Re: Newbie Gum fun Continued
Katherine, I was going to toss my gummed hat in the ring and make this observation about ivory black being transparent. Due to the transparency of ivory black it's what I use when doing gum over platinum/palladium layers and also when I want to pop a tri-color gum with some black.
-Jeremy- On 4/25/07, Katharine Thayer <kthayer@pacifier.com> wrote:
Clarification: My earlier characterization of ivory black wasn't
quite complete:
I actually prefer ivory black to lamp black, because it's a
transparent color while lamp black is quite opaque, and I prefer
transparent pigments to opaque pigments. But when I use it as a
black (as opposed to capitalizing on its brown characteristics as in
the example I showed earlier) I mix blue with it (usually Prussian)
to counteract the warmth and make the greys more neutral, or
sometimes I take it more cool by adding more Prussian beyond the
neutral point, to result in a transparent blue-black.
kt
On Apr 25, 2007, at 7:34 AM, Katharine Thayer wrote:
> On Apr 23, 2007, at 10:42 PM, Jacek wrote:
>
>
>
>> Hi Katharine
>>
>> The lamp black is Windsor and Newton, any suggestion for another
>> type of black tube paint from them you would recommend in getting
>> a nice jet black colour? Ivory black or Neutral tint by W&N perhaps?
>>
>>
>
> Ivory black is an easier color to work with, but tends toward brown
> rather than grey in all tones but the darkest (see
>
>
http://www.pacifier.com/~kthayer/html/kids.html
>
> for an example of a gum print in ivory black) so if you want
> neutral greys, it may not be the best choice. But if you want a
> rich brown, it's a very good choice. So depends what you're after.
>
>
>
>
>> Another question I have is with the Potassium Dichromate, is it
>> worth reducing the saturation of this to get a longer tonal scale?
>> What would I be missing out if I reduced it?
>>
>>
>
> In my experience, reducing the dichromate concentration will
> reduce, rather than lengthen, the tonal scale (you get fewer steps,
> rather than more). See
>
> http://www.pacifier.com/~kthayer/html/Dichromate.html
>
> for a discussion of the relationship between dichromate
> concentration, speed, and contrast, with examples. So if you want
> a longer tonal scale than you can get with saturated potassium
> dichromate, you should consider going to ammonium dichromate.
>
>
>
>> I guess time for exposure would be more, that is if I used exactly
>> the same amount of gum and pigment, as I did for the same
>> saturated solution of Potassium Dichromate.
>>
>>
>
> Yes, diluting the dichromate increases the exposure time.
>
>
>
>> My understanding would be to change the negative using the
>> photoshop curve to get the full graduation of tonal scale and
>> leave the Potassium Dichromate saturated as it is.
>> The only 2 variables I should worry about are the Gum and Pigment.
>> Is this assumption correct or partly correct or just try it and
>> see where it takes me :)
>>
>>
>
> Well, the main thing is to try not to change more than one
> variable at a time, so that you can see the effect of each
> variable. Good luck,
> Katharine
>
>
> On Apr 23, 2007, at 10:42 PM, Jacek wrote:
>
>
>> Hi Katharine
>>
>> Thanks for the info. I'll test the Arches paper tonight with the
>> boiled up shrinking and let you know how I go.
>> I haven't used any hardeners as yet because I can't seem to find
>> any here in Perth, still looking..
>>
>> The lamp black is Windsor and Newton, any suggestion for another
>> type of black tube paint from them you would recommend in getting
>> a nice jet black colour? Ivory black or Neutral tint by W&N perhaps?
>> The gum solution was 33%. I used 5ml of that with 2 small dots of
>> Windsor and Newton lamp black. With 5ml Potassium Dichromate
>> Saturated Solution.
>> I'll try my hand at reducing the lamp black and see what I get.
>>
>> I'll try the foam padding under the paper to get the maximum
>> contact of the negative and glass.
>>
>> Another question I have is with the Potassium Dichromate, is it
>> worth reducing the saturation of this to get a longer tonal scale?
>> What would I be missing out if I reduced it?
>> I guess time for exposure would be more, that is if I used exactly
>> the same amount of gum and pigment, as I did for the same
>> saturated solution of Potassium Dichromate.
>> My understanding would be to change the negative using the
>> photoshop curve to get the full graduation of tonal scale and
>> leave the Potassium Dichromate saturated as it is.
>> The only 2 variables I should worry about are the Gum and Pigment.
>> Is this assumption correct or partly correct or just try it and
>> see where it takes me :)
>>
>> Thanks
>> Jacek
>>
>> On Tue Apr 24 1:55 , Katharine Thayer <kthayer@pacifier.com> sent:
>>
>>
>>
>>> Hi Jacek,
>>>
>>> Perhaps I wasn't clear in communicating my experience with Arches
>>> paper before. There are two issues: (1) in my experience, Arches
>>> paper as now formulated can't be printed unsized because of
>>> speckles. If you got a good result by shrinking it with boiling
>>> water and printing unsized, that's interesting, and inconsistent
>>> with
>>> what I've seen before. The rule with gum is, use whatever works; if
>>> boiling water works for you, go for it. My experience has been that
>>> treating with very hot water just messes with the internal gelatin
>>> size, but that's the thing about gum, we often get contradicting
>>> observations. (2) When sized, my experience is that the sizing for
>>> Arches should be kept below 140 or I get speckles in the sized
>>> paper,
>>> but as people are always saying, your mileage may vary. I harden
>>> with glyoxal.
