by Ed Wesly » Tue Jul 14, 2015 1:22 pm
Temperature plays an important role in photographic development. Instructions for black and white photographic film would include a chart that prescribes the development for a range of temperatures, typically from 20C to 24C (68F to 75F), or room temperature. Developers are relatively inactive below that range, and bad things can happen at higher temperatures, like emulsions lifting off, but also the reaction gets out of hand. Manufacturers of B & W printing papers usually give a suggested development time at 20C.
Holographic plates are more like photographic printing papers than film. Agfa never gave time versus temperature tables for Holotest films and plates, just 2 minutes @ 20C.
http://edweslystudio.com/Formulae/Devel ... ochure.PDF I have often heard that Lon Moore would develop his masters of flowers on Agfa plates at 90F (32C) to cut down exposure times, but there could be the risk of fog, meaning development of unexposed grains, which translates into noise, the bluish-white haze in the image that never gives a good black.
The key to success is keeping the process consistent. If you decide on 20C, or any other ambient room temperature which is easy to maintain, do so. You may want to make some exposure tests and develop them for different lengths of time, but you will find that the longer times, although needing less exposure for decent brightness, bring up the noise.
I have found that the Sphere-S GEO-3 performs better at 65F (18C) maybe because the gelatin is softer, and I learned that trick from TJ (may he rest in peace) from his work with PFG-03M, but not -03C, but all these are in a similar category.
http://edweslystudio.com/HnEPortfolio/ColdJD4.html Geola recommends a formaldehyde based pre-hardener for these materials before development at room temperature, but that extra step may not be to your liking.
Find what is comfortable for you to use, both time and temperature wise, and stick to it, because you will hear a variety of opinions here. There is an optimum density for all holographic materials, and how you get there is a combination of exposure time, and development time combined with temperature.
Temperature plays an important role in photographic development. Instructions for black and white photographic film would include a chart that prescribes the development for a range of temperatures, typically from 20C to 24C (68F to 75F), or room temperature. Developers are relatively inactive below that range, and bad things can happen at higher temperatures, like emulsions lifting off, but also the reaction gets out of hand. Manufacturers of B & W printing papers usually give a suggested development time at 20C.
Holographic plates are more like photographic printing papers than film. Agfa never gave time versus temperature tables for Holotest films and plates, just 2 minutes @ 20C. [url]http://edweslystudio.com/Formulae/Developers/AgfaBrochure.PDF[/url] I have often heard that Lon Moore would develop his masters of flowers on Agfa plates at 90F (32C) to cut down exposure times, but there could be the risk of fog, meaning development of unexposed grains, which translates into noise, the bluish-white haze in the image that never gives a good black.
The key to success is keeping the process consistent. If you decide on 20C, or any other ambient room temperature which is easy to maintain, do so. You may want to make some exposure tests and develop them for different lengths of time, but you will find that the longer times, although needing less exposure for decent brightness, bring up the noise.
I have found that the Sphere-S GEO-3 performs better at 65F (18C) maybe because the gelatin is softer, and I learned that trick from TJ (may he rest in peace) from his work with PFG-03M, but not -03C, but all these are in a similar category.[url]http://edweslystudio.com/HnEPortfolio/ColdJD4.html[/url] Geola recommends a formaldehyde based pre-hardener for these materials before development at room temperature, but that extra step may not be to your liking.
Find what is comfortable for you to use, both time and temperature wise, and stick to it, because you will hear a variety of opinions here. There is an optimum density for all holographic materials, and how you get there is a combination of exposure time, and development time combined with temperature.