Re: Cyanotype blotches

Michael,

I gather that you're beginning cyano with the Ware formula...which is
about 50,000 times trickier than plain old cyano... and unless you have
some specific need or goal, might not be the best entry.

My experience is only with regular or "classic" cyano, but tho that takes
well to most paper, it doesn't really like Rives BFK. BFK cyano doesn't
give the fine detail cyano is capable of, and tends to white flecks
(probably from paper fibers). Another point worth mentioning is that heat
drying the emulsion is a big variable in exposure -- both speed and range.
Your note that you only saw 5 steps also seems odd... Classic cyano
usually does 8 steps -- and, if memory serves, the Ware cyano has an even
longer scale.

As for the blotches, I didn't understand the explanation you came up with,
but I thought also it could be contamination (to cyanotype) on the belt.
It's been accepted that the Ware formula is goosier contamination-wise
than the old, which may compound such problems.

Judy

On Thu, 17 Feb 2005, Michael Koch-Schulte wrote:

> 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 Thu Feb 17 20:49:12 2005