U of S | Mailing List Archive | alt-photo-process-l | Re: Measuring humidity

Re: Measuring humidity


Temperature certainly is a variable, but my home is 70 degrees year round and it's the humidity that can vary a lot.  Humidity has a LOT of influence—at least with PT/PD.  But then, as you say, I am holding my temperature constant—and wearing the same lucky undershorts.

Best Wishes,
Mark Nelson

Precision Digital Negatives - The System
PDNPrint Forum at Yahoo Groups

In a message dated 9/28/06 7:58:11 PM, kthayer@pacifier.com writes:

But apparently I'm not the only one making this mistake, because 
we've all been using RH as if it were a meaningful variable, and 
obviously it's not, unless, as you say, temperature is held 
constant.  The graphs in the literature showing the relationship 
between humidity and dark reaction, and humidity and sensitivity, 
were no doubt constructed holding temperature constant.  
Unfortunately they don't say that, or specify the temperature, 
although I suppose we could assume 25C, isn't that the usual standard