Re: possible answer to archivalness comparison between carbon gum andpt/pd

[Sandy King <sanking@clemson.edu>]

Shadow values of 2mm above the substrate is awfully high. I have 
never seen a carbon print with anywhere near that much relief. My own 
prints, even with my high relief tissue, tend to have no more than 
about .2mm of shadow relief over the substrate. But even this amount 
can be rather spectacular on some substrates.

The B&S commercial carbon tissue is not very thick. It is hard to 
measure the exact value but I would estimate that shadow value over 
substrate is about 0.04mm.

Sandy King







At 2:36 AM -0500 3/2/08, etienne garbaux wrote:
> Sandy wrote:
>
> > I am currently making a very thick carbon tissue (weight height of 
> > about 1mm) for negatives with a log density range of about 2.7. 
> > With the correct sensitizer
> > this tissue is capable of prints with great relief. I push the 
> > envelope on this since relief is one of the most distinctive 
> > characteristics of a carbon print.
> Some of the 19th century examples I have, and others of that era I 
> have seen, have deepest shadows around 0.075" (nearly 2 mm) above 
> the substrate.  Around 0.035" to 0.050" seems more typical in that 
> era, and some are only 0.020" or 0.030".  The alt-carbon prints I've 
> seen in the last 15 years or so appear to have less than 0.010" of 
> relief, but I haven't been in a position to measure one accurately. 
> Some commercial tissue I was shown recently looked to have less than 
> 0.020" of gelatin (again, eyeballed, not measured).
>
> I'm ambivalent about the relief -- as I mentioned, I find it 
> distracting if the lighting allows for any specular reflections or 
> shadows of the relief from low-incidence light.  I have always 
> believed that the best tonality is achieved by mapping the scene 
> values to the most extended negative values you can obtain, then 
> using a low-contrast printing medium to suit the negative.  (I think 
> this is true for pretty much any full-tonal-range medium -- 
> certainly carbon, Pt, kalli, and cyano in my experience).  So, I 
> favor fairly thick tissue, but not because it makes prints with lots 
> of relief.  I actually stopped making carbon prints for a time after 
> I started making monochrome dye transfer prints, which have a very 
> similar tonality but no relief in the finished print.
>
> Best regards,
>
> etienne