Re: pyro developed negs for cyanotype?

Diana,

The long and the short of it is that negatives that are well-exposed
and developed in a pyro staining developer should not print any
slower than negatives that are well-exposed and developed in
non-staining developers.

I strongly suspect that the problem with the Fujifilm is a UV coating
of the type that TMAX-100 has. This coating, as others have
mentioned, amounts to UV filtration of about log 1.00, or more than
three full stops of exposure.

I have never used Fujifilm but know of no reason other than UV
filtration that could explain such long printing times for negatives
that look good to the eye. However, I would be happy to test the film
by taking a densitometer reading in UV mode if you could manage to
get the gentleman in question send me one of his scratch negatives.

Sandy

>Thanks, Loris. We used the classic cyanotype formula. The white
>vinegar bath did occur to me, along with diluting the sensitizer
>itself at one point. The lights themselves get warm, but the
>lightboxes had good fans that also kept the lights relatively cool
>(not hot), and the other students were using the same lightboxes and
>having no problems with longer than normal exposures. He also tried
>the sun. So I'm thinking it's a combination of the Pyro and,
>perhaps, Fuji b&w has this same UV blocking layer, like TMAX?
>On Oct 31, 2004, at 6:25 PM, Loris Medici wrote:
>
>>Hi Diana,
>>
>>Don't know if you have already tried what I'm suggesting below but
>>will write anyway (please forgive if you already know and/or tried
>>these workarounds...)
>>
>>What formula were you using (classic or new cyanotype)? Have you
>>tried acid development (white vinegar, 5% glacial acetic acid, 5% -
>>or stronger - citric acid)? If the negatives are too contrasty for
>>straight cyanotype formula (old or new doesn't matter) developing
>>in acidic water may decrease the contrast of the paper (even you
>>can try to add some acid to the coating solution... others: does
>>this sound like a good solution?)
>>
>>If the problem isn't solely based on some sort of UV-blocking film
>>base, acid development may certainly help - along with prolonged
>>exposure times of course. But if the contrast is too high, even
>>this modification may not help. Another point that comes to my
>>mind: maybe you have to try intermittent exposures if you're using
>>flourescent tubes. If they get too hot, their UV output is greatly
>>reduced - which means that increasing the exposure times by 2 stops
>>may not translate to a "real/practical" 2 stops increase...
>>
>>Regards,
>>Loris.
>>
>>----- Original Message ----- From: "Diana Bloomfield"
>><dhbloomfield@bellsouth.net>
>>To: <alt-photo-process-l@sask.usask.ca>
>>Sent: Monday, November 01, 2004 12:27 AM
>>Subject: Re: pyro developed negs for cyanotype?
>>
>>>Thanks, Joe. This was Fujifilm, but I've never used b&w 4x5
>>>Fujifilm, so I don't know how new it is, or whether it is
>>>suffering the same fate with the film base as TMAX 100, but it
>>>sounds like it. A 4 hour exposure would have been about right, I
>>>think!
>>>...
Received on Sun Oct 31 18:08:40 2004