were the
case
try taking a UV picture and that might help.

I hope this helps, If you would like any further help with this type of
photography
(IR or UV) please let me know, as teach the Photography to Fine Art
Conservation students using these very methods.

Jason Revell
Jason.Revell@xxxxxxxxx
 ----------
> I am looking for a photographer that can shoot some infa red pictures
of an
> antique pistol with ivory grips.  The grips have a signature in them
that is
> no
> longer  visible that I would like to "bring out".  The Smithsonian
Institute
> has
> recomended infa red photography to me.  Can you help?

I'd guess that the signature was carved into the grip?  If so, there may
be several techniques to try and bring this out that wouln't
necessarilly
require IR photography.  I think more information is needed, otherwise
the
results might be a bit disapointing.


 - Wayde
  (wallen@xxxxxxxxxxxxxxxx)
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