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emulsion turned to jello in 21 days???

5K views 22 replies 9 participants last post by  sben763 
#1 ·
Hi Guys,

I mixed up a quart of diaz emulsion with the right amount of distilled water on 7th April 2012.

I left it overnight then used it to coat a couple of screens. All good so far and the screens washed out beautifully.

The emulsion has been kept in the dark room with the lid on all this time and I only use yellow bulbs. It has not been opened since I sucessfully coated and used the last 2 screens.

So why has my emulsion turned to gloop? I tried to pour it into my coater and it all plopped out the container. Kinda like stretchy gooey silicone. Totally unusable.

Any ideas?

Thanks,

Richie
 
#7 ·
Anyone else had this happen to them before?

The distilled water was a new bottle, too
I atually had this happen last year. Perfectly good emulsion. It was about half way through. Coated screens one day. Couple days later it was thick and lumpy. I stirred it. Didn't help much but I was able to coat a few screens and it actually burned.

Have no idea what happend. It was kept cool, dark and closed tightly.
 
#5 ·
I've never had that happen to me before. I keep my mixed emulsion in a cool closet in my basement or in the fridge. I have emulsion that is almost 2 years old that is still liquidy, though I wouldn't use it for emulsion, it works fine for red out. I'm thinking it's the heat. It needs to stay cool and dark.
 
#8 ·
Arrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrgh SOMEONE PLEASE STAB ME IN THE EYE WITH A WOODEN MIXING STICK - A second pot of emulsion just glooped on me again!

Mixed on 30th April. Just checked it today - 19th May - I'm sure it's evolution in progress. If I left it any longer, I'd have mini Pterodactyls flying out the pot when I took the lid off and the emulsion would surely have grown legs and walked out the dark room.

It only happens once it has been activated. I just opened my last unmixed pot on the shelf and it looks like normal.

I mixed the last pot I have today for 2 rush jobs - not going to risk it, I'm coating every degreased screen I have tonight!

I'm going to re-stock with dual diaz, but also buy a quart of pre-mixed QT and see how that goes on the exposure and storage front.

I'm also going to take the emulsion home and store it in the fridge - We have a storm system coming in over the next 4 days or so, so the humidity may go a bit ballistic. I guess I'll have to take the emulsion to work like a packed lunch!

Hoping for a break in the rain, so at least I get to go kiteboarding to relieve some stress and get the adrenaline pumping :) Epic conditions here when it blows :)

Richie
 
#9 ·
Unmixed, it can only sit on the shelf for a few months, I think 3 - 6 months. Mixed maybe 3 months if it is kept cold and dark. I have emulsion that I mixed back in 2010 that is still liquid. Can't be used as emulsion any more but it still works as a red out substitute.
 
#17 ·
Unmixed, it can only sit on the shelf for a few months, I think 3 - 6 months. Mixed maybe 3 months if it is kept cold and dark. I have emulsion that I mixed back in 2010 that is still liquid. Can't be used as emulsion any more but it still works as a red out substitute.
I've always heard a little over a year, but they like to make date codes pretty archaic so we don't know what's up without calling them. Which, speaking of, have you tried calling the manufacturer Richie? I know Kiwo and Ulano have knowledgeable reps who are ready to help you out, and can only hope any other manufacturer is willing and able to do the same.

I get the feeling your place is getting too warm. I've never seen huge changes in emulsion because of humidity--I've printed in 10% RH, and 90% RH. (Not to say they can't happen :))
Huge changes in burn time, stencil detail, and durability, yes, but huge changes in the consistency of the emulsion, no.
 
#10 ·
i hear about this periodically but have never had it happen to me...the only thing that i can conclude is that either the emulsion was not chemically mixed properly from the factory or something accidentally got into it...either when it was made by the manufacturer or being mixed by us...although the manufacturer will place all the blame on the way it was mixed by the purchaser...i have never had any problems with saatichem...that is the brand of emulsion that we use. later dude
 
#11 ·
huh - interesting. I only ever use a brand new bottle of distilled water to mix each quart with. I'm kinda known for my ridiculous attention to detail round here. Sometimes it feels like a curse :)

Of the 4 quarts I bought, 2 went bad. The first was absolutely fine. Waiting on the fourth.......


