Which Emulsion is Right for Me?
There are several types of emulsions out there on the market, so how do you decide on which emulsion is best for you? First, you must ask yourself a few questions:
1. What experience level do I have with screen printing? Am I a beginner, intermediate or pro?
2. What type of exposure unit do I have?
3. What kind of ink will I be using?
4. What environment will I be washing out my emulsion in?
Asking yourself these kinds of questions will help you save time and money in the long run. Once you have these answers, you can look at the pros and cons of each kind of emulsion and compare them to your resources and experience. There are two main categories: Presensitized or Diazo (mixed).
This kind of emulsion is highly sensitive and exposes quicker, has a longer self-life and exposes fine detail beautifully. The downside of this kind is that it is VERY sensitive. In fact, it is so sensitive that daylight on a cloudy day would start to expose your image. If you wash your screens out outside, your emulsion would overexpose even the blocked out areas. There is a narrow window for perfection (or error). Often as little as 10 seconds. If you are are a beginner, I would hold off on using this type of emulsion for awhile. For this kind, you will want an exposure unit with a timer and a darkroom equipped with washout booth and supplies. This kind is great to work into, but you may run into more issues if you get into this type too soon.
1. Exposes faster.
2. Longer shelf life (up to one year).
3. Great detail retention.
1. Very sensitive – not for units without timers and needs to be washed out in UV-free area.
2. If slightly over or under exposed, you will have washout issues. (It takes as little as 10 seconds!)
3. More expensive.
4. Limited resistance to water exposure. (Though Green Galaxy CryoCoat is an exception to this rule)
Diazo (mixed) emulsion requires the addition of a Diazo powder before printing. This must be mixed into the the entire base prior to opening and printing for the first time, and is often referred to as “sensitizing” the emulsion. Once mixed, this kind will last about two to three months if stored properly. The best place to store for longer shelf-life is in a fridge, but be careful the emulsion does not freeze! This kind takes longer to expose but is more forgiving. If you go over or under by 30 seconds or one minute, you rarely have to worry about it. Diazo emulsion works great with units that do not have timers and it can be washed out under UV light successfully (most of the time) without any issue, allowing you to wash out this emulsion outside. Diazo mixed emulsions are also cheaper and less of a headache for those just getting into screen printing. This type is more forgiving, while still retaining high quality and detail.
2. Forgiving on under or over exposure.
3. Can be washed out under UV light (daylight).
4. Still offers good detail.
1. Shorter life span.
2. Must to mix to use.
After figuring out which emulsion type would be best for you, the final question to answer is: What type of ink am I using?