Article By: Colin Huggins
It's that time of year again. There is a bite to the air, frost on your car windows, there might even be a dusting of snow outside your front door. Why does this affect your screen print shop? Screen printers need to be conscious of both what you order and when you order it.
Both emulsion and emulsion remover can and will freeze. Most emulsions are not freeze/thaw stable. Depending on the emulsion's chemistry, you can see a number of different results when opening the container. Ross Balfour of Saati shared four facts you need to know about emulsion in the winter.
1 — Recognize that all emulsions will freeze. It's what happens when they thaw out that will let you know if it has gone bad.
2 — Emulsions that have gone bad, when thawed, have one of the following characteristics:
a: It may gel into a rubber ball or have a thick rubbery consistency that is difficult to break apart.
b: It may separate into different layers. When mixed, it will not stay mixed together. The emulsion will re-separate, exhibiting the various layers again.
c: It may feel and look grainy. You'll be able to coat a screen, but the tiny clumps in the emulsion will NOT crosslink. If you need confirmation that the emulsion is grainy, coat a single screen and see if it will properly expose.
3 — If you are using a dual cure or adding diazo, you may also see the diazo is no longer a fine powder and has turned solid. While this can happen even if it hasn't frozen, during freezing and warming the bottle could have some moisture condense within the bottle. If this is the case, the diazo has gone bad and you will need a new bottle.
4 — If you think the emulsion may be safe, mix it together until its a smooth consistency and wait 3-4 hours to see it the emulsion settles out or feels a little grainy. Test with a single screen to ensure the emulsion has not gone bad.
Don't forget about emulsion remover. While it freezes, the active ingredients can crystalize, sinking to the bottom of the container. If the emulsion remover has crystalized, warm it up to room temperature and give it a good shake until the crystals are re-dissolved into the rest of the solution.
To avoid frozen supplies altogether, order it before the weather gets too cold. If you do get a shipment during the winter, bring it into a warm space as soon as possible to help prevent freezing.
Stocking up on products is always a good idea before winter, so you know you’ll have enough emulsion to last until the weather warms up again. Think ahead and you'll save money and yourself from a headache.