Coated a bunch of pre-degreased screens this evening, so at least I should have enough to keep me going until the next order arrives

I plan on getting a temp/humidity data logger installed at some point too. Figured it will probably come in handy as I get busier and need more control!

Richie
 
#15 ·
i do a lot of work in the Dominican Republic. I've setup a friend down there to do some work for me, as it's cheaper than shipping.

the first two gallons of emulsion he mixed, solidified in only a few weeks.

and i knew everything was setup properly, because i did it.

i took the emulsion there myself, mixed it myself and showed him how. same emulsion as i use.

he stored his on the shelf. only a few weeks and it was trash. (i did not not know about fridge storage yet)

when i learned about it, i suggested the fridge..

now we both store in the fridge. and have no problems. up here i go through a gallon fairly quickly. but down there, not so fast. so it stays rather well in the fridge.

in both locations, i have a smaller pint sized black container. i'll pour from the cooled gallon, into the smaller container.

let it sit and come to room temperature before coating the screen.

don't coat a screen when the emulsion is cold.

takes about an hour to get to room temp. probably less for you during the warmer season.
 
#16 ·
if you are fairly new.. i will tell ya.. as you are getting into humid season now, GET A DEHUMIDIFIER and build a drying box for your screens, if you don't already have one.

worst case, get a space heater WITHOUT A FAN.

once you coat your screens, the act of them "drying" is the water evaporating from the emulsion.

if it's humid, the screens will never properly dry, because the air around them is wet.

they may feel dry to the touch, but the center won't be.

this will create problems with washout.

i know we all hate spending money. but trust me. in your environment, you NEED a dehumidifier for those screens.
 
#20 ·
Thanks for the input, Jay. That kinda reassures me - DR is pretty local on our global weather scale. Nice idea to warm up the emulsion first. Guess I need a yellow filter on my fridge light at home now! ;)

One of the reasons I boxed in my drying rack was incase I needed to control the humidity.

Thanks to everyone else too. The pot of emulsion is now chilling in the fridge, next to the eggs!

Will update this post with the results.

It's now raining sideways - probably will do for another day or so!

Richie
 
#22 ·
Hi Guys,

Just an update to the post and your really helpful suggestions.

The gloop problem is now totally resolved :) I finally scraped the funds together tobuy a refridgerator for the shop. I lost another pot and then decided that at the rate I was loosing new pots of activated emulsion, I would have paid for a new fridge in less than a month, without the hassle of having to re-order new pots of emulsionand the pressure of never knowing if I would have good emulsion for the next job! It's a really small one - enough to keep 3 or 4 quarts on the top shelf, maybe 12 0.5 liter bottles of water in the bottom and some Redbull and Gatorade in the door. I keep it at the warmest temp setting and that still allows me to use the emulsion straight from the fridge, if time is against me.

I've not had any glooping since - I'm a very happy fella!

I'm going to invest in a dehumidifier and hygrometer - even when my screens are dry, they often stick the the glass of the exposure unit (leading me to believe they are not really dry). Recently, during a coat with the more rounded side of the scoop coater and some humid weather, EVERYTHING stuck to the screen! Positive had to be ripped off and the screen almost levered off the glass. Thought I was going to rip the mesh off the static!

As demand has grown, I also need a faster turnaround of screens. I'd love to be able to coat and use screens in less than an hour, so I'm going to get a high capacity dehumidifier and a wireless hygrometer to see what I can achieve.

Once again, thanks for the help and suggestions

Richie
 
#23 ·
The dehumidifier will help. If you have a dry box you can duct the exhaust air in to box. My commercial dry box had a dehumidifier built in and it went bad. I built a sheet metal plenum and put a 6" round duct in to the dry box and still let some air blow into the shop. I added a fine filter material to dehumidifier so that no dust gets on screens. After degreasing or dehazing screens I use a shop vac with a crevis tool and blow the water off the screen. The shop vac has never been used and has a wireless on off switch. It also came with a filter that can be used on the intake side as well as the filter inside so no dust get on screens.
 
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