Re: Unknown areas in Gum printing?, etc.
In NYC formaldyhde is available in 1 liter size from pharmacy, but requires prescription... do you have a friendly doctor or mortician? As for gum + dichromate as hardener, I've tried it carefully, as have others. IMO its a PITA... very difficult or impossible to remove all subsequent tone, and has a different effect as base for print. In the matter of exposure -- with a digital neg, mine are 1 minute. And in the US, you can buy glyoxal from Artcraft. Judy. On Fri, 27 Apr 2007, kerik@kerik.com wrote: Yes, you probably don't want 5L of formaldehyde. I was able to get a 1-pint bottle from a local pharmacy. Perhaps you could try that? Kerik kerik.com Original Message: ----------------- From: Jacek gonsaj@iinet.net.au Date: Fri, 27 Apr 2007 15:59:39 +0800 To: alt-photo-process-l@usask.ca Subject: Re: Unknown area in Gum printing? Hi, Thanks for that. I have to readjust how I brush the coating. Change the pigment concentration and get some hardening. The hardener, I just spent a whole lot of time sourcing it and came up with only one company only selling 5 litres of formaldehyde and nothing less, one of the reasons I'm reluctant to get it. I cant even get it from overstate or overseas with all the security regulations :| Though I havent looked for others like Chrome alum or glyoxal, I think its best if I do. Cheers guys. Jacek On Fri Apr 27 3:04 , Katharine Thayer <kthayer@pacifier.com> sent:Jacek, this is way underpigmented for lamp black, so as I guessed earlier, pigment stain due to overpigmentation is definitely not your problem here, as you might have seen if you'd checked the comparison images I pointed to for lamp black. I'd agree with Judy; your stain in highlight areas (and I'd definitely call that pigment stain in the highlights on the Arches) is probably a function of the unhardened size. It's interesting that the unhardened gelatin seems to work better on the Fabriano paper. I agree that tray clearing is probably better than spraying the clearing agent on. kt On Apr 26, 2007, at 10:32 AM, Jacek wrote: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. http://www.jagnight.com/Archesall3.jpg 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: http://www.jagnight.com/Fabriano812.jpg 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! :) Jacek On Thu Apr 26 21:11 , Katharine Thayer kthayer@pacifier.com> sent:
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