Does anyone have any experience with clearprint 16# drafting vellum in rolls, and a better presoak than 4% oxalic acid? I do not want to size the vellum with starch or gelatin -- I want the vellum's hard, bright surface along with the potential to transparentize the paper should I later so choose.
My Texas Chrysotype process (ammonium ferric-ferrous oxalate+10% Au) prints out beautifully on precut sheets of Clearprint 16# drafting vellum; however, chopping my own sheets off a 20 yard roll, for a print larger than the 6.5x8.5 contacts I usually make, I have encountered two problems (one of which I already solved):
I suspected my AFFO left over from paper tests I conducted in January had decayed too far. I tested that theory by mixing up a quick Ziatype+ -- palladium and ammonium ferric-ferrous oxalate (prepared with 8 drops of 2% ascorbate to 10 ml 40% amm ferric oxalate). That printed out better than gold, but would need a contrast boost. My test was flawed however because too little ferrous iron in the AFFO also yields poor contrast in dry print out with palladium and platinum.
Cheers
My Texas Chrysotype process (ammonium ferric-ferrous oxalate+10% Au) prints out beautifully on precut sheets of Clearprint 16# drafting vellum; however, chopping my own sheets off a 20 yard roll, for a print larger than the 6.5x8.5 contacts I usually make, I have encountered two problems (one of which I already solved):
- Gold prints out red (like a Chrysotype S) instead of gray scale like a Texas Chrysotype (for which paper should be bone dry, not humidified). (Solution: presoak the paper in 4% oxalic acid. This gave rise to a new problem: in any first acid bath no matter how weak the print quickly darkened almost to black. Water turned it a ghastly blue-purple. Solution: switch to an alkaline bath, in this case ~.06% bleach.)
- Contrast is quite low with weak Dmax. Working on solution for this over the weekend.
I suspected my AFFO left over from paper tests I conducted in January had decayed too far. I tested that theory by mixing up a quick Ziatype+ -- palladium and ammonium ferric-ferrous oxalate (prepared with 8 drops of 2% ascorbate to 10 ml 40% amm ferric oxalate). That printed out better than gold, but would need a contrast boost. My test was flawed however because too little ferrous iron in the AFFO also yields poor contrast in dry print out with palladium and platinum.
Cheers
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