The container of Diazo Emulsion that I have been using was mixed on Jan 13, 2008 (I write the date on the containers when I mix). I last used on some screens about 1 month ago - they were very hard to wash out. I had to use the pressure washer, but it did work.
So this weekend, I needed some screens for a new job, and I mixed up a new batch of Diazo Emulsion. I have a sink in my garage that has a regular kitchen faucet / hand sprayer. I place the screens there to coat with water - to soak in the burned design. The images almost washed out in my sink!!
That's what I do, too. However, I'm just a hobbyist at best. We do make a lot of shirts for the band, but that's about it. I do some jobs for a few outside customers, but I really don't advertise this as a business.
I'm sure if you're doing several jobs a week a qt would disappear pretty quickly. Good for you!
Terry
Quote:
Originally Posted by splathead
How much do you mix at one time? I just buy and mix a quart container at a time. That usually lasts me a month or 2.
We go through a gallon or two a month , so they rarely have time to expire. Fresh emulsion-especially dual cure- is a lot better than stuff that's been sitting.
Emulsion shelf life depends on the emulsion. I use Ulano emulsions, so the numbers I'm referencing are for Ulano emulsions.
Emulsions come in two major types; pre-sensitized and diazo. Diazo you have to mix with the sensitizer and then use. Pre-sensitized is pre-mixed and ready to use.
Diazo sensitizers generally have a shelf life of 2-3 months (in proper conditions) ONCE mixed. If they havent been mixed then you probably have 6 months at best.
Pre-sensitized emulsions (QX-1, QTX, QFX) have shelf lives from 10-16 months (in proper conditions).
Freezing emulsion is a dangerous idea. Emulsions are not (Ulano emulsions, but I assume all emulsions are as well) freeze-thaw stable. This means if the emulsion freezes, or reaches a certain temperature of cold, when it warms up, the emulsion is useless. So keeping it chilled is fine, but some emulsions are only good down to certain temperatures.
Most likely your emulsion had just gone bad after almost 9 months of being mixed. You're lucky you even got some of it out, as I know people who've used emulsion after 3-4 months and couldn't get anything out of the emulsion.
When buying Diazo emulsions it's best to buy in small quantities (quarts) because it's shelf life is so short in comparison to a pre-sensitized (QTX, QX-1) so it may go bad before you finish it, and that's wasted money.
Pre-sensitized emulsions will cost more, but the benefit is that you don't really have to worry about a.) mixing diazo
b.) shelf life
c.) wasting emulsion
The mini fridge is a good idea although the temp can be important factors. To cold and it goes bad make sure that the emulsion stays at recommended temperature.
__________________ Beckmar Ink. Screen Printing Supplies for the t-shirt printer http://www.beckmar.com
The recommended temperature for a refrigerator is 42°F - 10° from ice cream. Did you measure the temperature in your refrigerator June 1 and January 1? The simple dials that control temperature provide no feedback.
Cold does not prevent the water in emulsion from reacting with diazo.
Cold emulsion is thicker, and coats differently from emulsion at 70°F. As is warms (I hope), and dries, it may drip.
Heat is the natural enemy of sensitizers for screen emulsions. Over 90°F and you get other problems as the heat reacts with diazo.
Emulsion likes the temperatures comfortable for humans 65°F to 85°F.
Ulano diazo emulsions have a shelf life of 12 months and a pot-life of 4-6 weeks. After that, the emulsions may still work, but you need to judge exposure with a hardness measuring device like the Stouffer 21 Step Transmission Guide because the speed will have changed. Printer Information and Training for Screen Printers
__________________
How are you measuring? retired Ulano Technical Support Screen printing since 1979 - SGIA Academy Member
Last edited by RichardGreaves; December 8th, 2008 at 12:18 PM.
Hey, we have been using rlx by ulano why?? cause sometimes i think we live in the 70's 80's...our ink suplier is an order taker...we were spending $200/week on sp supplies so I googled around new guy comes in and we "sit down and eat some chicken" welll long story short we now use an emulsion with more solids,(less pressuer,faster stroke with same ink) ...totaly changed how we clean ink for on press color change...quicker better cheaper screen clean/reclain/degreese/......out with old dude in with new....jeff
Hey, we have been using rlx by ulano why?? cause sometimes i think we live in the 70's 80's...our ink suplier is an order taker...we were spending $200/week on sp supplies so I googled around
new guy comes in and we "sit down and eat some chicken" welll long story short we now use an emulsion with more solids,(less pressuer,faster stroke with same ink) ...totaly changed how we clean ink for on press color change...
quicker better cheaper screen clean/reclain/degreese/......out with old dude in with new....jeff
So? Are you going to share which emulsion and vendor you changed to?
If I knew you were using RLX, (38% solids Magenta color) I would first suggest TLX, (38% solids Teal color). Lighter color, easier to see through for registration, but exposes 20% faster.
For a modern pre-sensitized (no mixing diazo sensitizer), emulsion with 43% solids and 18 month pot life, I would suggest Ulano QLT.
__________________
How are you measuring? retired Ulano Technical Support Screen printing since 1979 - SGIA Academy Member
Hey, Will be glad to share everything we do!!!WILLNOT besmirk anyone or any company...by name
a)we are now using a premixed high solid "made" by screen process of ala. our price is 20ish%/gal less...you can feel the stencil on image side (lays down more ink tends to flood less...)strips off easier &ect.&ect. much better ...exposes faster..why wern't we using this before????ask our ex order taker why
b)we no longer do on press color changes with spray screen opener we now use ,forgot name, comes in gal and wont peel off tape during color change again ask ex order taker... oh yea 10% of the cost
c)screen cleaning used rino 210.. now use ccc citrapaste cut 50/50 with water.. cleaner faster easier ..20% of the cost... ask the ex.....
d)striping emulsion pretty much the same havent perfected raito for liquid striper 1:10-1:30.
e)stain,degrease,dehase...no more "oven cleaner" type materal use 710 3mists /side, lite scrub, pressurewash, flood,25% of the cost...ask......
OH yea when I found water base glue our ex said "I coulda told you that"...said same thing when I showed him rubber base packing tape {peels so much easier)and when he sold us several gals of white ink that you couldn't drive thru a screen....or was it ......He realy told me that screen printers don't like to share ideas or knowledge......hmmmm ....jeff
I use Lawson SBQ. I have a gallon bucket, and a cleaned out quarts sized bucket. When the quart bucket started running low, I'd use some from the gallon bucket, but pour the left-over into the quart bucket. That keeps my emulsion in the gallon bucket fresh and clean.
After a while, the emulsion in the little bucket started getting nasty, with chunks and streaks in it. I completely cleaned it out and then started over, pouring the left-over from the gal bucket into the fresh quart bucket.
I only coat one or two screens at a time. Then I put one in a black trash bag while I burn the first one. I'm planning to build a small drying cabinet.
New Emulsion Is A Good Thing! 
