Re: News from Bostick & Sullivan

Richard,
It's very exciting that you would consider making a carbon tissue for
gravure usage.
I don't think you would cut into Auto monopoly to the extent that they would
cease making their product, as it has a very healthy, if small, consumer
base in Europe.

The problem that has been brought up about Autotype's tissue, referred to as
assh*les, is in my opinion, not a fault of Autotype's manufacturing, but
created during the actual process of making a gravure plate, or to a lesser
degree, during the sensitizing of the tissue. What people may be seeing
could be air bells trapped during the ferrotyping of the tissue. Not to be
confused with trapping air during laydown on the copper which results in
visual air tracks (bubbles) in the stencil. These actually don't etch, and
result in white spots on the final print.
But, trapping small amounts of air during ferrotyping create areas of
thinner gelatin, especially with Autotype tissue, due to it's low gelatin
bloom. These thinner areas will etch quicker and finally blow out to form a
"devil".

The "star" like gunshot wounds to the plate viewed after etching were
commonly referred to as "devils" in the Rotogravure industry. They are
almost always prevalent in the shadow areas of the image because those are
etched the longest and this is where the tissue is thinnest. Also, they are
more of a problem when doing actual grain gravure due to the uneven surface
of the plate due to the aquatint resist.

The main reasons they occur are due to:
1, dust contamination in the process of adhering the tissue to the plate
during laydown.
Even the best controlled environment will contain small dust motes which
will get between the tissue and plate during laydown, causing a microscopic
hole in the stencil that will start etching as soon as the plate is immersed
in ferric. This continues for the entire duration of etching resulting in a
creve-like hole.

2. "free" acid contamination of the ferric chloride etching solutions.
This is probably a more prevalent problem facing people doing gravure work
today. The free acid will increase the rate of penetration by softening the
gelatin where it comes in contact, usually at the site of a dust mote, where
the gelatin is thinnest.
Hunt Blue label Roto Iron ferric chloride, still made for whatever exists of
the rotogravure industry today, contains a very small amount of "free" acid,
but it is negligible for most of our gravure applications.
If you are using a ferric chloride other then Roto Iron, you can be assured
it contains much to much free acid that must be neutralized with a solution
of ferris hydroxide.

Both of these problems will at one time or another plague someone doing
gravures. I've had a close look at Autotype tissue before sensitizing and
have never seen any blowouts in the emulsion, though they may indeed exist.
But I believe the two points stated above are a far more common cause of
devils then holes in the tissue from the factory.
I base this on 30 years of using many different tissues and having these
problems intermittently with all of them.
MaGraw Colograph tissue was probably the best controlled and finest tissue
ever produced for photogravure. It went out of business in the mid 80's and
sold it's coating machines and proprietary formulas to the German Carbon
tissue makers Hansfstengle Gmbh. Hansftengle continued to manufacture the
duplicate MaGraw product into the early 90's, when it was forced to shut
it's doors. I purchased 19 rolls of carbon tissue from their last run, and I
can say that the last run they was not particularly consistent in quality!
But, at the time, it was still a better product then Autotype.
My main gripe with Autotype's tissue is the gelatin and pigment ( iron oxide
which is probably not as finely ground as one would like, as opposed to
MaGraw's burnt sienna). The gelatin itself continues to be dubious, a much
lower bloom then what was used in most pigment papers, hence the difference
in temperature (lower) and shorter time (to control swelling and absorption
of the dichromate) in the sensitizing process. It is slimy, course and not
workable above 53 degrees F besides being notoriously thin.
But, at the time being, it is the best pigment paper made for photogravure
by default!
Cheers, Craig Z.

----- Original Message -----
From: "Richard Sullivan" <richsul@earthlink.net>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Saturday, March 06, 2004 2:37 PM
Subject: Re: News from Bostick & Sullivan

> Assuming this means gravure tissue, what is the gripe with what Autotype
> produces? Quality? Price? Would folks be willing to re calibrate to a
> different tissue. It is my understanding that Autotype dearly wants out of
> making it. The risk is if I come out with it and they drop it, I am in a
> pickle as I have then inherited the mantle. There would be no getting out.
>
> I have heard that some batches are plagued with what are in the trade
> termed assh*les, tiny areas that cause asterisk looking pits in the
copper.
> This i got from a couple of gravure printers here in Santa Fe and also in
a
> book on gravure from the 30's. I believe they are caused by small pinhole
> bubbles in the tissue. With this long a history it may just be an endemic
> problem in making the tissue.
>
> Thanks for the comments.
>
> --Dick
>
> At 12:07 PM 3/6/2004, you wrote:
> >I would like to recommend the production of gravure paper. Autotype could
sure
> >use some competition.
> >
> >Jack Reisland
> >
> >Richard Sullivan wrote:
> >
> > >
> > > With the coating machine I am looking at other coated products like
oil
> > > paper, collotype film, albumen, etc. Comments welcome.
>
>
>
Received on Sun Mar 7 08:14:29 2004