simonplowshare

Anyone had good results splitting up diazo emulsion to sensitize in small batches?

Say I really like diazo emulsion but I wont use a quart in 2 months. Assuming I have the gear to split up the emulsion, sensitizer powder and sensitizer water very accurately then can I cut everything in half and senstize in 1/2 quart batches? I'm using ulano fx-88.

Also: Is isolated sensitizer powder sensitive to light?

(ps tried presensitized Ulano QX-1 but the exposure time was way too picky for my setup: 11 seconds underexposed 14 seconds overexposed. F-that)

Thanks!

 

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Tj Ryonet Tech

My personal opinion is that it's not good to try and split up containers of emulsion. If you don't use very much try going to capillary film and just use the sheets you need at the time you need them.

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denck

Why?
Once I mix mine- I keep it in a fridge and it stays there until I need it. Never a problem with burning screens. By keeping it in a controlled envirement my emultion doesn't go through the temp changes and doesnt hit the 100 deg mark in the summer. Yes I turned my fridge up - just enough to keep a Pepsi cool but thats it.

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RichardGreaves

Quote: Originally Posted by simonplowshare Is isolated sensitizer powder sensitive to light? (ps tried presensitized Ulano QX-1 but the exposure time was way too picky for my setup: 11 seconds underexposed 14 seconds overexposed. F-that)

Yes, diazo reacts with UV energy, that's why it comes in opaque or brown bottles.

IF you decide to weigh the diazo and 'split' it, remember to work in a UV safe room with a mask so you don't breath any. Store the unused amount in a UV safe container.

You probably mean to write that your fine lines closed up/choked and you are calling 'under cutting' or light scatter, overexposure.

What was the bad thing that happened when you exposed for 14 seconds? How did you determine 11 seconds was under exposed?

What kind of a lamp do you have that can cure in less than 14 seconds with FX88, when the starting exposure on 305 mesh using a 5,000 watt metal halide lamp is 30 seconds.
http://www.ulano.com/emulsn/diazo.htm

Overexposure
Exposure can lead to fine lines closing up because of undercutting or light scatter, but when it comes to hardening the stencil, there is nothing wrong with exposing for longer than necessary - you just waste electricity and time when the stencil no longer changes.

This is not like dry overcooked food, or UV burned skin at the beach. It's like cured plastisol or concrete- you can't over cure.

Imagine your positive stopped all UV energy, you could expose for hours and all that would happen would be that eventually there would be no more sensitizer to cross link.

The stencil wouldn't change anymore no matter how long you exposed.

How long does it take to fill a 1 gallon bucket with water? Exposure is volume, not time. A medicine dropper takes 2 hours, but the firefighters next door take only 2 seconds. All you do is waste time and UV energy.

Do not confuse under cutting with over exposure! Light coming from 2 sides will choke the size of fine lines because the light falls on the positive at an angle. The only way to compensate for undercutting is to make lines and dots larger in art so they survive exposure.

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sammarino

I have successfully split 2 quarts of Diazo emulsion. I just worked in a light safe room. I used a very accurate digital scale(which I use to measure hops for homebrew) to split the powder. Make sure you get every bit out of the container before splitting it. Then you just do the same with the liquid. Just be precise. If you don't have a really good scale then do not attempt it.

 

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simonplowshare

Quote: What was the bad thing that happened when you exposed for 14 seconds? How did you determine 11 seconds was under exposed?

11 seconds washed away the emulsion, 14 seconds overhardened my positive areas. AFter reading your post, I guess this was due to UV energy penetrating my positive films. I thought they were pretty dark.

Quote: What kind of a lamp do you have that can cure in less than 14 seconds with FX88, when the starting exposure on 305 mesh using a 5,000 watt metal halide lamp is 30 seconds. Diazo Direct Emulsions from Ulano

It was QX1 Iwas reffering to there, not FX88. Overall, I found the Diazo to be much more forgiving with my exposure setup (flourecent tubes, washing out outside)

Thanks for the info on the Diazo powder. I was measuring to the 100th of a gram witha digital scale, but I probably ruined it in the light.

 

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