>>>
>>> About your problem with incomplete contact, it may not be that the
>>> glass isn't heavy enough; your problem may be on the back side of
>>> the
>>> paper. When I first started printing gum, I had the same problem; I
>>> had a piece of smooth wood on one side of the paper and a piece of
>>> plate glass holding the paper to the wood, but I had areas in the
>>> print where it was obvious there was inconsistent contact. I got
>>> some interfacing from the fabric store, sort of a webby stuff, but
>>> foam rubber or something similar would probably work as well, to
>>> place between the wood and the back of the paper, and that's all
>>> I've
>>> used ever since to get good contact. It holds the paper securely
>>> against the glass.
>>>
>>> Two pea-sized pieces of lamp black in how much gum? What brand of
>>> lamp black? I might be inclined to guess just on general principles
>>> that you may be using too much pigment, only because in my
>>> experience beginners almost always use too much lamp black to start.
>>> Lamp black is a very powerful pigment; a little goes a long ways.
>>> Try cutting your lamp black by half by adding more gum; if you still
>>> get a dark black where you want a dark black but no staining, then
>>> the staining was probably due to too much pigment rather than
>>> insufficient sizing. I've got an example on my website that shows
>>> the difference between way too much lamp black and half that
>>> much, if
>>> you want to compare what you're observing:
>>>
>>>
http://www.pacifier.com/~kthayer/html/stain.html
>>>
>>> I coat paper in daylight or under a 60-watt tungsten light with no
>>> problem; a safelight isn't necessary. Just don't do it in direct
>>> sun.
>>>
>>> Katharine
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Apr 23, 2007, at 9:17 AM, Jacek Gonsalves wrote:
>>>
>>>
>>>
>>>> Hi all,
>>>>
>>>> Well I finally took the plunge on the weekend and did my first ever
>>>> print in gum.
>>>> The results were...well something actually came up and I can see I
>>>> have
>>>> a long way to go! :)
>>>>
>>>> I used W&N lamp black tube, found I couldn't weigh it on my scale
>>>> when I
>>>> squeezed 2 pea sizes out, nothing registered on the scale! :)
>>>>
>>>> The paper itself got stained perhaps of too much pigment or
>>>> because I
>>>> didn't add enough gelatin to the paper?
>>>>
>>>> My paper seemed to have curled and the negative seems to not
>>>> have sat
>>>> comfortably on it, even with a heavy glass on. I might have to put
>>>> something heavier or try keeping the paper flat when drying with
>>>> all the
>>>> preshrinking and gelatin. Perhaps I can find plans on the net to
>>>> build a
>>>> Contact Frame?
>>>>
>>>> The Arches paper Smooth 300gsm, I had an issue with dotted
>>>> speckles, I
>>>> found that the water preshrinking I used wasnt that hot. The water
>>>> couldnt penetrate the whole paper, therefore getting speckles in
>>>> the
>>>> paper. Also the fact I was preshrinking for only 10 mins.
>>>> I used this paper to develop a print, and the part where you can
>>>> see the
>>>> dotted speckles, has been stained with the lamp black pigment, the
>>>> rest
>>>> seemed unstained.
>>>>
>>>> I ended up using boiling water to preshrinking another batch of the
>>>> same
>>>> Arches paper, and I got no more speckles! Though I might have
>>>> damaged
>>>> the actual manufacturers hardening of the paper? Also it really
>>>> gave off
>>>> fumes with the boiling hot water, I had to take it outside.
>>>>
>>>> I tried a batch, Katharine suggestion of below 140F(60C),
>>>> unfortunately
>>>> it still has the dotty speckles. I changed the water at least 4
>>>> times,
>>>> their still there! :(
>>>>
>>>> Reading the Altlist I see some people just use lukewarm water to
>>>> preshrinking?
>>>> Also what paper do you use and how do you preshrinking it? With
>>>> boiling
>>>> hot water, lukewarm water etc?
>>>>
>>>> I also tried Acquarello Fabriano cold press with no preshrinking, a
>>>> brushed on gelatin on one side. Developed the paper and got
>>>> staining.
>>>> Perhaps another gelatin coat would have fixed it or less pigment?
>>>> I'm not using any hardners in my gelatin and perhaps that could
>>>> also
>>>> account for the staining.
>>>>
>>>> Is a RED safelight, ones used in the darkroom safe to use when
>>>> coating
>>>> gum? What do you use?
>>>> More to come...
>>>> Thanks
>>>> Jacek
>>>>
>>>>
>>>>
>>>>
>>
>>
>>
>
>
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