Re: Cyanotype blotches

From: Michael Koch-Schulte ^lt;[email protected]>
Date: 02/17/05-08:24:57 PM Z
Message-id: <000801c51561$0aa195e0$6e00a8c0@Sweetwood>

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:
> * 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 []
>> Sent: Thursday, February 17, 2005 7:22 AM
>> To:
>> 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 Thu Feb 17 20:25:32 2005

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