Demachy and Maskell's postscript

As you know, I don't usually spend much time reading historical
literature about gum printing or trying to replicate old techniques,
because I've never seen much useful information come out of such
investigations. (Not to denigrate those who do enjoy this kind of work,
but only to say it's not for me).

But in a private correspondence with a chemist who knows some things
about some other processes but zero about gum printing, (maybe I should
specify that this is no one on this list) he appealed to the method
outlined in the Demachy postscript to support a point he was making, and
asked hadn't I ever tried that. I hadn't, and didn't figure I could say
anything about it without having tried it, although now that I think
about it, his not having tried it himself didn't keep him from having an
opinion about its usefulness to the discussion. But I digress.

So, I tried it, with spectacular lack of success. For those not familiar
with this, Demachy was recommending soaking the paper in potassium
dichromate, drying it bone dry, then coating with gum and pigment, with
some water added to make it spreadable. He claimed this two-part
emulsion eliminated stain and what's more was 4 or 5 times faster than
the pre-mixed emulsion.

I tried it four times, with four different papers. Each time, I not only
got pigment stain with my usual amount of pigment, but dreadful brown
dichromate stain; I never get either with my usual practice. What's
more, the two-part emulsion, if anything, was slower than the mixed
emulsion, contrary to the claims in the article.

So, I'm curious. Has anyone ever tried this and got better results? The
fact that this method has not survived or been revived by gum
revivalists over the decades suggests to me that I'm not the only one
who hasn't been able to make it work, but if someone has I'd be
interested in hearing about it.

I know that one argument when one can't replicate old techniques is that
the papers and stuff were different then. But I have a hard time
imagining how a different paper would print four times faster if it were
soaked in dichromate first-- what that paper would have to be like for
that to be the case.

If anyone's interested, I'll be glad to scan test prints to look at.

Katharine Thayer
Received on Sat Apr 9 15:14:37 2005