Re: speaking of gum dichromate
Kees, do you use the agar-agar layer on top of the tissue or you do it w/o it? BTW, wire coated rods gave me horrible streaks with pigmented gelatin. I hope this proves false for you. Regards, Loris. 16 Haziran 2008, Pazartesi, 1:16 pm tarihinde, Kees Brandenburg yazmış: > Hi all > > Some more info on Halvor Bjørngård's Chiba system is here: > http://photorelief.googlepages.com/thechibasystem > > Halvor describes the colloid hardening properties of > FerricAmmoniumCitrate (!) for carbon transfer and direct carbon. Its a > must read for all dichromate users! > > I have been testing the gelatin variant of his direct carbon method. > It's a very interesting and working approach! A warm pigmented gelatin > is sensitized with Ferricammoniumcitrate and coated very thin, like > gum, on paper. After exposure the paper is put in a very dilute > peroxide bath for 5 seconds to get the hardening reaction. After that > the non-hardened gelatin is removed in a 'cabon' way in warm water (38 > degrees). Like gum printing several layers adds density. > > pro's: > -no dichromates, safer and cleaner printing! > -no dark effect, no hardened size needed > > con's; > -warm pigmented gelatin is very difficult to coat thinly whithout > streaks > -a nonhardened sizing is needed before each layer but gum can also be > used in stead of gelating > -it is not working with gum, it would wash off in the peroxide befor > hardening. A workaraud is also in the thesis but at the cost of a dark > effect. > > I will continue to experiment. Next step will be coating with a > threaded rod instead of a brush. > > kees > > http://polychrome.nl
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