RE: Infrared in questioned documents

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

>From: Roque
>To: infrared
>Subject: Infrared in questioned documents
>Date: Monday, November 29, 1999 2:04AM
>
>Hi,
>I live in Brazil and I am beginning a work of analysis of questioned
>documents.
>I will use a Digital Back Phase One in a Hasselblad. I need to decide which
>filter for infrared should buy (here the filters are very expensive), and I
>would like to know which is the filter more adapted for this work type. If
>somebody has experience with analysis of documents it helps me. Should it
be
>Wratten 88A or Wratten 87C?
>Thank you,
>Roque Boeira
>roqnet@xxxxxxxxxx

Roque,

You will find that the 87C will give more of the effect you are looking for.
I am unsure what your Digital back will be able to record in the IR
spectrum, but the 'stronger' you IR image the better to show the difference
between visable reflectance and IR reflectance.  Here we use a 87c with the
now no longer made  Kodak HSI to record these differences.

Email me if you would like further information.

I also presume you will be looking at the documents under UV light as well ?

Jason Revell
Conservation of fine art
Univ. of Northumbria
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