U of S | Mailing List Archive | alt-photo-process-l | Re: Unknown area in Gum printing?

Re: Unknown area in Gum printing?

Hi all,

If you want me to upload more detailed images of each let me know.
The negative is made by an imagesetter, I used a 2% increment grey scale file made in photoshop.

This is the Arches w/c 300gsm smooth paper. 
Print looks very light.

The first one, 4min, its a bit messy with me adding a clip on left, in the middle of the paper when I had to dry it, it took some w/c out :|
The numbers can be distinguished.
16to20% above it, not so sure what I did there possibly sprayed the potassium Metabisulfite a bit too close?
0 to 30% seem fine to me, though after that things start looking messy, there seems to be a vertical light smudging, plus yellowing from 86% to 100%, possibly needs more potassium metabisulfite.

The next, 6 mins. 
The print start looking smudgy at 52% onwards. Perhaps too much yellowing from the dichromate stain? 
The bottom 92% onwards was at the edge of the paper and there probably wasnt enough coating there, thats why it looks uncoated and speckly.

The next 8 mins. 
The clips there again in the middle :|
You can clearly see that with more time, the 10% is darker than the 4mins one.
Same sort of vertical yellow streaking/smudging in the shadows.

Next image:
Fabriano Acquarello 300gsm

First one, 8min.
The clip smudged the paper in the middle?
From 0 to 40% it looks ok.
Then It starts getting discoloured after that, with yellowing on the print. The scan your looking at doesnt seem to represent in colour to what the print does.

The next, 12min
This seems to look ok from 0 to 32%. From there it looks dark and smudgy.


The colour doesnt seem to be constant in the shadows. It has streaks of lighter tones?
I think I could be overexposing too much? 
Possibly need to add more gum?

Relative humidity is 60%-65%, Black Light Blue tubes 18 watts.

Thanks everyone for the help, I appreciate it! :)

 On Thu Apr 26 21:11 , Katharine Thayer <kthayer@pacifier.com> sent:

>Hi Jacek,
>One initial observation is that pigment stain will affect the  
>highlights and unexposed areas of the paper as well as the shadows,  
>so if your highlights and the unexposed parts of coated areas are  
>clear, then pigment stain probably isn't an issue.  And from the  
>description ("a small smudge") of the amount of lamp black you used,  
>it seems unlikely that overpigmentation is an issue either.  The  
>pictures will help a lot, so I'll reserve further comment til you can  
>upload them, thanks,
>What are you using as a light source?  What's your ambient humidity  
>On Apr 25, 2007, at 11:24 PM, Jacek wrote:
>> Hi all,
>> I tried my second attempt. Just a basic outline first on what I did.
>> Arches smooth 300gsm and Fabriano Acquarello 300gsm
>> 1. boiling water pre shrinked for 10mins. Dried for a day.( no more  
>> speckles in the Arches)
>> 2.Gelatin 3g to 500ml, cold water for 10 mins... Heated to 43  
>> degree Celsius.
>> 3.Added paper to the tray of gelatin for a minute, took excess  
>> gelatin off by sliding the paper on the side of the tray. Dried for  
>> the day. Stored the same Gelatin in the fridge
>> 4.Reheated the gelatin the next day. Recoated the paper the same  
>> way. Dried.
>> Didnt add any hardner as yet, as I cant seem to get time to go buy  
>> any! :)
>> 5ml 13% Pot Dich + 5ml Gum 35% + Windsor&Newton LAMP BLACK a very  
>> SMALL smudge! (coudnt get any Ivory black as yet, will do so..)
>> Coated paper, fan dried for 15mins.
>> Added a negative with squares 2% increments made in photoshop from  
>> white to black. Each 2% square has a number on it, which should  
>> clearly be seen when printed.
>> The sheet of Arches had 3 of the same negatives on it, each exposed  
>> 4, 6, and 8 mins. Just covered each negative when it passed the min  
>> mark.
>> Developed for 5 mins face down in room temp water.
>> Next tray developed for 5 mins face down in room temp water.
>> Next tray developed for 20mins same room temp water.
>> On the Arches paper I got:
>> What I got was NO staining in highlights or midtones or the whole  
>> paper. They looked ok though a little on the light side the tones  
>> came up.
>> Can read all the incremented 2% numbers in those areas.
>> The shadows are another business altogether, what I got was a  
>> massive yellow staining probably from the dichromate, plus it  
>> looked like a real mess as I couldnt really make out the  
>> incremental numbers from the negative. The mess seemed like too  
>> much watercolour overpigmented, its not one colour but just smudges  
>> of watercolour and yellow staining.
>> Reading Katharine suggestions, I'm thinking what I'm looking at  
>> could be OVERexposure? or the small Smudge I used from the lamp  
>> black is still too much pigment!?
>> I doubt it was caused by overcoating, as I turned each of the 3  
>> negs upside down side by side, got the same result on each part of  
>> the print.
>> Could it be my sizing, and not using a hardner? Though the  
>> Highlights and Midtones look good?
>> I got kind of fed up looking at the yellow staining and used a 5%  
>> potassium metabisulfite solution, sprayed with a hand held spray  
>> gun. Didnt work as well, next time i'll use a tray bath.
>> The other Fabriano Aquarello paper I'll add more info on it later  
>> can't recall what it looked like, but had the same sort of problems  
>> as above.
>> I'll scan the prints when I get home and upload to a website.
>> Cheers
>> Jacek