# Emulsion Shelf Life



## tryplecrown (Jan 24, 2007)

I've been printing for about 6 months now and recently ran in to something I just got a handle on and wanted to share to hopefully spare someone else the frustration. I recently ran in to my stencils washing out after burning screens. At first it was subtle, just enough to create a handful of pinholes, then more, then it just felt like every screen was underexposed. I burned one the other day for twice as long as I normally burn and it still washed out. Long story short, the gallon of emulsion I was using was old and was no longer effective. I got a new gallon in last night, mixed it up, let it rest, coated screens, and this morning it's absolutely amazing how perfect these screens are burning and washing out.

I was literally to the point of not wanting to print because the issues of washing out screens was making it so stressful. But with a fresh gallon of emulsion, I feel like things are new again. 

Just for the record, we use Ulano's Proclaim CL with dye. Our supplier told me that the expected shelf life from the time the diazo is mixed in is about 4 to 6 weeks and they said it needed to be kept in a cool place and recommended trying to refrigerate if possible. Well, the gallon we were having problems with had been sitting in the garage (here in Texas) and we have been using out of it for about 3 1/2 to 4 months now. And for any newbs reading this, they have also recommended not allowing your white inks to be kept out in a hot area. 

Anyway, I just thought I would share this info in hopes that it might help someone else just starting out and not let this be a hurdle that baffles you like it did me. That's pretty tough when you don't change anything and things start changing on you.


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## pacific (Jun 16, 2007)

There is information in the carton about storage of emulsion but being a guy I didn't read it and also learned the hard way. We keep it in the refrigerator and can last 3 - 4 months, at room temp. it's good for about a month once mixed.


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## RichardGreaves (Nov 7, 2006)

Diazo sensitized emulsions start to age when you mix the sensitizer with water and the time clock starts ticking. It's the water that works on the diazo and putting the emulsion in a refrigerator does little to slow down the breakdown of the diazo.

Beware that cold emulsion will coat thicker than room temperature emulsion and when the coating warms up it may drip.

The reason you are instructed to let the freshly mixed emulsion sit to let the bubbles go away is not because you stirred it, but because the diazo is giving off gas because it came in contact with water. 

One way to avoid coating with spoiled emulsion is to switch to a pre-sensitized emulsion that has a wet shelf life of up to 18 months. They may not reclaim as well as Proclaim, but you can save money by buying in bulk for the year and never mix or wait again.


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## dfalk (Apr 11, 2007)

I use Ulano's QT emulsion for water based and plastisol printing. Is the shelf life still approx 6 months? This emulsion is pre-mixed when I receive it and should I be refrigerating this? 
There is no info on the bucket about storage or life expectancy.


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## RichardGreaves (Nov 7, 2006)

dfalk said:


> I use Ulano's QT emulsion for water based and plastisol printing. Is the shelf life still approx 6 months? This emulsion is pre-mixed when I receive it and should I be refrigerating this?
> There is no info on the bucket about storage or life expectancy.


Do you mean Ulano QTX or QT-Discharge?

QTX is a pre-sensitized SBQ textile emulsion with very little water resistance. Because it is an SBQ, it has an 18 month shelf life. Don't use this for water based inks.
Pre-Sensitized Emulsions for Screen Making Products

QT-Discharge is a dual-cure diazo sensitized emulsion with excellent water resistance that will stand up to runs of at least 40,000 prints *if properly exposed. *Once you add the diazo to the emulsion, you should coat in less than 30 days. Dry, the stencils are good for another 4 weeks. Like milk and lettuce, they spoil when the diazo is broken down by the water in the emulsion and after a while, they don't have anymore nitrogen gas to give up and crosslink the polymers in the emulsion.
Water Resistant Emulsions from Ulano 925WR QT-Discharge TZ


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## dfalk (Apr 11, 2007)

RichardGreaves said:


> Do you mean Ulano QTX or QT-Discharge?
> 
> QTX is a pre-sensitized SBQ textile emulsion with very little water resistance. Because it is an SBQ, it has an 18 month shelf life. Don't use this for water based inks.
> Pre-Sensitized Emulsions for Screen Making Products
> ...


Thanks Richard for your help. I am using the QTX emulsion. An 18 month shelf life is good to hear. After digging for the original shipping box, the box says to keep emulsion below 85 degrees F. but above freezing, so I guess I will throw it in a refrigerator.


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## RichardGreaves (Nov 7, 2006)

dfalk said:


> After digging for the original shipping box, the box says to keep emulsion below 85 degrees F. but above freezing, so I guess I will throw it in a refrigerator.


Please don't. Refrigeration will keep the emulsion at 38 to 45 degrees F and it will be very thick at that temperature. If it says that on the label, I will change it tomorrow. If you coat at 45F, you will put more on the mesh, and as it warms and dries, the coating may warm and drip.

Yes, prolonged temperatures above 100F can damage coated screens, but in the liquid state, the water in the emulsion protects it. If the bucket is sealed, where could the water go. 

QTX will not spoil like milk - just add a thin clear food wrapping plastic (Saran?) before you put the lid on the the bucket with so the lid is not hard to remove because the emulsion on the lip was sticky.


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## dfalk (Apr 11, 2007)

RichardGreaves said:


> Please don't. Refrigeration will keep the emulsion at 38 to 45 degrees F and it will be very thick at that temperature. If it says that on the label, I will change it tomorrow. If you coat at 45F, you will put more on the mesh, and as it warms and dries, the coating may warm and drip.
> 
> Yes, prolonged temperatures above 100F can damage coated screens, but in the liquid state, the water in the emulsion protects it. If the bucket is sealed, where could the water go.
> 
> QTX will not spoil like milk - just add a thin clear food wrapping plastic (Saran?) before you put the lid on the the bucket with so the lid is not hard to remove because the emulsion on the lip was sticky.


 
Then I won't be purchasing a small refrigerator for the emulsion. Thanks again for your help Richard. I do appreciate it.


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## tryplecrown (Jan 24, 2007)

Hey guys, just a follow up to this thread. I also spoke with the rep from my ink manufacturer, and he recommended Ulano's QTX also. One of the reasons for his recommendation was the extended shelf life. But also, it has a higher solids content, and I was asking about thicker stencils for printing white inks. Good info everyone!


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## KoalaTees (Jul 25, 2007)

Lots of good info here. I have purchased the two part mix and kept if for months to realize I was have problems too. So I will try the ULano QTX. Question will it last long once dried on the screen? How long can I keep them in my dark screen box I just built if I use the QTX?


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