Random emulsion questions

[Wildcard]

I've been wondering about a few things regarding basic emulsion practice that I haven't seen questioned yet, this probably means everyone has it dialled in already but I'm keen to know.

1. What is it that makes a diazo or dual cure emulsion expire after mixing? I'm trying to understand so that I can tell when the stuff is turning (ie. before it's totally obvious) and whether keeping it in the fridge (as was recommended to me) is helping. I use Kiwo SWR red for my dual cure.

2. Is it possible to reduce emulsion slightly with water? This sounds bizarre I'm sure, but the high solids emulsion I use is Ulano Orange and it gives me great results for thick stencils and sharp edges on art. My only issue is that it's a touch too thick and doesn't coat as easily as the Kiwo. The second thing is that it dries so fast that it can get sticky around the edges of coater and pail while in use, which causes other issues. Is there any reason I shouldn't add a touch of water and stir it in to get the ideal consistency?

3. What is the best plan for using the dregs of a pail of emulsion? I am assuming that mixing older emulsion in with a new pail is going to ruin the good stuff. Perhaps I'm wrong?
So once a particular mix is getting too low to fill the coater nicely, do I just bin it and start a fresh batch? I hate wasting chems...

Interested to know what you guys think.
Cheers
James

[ABuffington]

1. Diazo emulsions or dual cures use diazo.  Once added to the emulsion you have 4-6 weeks of optimum exposure experience.  You can stretch this to 2-3 months by keeping it sealed and storing the emulsion below 80 degrees.  Diazo starts 'baking' over 80 degrees and will become hard to develop when it goes bad.

2. Do not use a fridge.  It raises viscosity when cold, it adds water to the emulsion every time you put it back from a warm environment to cold due to condensation on this inside of the bucket.  Less than 80 is better to keep viscosity and water mix accurate.

3. Dregs: do not add to new emulsion.  If over 2 months use as block out.

4. If you do not use all of a dual cure in time, switch to pure photopolymer emulsions, (no diazo). 1 year shelf life vs 4-6 weeks.

5. Adding water will lower viscosity and may affect durability. 

Alan
Murakami Screen

[Wildcard]

Thanks Alan! Temperatures here get well over 80 in summer, so I'm assuming the fridge is the better option at those times.

[ABuffington]

If you choose to use a fridge let it warm up before using so the viscosity is correct.
Or use a pure photopolymer like Aquasol HVP that is unaffected by heat.
Or you can store in an office area that is air conditioned.