Re: BL light box 'blues'
Let me see, 2:2:100 73C 13mins... it's Tmax-400 right? Well, I can't say anything other than suggesting to expose a test sheet (w/o any negative) in the contact printing frame, covering (or uncovering) it gradually too find out the minimum 'black' exposure for your emulsion / lightsource combination and see how that compares to others' timings. With my lightsource (bulbs 2" above frame glass) I would get something like 5:45 (no negative, 6:30 with Pictorico negatives) to achieve a convincing black with 2A:1B trad. cyanotype. Hope this helps, Loris. 31 Mart 2009, Salı, 12:46 am tarihinde, Ken Sinclair yazmış: > Hi Loris... > > I checked out Sandy King's article on introductio to Pyrocat-HD where > I observed > his recommended 2:2:100 (distilled) water to achieve a log density > of .080 - .085 for > VDB.. so the negatives received a developing time of 13 minutes at 73° > F... > They look OK to my eye.... although the 'stain' is not as obvious to > the eye as the stain > I am used to with PMK. > > The negatives do not seem to be what one might consider "bulletproof" > > Ken > > > > > On 30-Mar-09, at 3:04 PM, Loris Medici wrote: > >> >> Maybe your Pyrocat negatives are way too dense? They can get perfectly >> bulletproof negatives (in case of overdevelopment) while they fake >> like >> being thin; the brownish stain is a pretty strong UV light blocker! >> >> What film, EI, Pyrocat dilution (A?B?H2O?) and development time (and >> regime) have you used for the negatives? Maybe someone with good >> experience with Pyrocat may evaluate this info and tell you if you're >> indeed overdeveloping the negatives. >> >> Regards, >> Loris. >> >> >> 30 Mart 2009, Pazartesi, 11:48 pm tarihinde, Ken Sinclair yazmıÅ�: >>> Have recently decided to intensify my interest in non-silver, I >>> constructed my >>> new UV light-box using 10 BL tubes presently 5 inches above my >>> printing frame. >>> >>> So that I could use the same negatives for both silver-gelatin, >>> Cyanos and VDB >>> I switched to Pyrocat as a developer... and I must admit, they do >>> look "sweet". >>> >>> A few years ago my southern Alberta summer sunlight exposures for >>> Cyanos were >>> running around the eight minute mark... which expanded to around two >>> and a half >>> hours in the rather weak December sun. >>> >>> The exposure times I expected using the new 24" BL tubes are nowhere >>> as short as I had >>> hoped... Cyanotypes seem to be requiring around 40 to 50 minutes >>> while I have not >>> yet reached the 'end-point' for acceptable VDB exposures, it seems as >>> if 60 -70 minutes >>> might be the absolute minimum. >>> >>> I do not have a stouffer wedge to assist reaching my standard >>> exposure times, my patience is >>> wearing (as my frustration level rises). >>> >>> I have just put a VDB out on the deck to enjoy some natural UV rays >>> from the sun >>> for a time comparison... >>> >>> Are my BL light-box test exposure times "out of line" with times >>> experienced by others? >>> >>> Ken >>> >>> Quando omni flunkus moritati (R. Green) >>> >>> >> >> > > Quando omni flunkus moritati (R. Green) > >
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