Digital BW, The Print

Clayton wrote:

> Maybe you can answer some other questions that I've had for some
> months.  There are other ink based arts that have existed for a long
> time, including silk screen, etching, and photogravure to name a few.
>  Are these processes considered "archival"?  How long have these art
> works lasted?  What kind of inks and papers have been used?  I
> recently saw an auction listing where some original Edward S. Curtis
> photogravures sold for big bucks.  It's probably safe to assume they
> haven't faded, and they must be approaching 100 years now.  What kind
> of ink and paper were used for them?

The printing processes are not archival if the components are not 
archival themselves. Paper quality (especially buffering), ink 
(pigment quality mainly but also the binder + drying process), 
ink layer thickness and care in the printing process (water 
quality used in the stone printing). I've seen enough silkscreen 
prints that lost their color partly while that process often is 
chosen for its quality to get color and keep it. Silkscreen is 
one of the few  technics that can be used with a variety of ink 
binders: water based acrylics (+styrenes), urethane, solvent 
based cellulose, vinyls, acrylics, two component epoxies, UV 
curing acrylics, polyesters and the old oxidising linseed, alkyd 
varnishes etc. Combine that with cheap or expensive pigments, 
multi color spot printing in thick layers or full colour with 
fine mesh screens and you get a whole variety of archival qualities.

Intaglio printing itself has been around since the early 15th 
century, metal engraving was already used for armory before that. 
Wood cuts followed by wood engraving existed before intaglio and 
the inks used for that printing technique where not that 
different to the intaglio inks (and the inks later used for litho 
or even the first silkscreen inks). In fact they are quite 
similar to oil painting materials (usually credited to Jan van 
Eyck, early 15th century too). Carbon (lamp) black, mineral 
pigments and a variety of oils that will oxidise to the air as 
the binder (often aided by a catalyser) and so hardened protect 
the already excellent mineral pigments to humidity etc better 
than the water based binders of inkjet. Don't expect the gamut of 
the modern pigments or dyes. The whole idea of tri color 
subtractive mixing didn't exist before the 18th century. The 
mineral pigments themselves are much older and have been used 
with wax or eggwhite binders before that. For wax paintings on 
walls you have to think in two millenniums. Some cave temples in 
Libanon if I'm not mistaken. Binders for the even older cave 
paintings were based on fat I believe.
Photogravures date back to 1860 I guess, like many of the 
printing techniques that were invented to illustrate the books 
and magazines printed in large quantities already. Collotype a 
bit later. There's a nice small book on Victorian book 
illustration technics upstairs but its almost bedtime here :-). 
Most problematic part of all the prints of that time is the 
paper. With the rising demand for printing paper other bleaching 
and sizing technics were introduced that showed their bad 
archival qualities later.
But on a good textile fiber paper a 500 year old woodcut will 
exist for another 500 years in the museum climate they are most 
likely in now. There's a paper manufacturer in Scotland (Tullis 
?) that makes a paper for expensive books based on alpha 
cellulose and they claim a 500 year age if properly archived.

The Curtis gravures are not that uniform in their quality 
(different printruns in time) if I remember it correctly but I'm 
no expert on that subject. Density loss will be no problem given 
the color. Sometimes there's binder bleeding in the paper with 
photogravure when the binder doesn't harden fast enough. Mold can 
always appear on paper in bad archival conditions.
Oil based binders have a tendency to yellow unlike acrylics so it 
certainly isn't so that all what is old is better.

Ernst