Re: Humidity and Sensitivity... Platinum  and so on...

Eric,

Very well said.

I became fully aware of the effect of temperature and humidity with PT/PD
when I was putting together the Precision Digital Negative system. It was
really driven home late last fall when the furnace kicked in and printing suddenly
went to pieces. I bought a nice little digital thermometer/hygrometer from Ace
Hardware for about $20. That coupled with a nice little Holms Humidifier
has resulted in no problem since then. I found that maintaining a level of
relative humidity in the 50-60% range was important to good printing with PT/PD and
had this confirmed by a number of expert printers.

I finally standardized on a specific humidity level and a method of
pre-humidifying my paper before coating and a specific drying time and method. The
system I am using for printing with digital negatives will indicate very slight
variances.

It is much easier to control a situation where you have low humidity than
high humidity, since it is easier to add than subtract. Places where there is
very very high humidity on a regular basis must present a real problem.

I think people around the country have very different humidity issues or
non-issues, depending on the consistency of the relative humidity and variance
with seasons. Most people have probable just built it into their workflow—
sometimes without being aware that they were doing so, but getting good results
just the same. I think it is probably one of the most important and most ignored
issues in printing.

Mark Nelson
www.precisiondigitalnegatives.com

In a message dated 8/5/04 9:45:30 AM, e.neilsen@worldnet.att.net writes:

> Ray, Heat and Humidity are ALWAYS important throughout the process.  That
> being said, it is not always critical nor does it remain the same issue at
> each phase of the print production process.  The paper will get treated by
> the practitioner before the coating of the sensitizer, gum, sizing, et la.
> The coated paper is then handled carefully to the next step, and so on until
> the finished print lay on the table with the eyes of its creator lovingly
> looking down upon it.  With the platinum/palladium family of print making,
> humidity affects the way the coating solution is absorbed and thus how much
> or how little solution to use.  In the drying of the paper, it
> allows/prevents the penetration of the solution.  In the exposure it plays a
> roll in speed, color and contrast. 
>
> AS you print, you begin to see how critical control of humidity and heat
> become.  This understanding and others like it can allow you to control the
> process rather than it controlling you.
>
> Have fun!
>
>
> Eric Neilsen Photography
> 4101 Commerce Street
> Suite 9
> Dallas, TX 75226
> http://e.neilsen.home.att.net
> http://ericneilsenphotography.com
>
Received on Thu Aug 5 11:28:55 2004