[alt-photo] Re: cyanotype

[Loris Medici]

As for the "why?" I would suggest that you try to add a drop of 40%
citric acid into 10ml sensitizer and see if it gets better. If yes,
then it's probably chemical fogging (always more noticeable in the
highlights) due combination of increased sensitivity and paper
impurity (or sensitizer contamination?)...

Regards,
Loris.

P.S. Sorry for the "stuttering" postings...


2010/6/2 Loris Medici <mail at loris.medici.name>:
> BTW, remember FAC is incredibly hygroscopic and deliquescent,
> therefore it's pretty normal that the paper doesn't want to get dry in
> very humid environment.
>
> Regards,
> Loris.
>
>
> 2010/6/2 Loris Medici <mail at loris.medici.name>:
>> Christina that's my standard practice with cyanotype. I always expose
>> hot air force dried paper (after paper absorbed the sensitizer
>> completely that is - usually takes not more than 4-5 minutes...) for
>> sake of consistency. That way my exposure times and contrast remain
>> constant in all seasons / environmental conditions...
>>
>> Humidity increases sensitivity a lot and maybe that is causing the
>> chemical fogging (my interpretation) which doesn't kick in when you're
>> under a specific sensitivity threshold (with thoroughly force dried
>> paper)... ???
>>
>> Regards,
>> Loris.
>>
>>
>> 2010/6/2 Christina Anderson <zphoto at montana.net>:
>>> ...
>>> We've taken to blow drying the paper with blow dryers til "snappy" to alleviate it.
>>> ...
>>
>