Some pre-emulsion making questions . .
I'm about to give a go at making a basic emulsin to coat on glass for my 13x18 plate camera. I've assembled all the bits and pieces (including a magentic hot plate stirrer) and have a coupe of questions.
1. If my darkroom safe light (red) is safe enough to not fog paper for several minutes, is that dark enough for emulsion mixing purposes? How do I know if the light is OK? I don't want to mix in the dark . . .
2. All the recipes say to add silver to the gelatin slowly, to increase the speed. A quick dump increases contrast at the expense of speed, as I understand it.
If I like the idea of contrast more than speed, is it OK to do a quick add? How slow would that likely make the final product? Any idea?
3. There are a variety of recipes to try, each with slightly varying amounts of silver nitrate to gelatin to pot. bromide/iodide. Is there a guideline that suggests more silver is better/worse, contrasty/less contrasty, faster/slower, etc? I'm trying to decide which recipe to do first.
4. Most recipes call for thymol as a preservative. I don't have that yet. Is it absolutely crucial, or can i do a batch without it, and still expect some longevity from the emulsion? Or should I wait until I get it?