>Message text written by Judy Seigel
>>
>Terry,
>I'm disapppointed that, in your usual eagerness to correct me,
I was not trying to correct you. I was just pointing out that there is
more than one approach. That becomes more clear each day from what we
learn of other peoples' practice on this list.
> you overlook the original puzzle: why my friend's exposures were so slow.
>Most of your annotations were thus not much help
I had already commented, I think last week, on a very similar problem.
> -- although they did
>repeat material we have been over in the past year, for those who are new
>and don't want to bother going to the archive.
True but we were both reploughing the land.
>However (also as usual),
>while I can see that you're trying to be helpful, you have "corrected"
>quite a few things I never said,
But Judy as you yourself have often pointed out, comments that arise can be
of more general application that a specific reply to a specific point.
> ie., put words in my mouth, such as:
I hope you will see that I had no intention of doing so.
>On Mon, 27 Jan 1997, Terry King wrote:
>
>> For multi colour printing I remain unconvinced that using a step wedge
>> tells you anything at all.
>I have not recommended the step wedge for a multi color print, tho even
>there some of its information may be relevant.
As at least one of us is an old timer in the world of gum I think that we
both appreciate that it is not necessarily clear, to the relatively
inexperienced, that practice in making single colour gums from a single
coat differs from that in making multi coated gums. For the single coat one
needs different coating techniques and different strenghts of pigment and
even different negatives.
> But I note again that
>especially with issues of this sort (puzzles!) no other indicator can
>compare.
There is an aternative approach that can give more information, in the
context of the multicolour print, and that is making a work print stage by
stage in advance of making the final print. For a single coat I am sure
that you are right.
Incidentally have you tried indian ink as the pigment for single coated
gums.
> I'll also add that the kind of quantification thus obtained does
>seem lacking from many of your observations. ("Better" is not
>information.)
Where one is overlaying different colours of differing gradations in
multicolour printing I think that a step wedge can be a hindrance rather
than a help. But in general I now regard the step wedge as being such an
important tool that I find that I always carry one in my American cords
pockets, ( which can hold a reasonable amount of clutter without one having
to carry a purse) together with a collapsible rule and an Olympus Mju
camera.
>> Just remember that the higher the reflectivity of the pigment, > the
>>more you will need. So use strong colours to reduce the amount of
>>pigment required.>
>I'm trying to figure out what you mean by "reflectivity of the pigment"
>(refractoriness? density? opacity?). "Reflectivity" is something else.
With the more highly reflective colours, eg yellows, you need more pigment
to get contrast but more pigment decreases the effectiveness of the light.
In general strong pigments, where you need less of it to achieve the same
effect, will be of benefit.
> In any event, your assertion is not entirely true. Pigments that are
>identical visually, and even comparable in covering power, can differ in
>speed if their *chemistry* differs, as it may well (just as gum arabics
>with the same "refractoriness" can have different speeds due to their
>>chemistry). There is also the difference in sensitivity to UV light at
>different points in the spectrum. The 21-step reveals such differences, if
>you're interested.
That is why I recommended standardising one's practice. Following this
precept I have not found the other variables you mention of sufficient
significance to take them into account.
>> >As noted, the first manifestation of over-pigmentation is likely to be
>> >highlights flaking off.
>> Or the shadows.
>Terry if you can print so that your shadows flake off before your
>highlights you will go down in history.....
Actually Judy it is a fairly frequently occurring phenomenon. It tends to
happen more with gum than Gloy though. In my teaching aids portfolio I
have gum and Gloy prints made from 32 step separation step wedges that
show this clearly. I remember showing them to you when I had the real
pleasure of meeting you.
>As for my question about the relative speed of a 10 % solution of K di
>versus a 30% solution of am di, I know you were making a joke when you
>said 10 into 30 goes 3 times, but in case some beginners get confused,
>I'll note that the print is *not* 3 times as fast, and so I wonder if that
>is the correct arithmetic. If anyone else has a suggestion I'd sure like
>to hear it. (Mike Ware has pointed out that in any case, for any % above
>the smallest concentration, there is a surfeit of dichromate ions: ie.,
>the chemistry involved is complex and subtle.)
Yes it was a sort of joke but funnily enough, Gloy/ammonium dichromate
seems to be about three times as fast.as potassium dichromate/gum arabic.
At least it was when I had to scour a town for materials after a college
pleaded that its gum arabic and potassium dichrmate had not been delivered
for my workshop. My demonstration with the, then absolutely new to me,
Gloy/ammonium dichromate grossly over exposed compared with my usual
practice. I had to reduce the exposures to about a third before the
combination would work.
No matter how subtle the chemistry,and it can be very interesting, if it
works, use it.
> Again be consistent . Make up your own gum from a reliable source or use
> Gloy.>
>Again, Terry, I thank you for your well-intentioned advice, but, if I may,
>will note that I find different gums serve different purposes. For
>instance a slow gum is excellent for masking. A low-gloss gum is handy for
>subsequent coats where I don't want a lot of shine. Etc.
One gum seems to work well enough for me. I get different 'surfaces' by
switching between gum and Gloy or between acrylics and water-colour. I did
not understand the reference to masking. This is a subject where I , for
one, would appreciate further details.
>However, Terry, I am extremely gratified that you ratify and even
>approve* my habit of developing at room temperature, saving warm.water for
an extra push ("a very effective approach" you >call it), especially since
you have in the past insisted on warm water, & quite
>recently, as I recall.
My practice has been for years to start with cold water and then gradually
increase the temperature to achieve the necessary results. One recent
addition to the armoury has been the soft spongy dish cloth which is
marvellous for bringing out additional detail.
> (Maybe you're just buttering me up...? )
No need to butter you up. I am sure that many will join me in saying that
you have done, and do, a hell of a lot for alternative processes.
>Whatever, I close on a cheery note (subject to your corrections of
course),
I should be such a chutzpanik !
Terry