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,
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 73Â°
> 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"
> 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
>> 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.
>> 30 Mart 2009, Pazartesi, 11:48 pm tarihinde, Ken Sinclair yazmÄ±Å�:
>>> 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?
>>> Quando omni flunkus moritati (R. Green)
> Quando omni flunkus moritati (R. Green)