Quote Originally Posted by sanking View Post
"When you tested the emulsion with the step wedge…. this is a step edge transparency that you contact printed onto the emulsion sample. Then you developed that and took a picture of the wedge print with a digital camera. What are the steps in the wedge… 1 stop per step? "

In this case I scanned the step wedge since it is small enough to do so, and being on smooth Yupo texture is not a problem as it can be with some papers. Each of the step wedges is log 0.15 density, or the equivalent of 1/2 stop. A full stop in sensitometry is log 0.3.

"Can you develop in warm water, or do you have to use other chemicals?"

Development is in warm water, same as with tissue sensitized in dichromate.

"Why would you want to brush on the sensitizer rather than mix it in the emulsion. To avoid marginal emulsion stability when sensitized? Or set contrast grade at print time?"

In monochrome printing I like to set the contrast grade at the time of printing, to be able to fine-tune it for a specific negative. This is the equivalent of being able to work with a variable contrast paper in silver printing, where you can fine tune contrast with filters. With pre-sensitized tissue you are stuck with the contrast that is built in.

With color my though process on this would be different as you would want to start with tissue with known and consistent characteristics.

Sandy
Ok, I understand.
Would it be possible to make pre-sensitized tissue in certain fixed contrast grades and then tune it with an additional brush coat at print time.?
That would depend on if you can get ANY sensitizer into the emulsion with brush application.