RE: Cyanotype blotches

Hi Michael, I'm glad that you managed to locate the source of the
problem.

* I coat the papers in an air conditioned room.
* I wait around 2 - 3 minutes (or until the paper doesn't look shiny
when looking from an oblique angle) to let the paper soak up the
emulsion.
* Then, I use a cold air fan in order to circulate fresh/unmoistened air
around the papers. For 25 - 30 minutes.
* Then I start to print.

I printed classic cyanotype coated papers as old as 1 week (stored in a
simple light-tight cardboard box) with no adverse effects (well, frankly
I experienced very slight contrast decrease and highlight yellowing with
these "old" papers but it was very subtle and definitely not disturbing
to my eyes). I'm sure if I had stored the coated papers in an
"air-tight" + light-tight box which include some sort of desiccant I
would manage to store the papers much longer (maybe a month?) without
ill effects. I never tried to age cyanotype 2 coated papers so I cannot
comment on how much they last before going bad.

Hope this helps,
Loris.

> -----Original Message-----
> From: Michael Koch-Schulte [mailto:mkochsch@shaw.ca]
> Sent: Friday, February 18, 2005 4:25 AM
> To: alt-photo-process-l@sask.usask.ca
> Subject: Re: Cyanotype blotches
>
>
> How long do you leave the sensitizer on the paper before
> exposure? Does this have any affect? I think you were right.
> On my next tests I carefully remove all tap water from my
> syringes and the problem did not reappear. If I didn't clean
> the syringe could that also cause contamination? It would
> appears that the Rives paper is a poor choice for cyanotype
> or possibly I need to treat it differently.
>
> Loris Medici wrote:
> > FWIW,
> >
> > * You may try to increase the amnt. of clearing agent: I
> use 2 drops
> > of 40% citric acid per ml of Cyanotype II sensitizer in the coating
> > soln. * Have you tried to use another paper? That way you
> can check if
> > the problem is due to the paper you're using.
> > * Do you use tap water to rinse the coating apparatus?
> Maybe there's
> > iron in your tap water, use drinking water without iron to
> rinse your
> > brush/coating rod ect.
> >
> > Regards,
> > Loris.
> >
> >> -----Original Message-----
> >> From: Michael Koch-Schulte [mailto:mkochsch@shaw.ca]
> >> Sent: Thursday, February 17, 2005 7:22 AM
> >> To: alt-photo-process-l@sask.usask.ca
> >> Subject: Cyanotype blotches
> >>
> >>
> >> ...
> >> First, I noticed 5-10mm blotches all
> >> over the papers like salt sprinkles. The Beinfang's blue
> was OK (not
> >> as nice as the initial test) but the sensitiser
> practically fell off
> >> the Rives BFK paper during the wash rinse -- today using a kodak
> >> siphon tray running slooowly. I use a 10ml syringe fitted with an
> >> extension tube to draw my cyano solution from it's bottle and a
> >> separate dedicated eye dropper for adding the clearing
> agent. I drew
> >> 2ml of sensitiser and used one drop of clearing agent.
> It's possible
> >> that there were water droplets in the syringe from being
> >> cleaned after the first use, or possibly water in the sponge
> >> coating brush which I also cleaned with water yesterday. What
> >> other sources of contamination are common in this process?
> >> Could heat from the print dryer cause problems? 125F doesn't
> >> seem very hot. BTW the blotches were first evident after the
> >> initial coating of sensitiser had dried and I examined the
> >> paper coming out of the dryer, I thought maybe they would go
> >> away but development made the problem quite obvious. Also on
> >> the second test I "worked" the brush a little longer and
> >> harder into the paper probably making at least 4 or 5 passes
> >> to ensure the sensitiser was "in" the paper.
> >> ...
Received on Mon Feb 21 12:08:08 2005