Re: Autoclaving gum and gelatin

From: Katharine Thayer ^lt;>
Date: 02/08/05-04:18:07 AM Z
Message-id: <>

For crying out loud, this is making my teeth hurt, and I haven't even
read half of this stuff.

I will say this: I'm utterly and decidedly fed up with people who know
nothing at all about gum printing telling gum printers how gum printing
works, based on theory that may or may not be applicable to the case in

For one example, there was a terrible row last summer when some guy who
knew about commercial printing inks but nothing at all about the
pigments used in gum printing, generalized his color theory to a place
where it doesn't belong and was determined to shout me down when I said
that you can make black in tricolor gum using three colors. He said no
you can't, and he was not going to give up until I agreed with him, but
unfortunately for his purpose this is something I know so thoroughly
from experience that there was no way to make me question my "own lyin'
eyes." Yes, you can make black with three colors, I do it all the time.
His inability to force me to agree with him made him so angry that he
told me, in a roundabout but unmistakable way, to do something to myself
that is unprintable here, and stormed off. Later, someone accused me of
having run people off the list with my observations about CMYK; this is
the only person I know of who actually left because of that, and I say
good riddance to him.

A while back Sandy was going on about his disgust at people who chime in
on a thread whether they know anything about it or not; I must say I am
in complete agreement with him on this.

I thought we had settled this the last time around, but I'll review for
clarity what I thought was decided: Kate, Judy, I and perhaps others,
all reported that we have observed that if the gelatin gets "too hot"
then it doesn't work well as a size for gum. I don't know the cutoff
temperature between "too hot" and "not too hot" but I just heat the
gelatin enough to dissolve completely and to stay melted while brushing
on, which doesn't have to be over 120F, and it works fine. If it does
get too hot, it results in a characteristic speckling pattern, as Judy
said, and as I and others have also observed. My information comes not
from old literature, which I don't read and didn't know that it said
anything about this, but from my own experience.

In that earlier thread, I said "I'm not sure it matters what happens
technically to the gelatin; what is important is that overheating the
gelatin seems to lead to imperfect sizing, for whatever reason." I
still stand by that statement. But I'm not arguing that the gelatin
loses its ability to gel, or that it otherwise "breaks down," only that
something happens to its ability to provide an adequate size for gum. I
won't say what that is, because I don't know, but it doesn't really
matter what causes it physically or chemically, the fact is that this is
what happens, at least in my shop. But what the heck, the guy should
just autoclave his gelatin and try using it for a sizing for gum, and
see what happens; the more information the better.

As I said, it's been my observation that when the gelatin is overheated,
the sizing fails and results in speckling. That observation isn't
altered by all the arguing and bloviating about gelatin and its
different states and the ability to make calves foot jelly by boiling
calves feet. All those things are no doubt true, but still, if you get
the gelatin too hot, the resulting size will give you speckling in your
gum print. At least that's what I've observed a couple of times, and I
found that lowering the temperature of the gelatin took care of the
problem. In social science research we call this a single-subject ABAB
research design; it is a good design for a situation like we've got in
gum printing where the "tests" that are done can only be done one gum
printer at a time. If you see a particular result under one condition,
and you don't see the result without the condition, and if this pattern
is repeated, where every time you see the result, the condition is
present, and when you remove the condition the result goes away, it's
fair to assume that you've learned something.

For both Judy and myself, it looks like we've learned that for our own
case, it was the heat that made the speckling. But whether this only
applies to glyoxal-hardened and unhardened gelatin, or only in our own
particular labs, one can't say, and I don't think either of us are
saying. What I've said is that this is my experience, use it if it's
useful to you. But to hoot the observations out of existence simply
because they are inconsistent with some theory of how gelatin behaves,
is itself inconsistent with being a scientist. Scientists rely on
observations; if the observations don't agree with the theory, they
adjust the theory to reflect the reality of the observations, rather
than dismissing the observations out of hand. When at least three people
have observed that hotter gelatin results in sizing failure for gum, and
that using a lower temperature eliminates the speckling, then it seems
outrageous to me to be so derisive about those observations.

As to the ruckus below about Judy's inconsistency, it makes no sense to
me. The way I read it, Judy was saying that this speckling had never
occurred before the incidents of overheating; in other words, that the
only cause for this speckling she could see was the overheating of the
gelatin. This seems a reasonable inference to me, since she saw it more
than once. To make something else out of it seems like someone is going
out of their way to be argumentative and derisive to the point that they
are making up sutpidities in others' posts that aren't even there to an
objective observer.

It seems to me also that the derision is selective as to whom it's
directed at; other gum printers make sweeping statements from much less
evidence all the time, without being treated to this kind of insulting
condescension and derision.

While I'm at it I'll just touch on the subject of adhesion, which is
another of these cases where knowledge in one field doesn't necessarily
explain what happens in another field. It is my experience that in gum
printing, adhesion is about tooth, about the physical characteristics of
the substrate; the principles of adhesion that adhere glue and paint to
their substrates aren't terribly relevant. I have demonstrated to myself
too many times that the same material that won't hold the gum by itself,
will hold it well if roughed up, or if inert material providing tooth is
added to it. It may be that the other principle also holds, but if so I
expect it holds to a lesser extent, for practical purposes, than the
principle of tooth. But tell you what. I am printing gum on glass using
only the principle of tooth. When you've printed gum on glass using only
the principle of adhesion, with no appeal to the principle of tooth,
then we can have a discussion. But hooting about stuff that you've never
done yourself is just annoying and not very helpful.

Now, if someone could help me figure out where the light leak in my new
pinhole camera is coming from, which has been making me tear my hair out
for two days, I'd be in business.
Katharine Thayer

Ryuji Suzuki wrote:
> From: Judy Seigel <>
> Subject: Re: Autoclaving gum and gelatin
> Date: Tue, 08 Feb 2005 02:26:55 -0500 (EST)
> > I prefer to simply warn them (and others) about heating the gelatin
> > above 140 F. Something along the lines of my earlier exegesis Ryuji
> > so kindly posted today. I have found that, barring inattention and
> > hexed hot & cold water lines, it generally does the trick.
> Huh? I requested you to explain your statement that heating gelatin
> above 140F "breaking down" the gelatin never happened before. After a
> couple of months, all of sudden, gelatin heated above 140F now "breaks
> down" and you argue you gained this knowledge through 14 years of
> teaching experience. How convenient.
> Practicing such a greatly mystifiable gum dichromate process does not
> make you immune from criticism when making a wild argument out of
> casual observations from such sloppily controlled trials. It is
> especially so when the argument is inconsistent with existing
> knowledge in chemistry literature, and when the argument is
> inconsistent with the earlier statement of your own with no good
> explanation.
> --
> Ryuji Suzuki
> "Well, believing is all right, just don't let the wrong people know
> what it's all about." (Bob Dylan, Need a Woman, 1982)
Received on Tue Feb 8 12:14:22 2005

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