Deciding on which emulsion to use in your prints can be a tricky equation; especially for beginners.
Fortunately, we re going to talk about your options when it comes to emulsions. There are two main types of emulsions, photopolymer-based emulsions (which are composed of Styryl Basolium Quaternary) also referred to as presensitized emulsions; and Diazo emulsions, which require manual mixing of a photosensitizer and contains Benzene Diazonium.
There's also a third type, known as dual-cure emulsions which contain properties of both photopolymer and Diazo emulsions; however, for the sake of simplicity we'll focus on the former two.
Photopolymer emulsions come in one container and don t require any mixing. The intricate bonds created by photopolymer emulsions make it ideal for detail work, however, it cures extremely quickly when exposed to UV light. Therefore, it can be very unforgiving especially for beginners. This type of emulsion is very sensitive to light, so much so that daylight on a rainy day can cause it to expose your image. photopolymer emulsion creates a thinner stencil, but multiple coats can be made if a thicker stencil is required. They have a shelf life of more than a year; but is one of the most expensive emulsions on the market. photopolymer emulsion offers little resistance to water exposure. Another thing to consider if you re working with this type of emulsion; you re going to need an exposure unit with a timer and a darkroom equipped with a washout booth.
Diazo emulsions require longer exposure, taking 15 minutes or more to fully cure. This is great for beginners because it allows you more room for error when curing. However, it s not ideal for detailed prints or prints that require halftones because it creates a thicker stencil. With that said, Diazo emulsions are the cheapest on the market; making it the best option for beginners on a tight budget. Keep in mind though that these emulsions only last a few months on the shelf. An old trick for storing this emulsion is to put it in a refrigerator. However, there is no concrete evidence supporting its effectiveness; if you use this method, be sure not to let it freeze. Because it is so forgiving, you can use this emulsion with an exposure unit that does not have a timer; you may also wash this emulsion off outside if you wish.
Another emulsion to consider that combines elements of both photopolymer emulsions and Diazo emulsions is dual-cure emulsions. However, this emulsion requires mixing and dries quicker than Diazo emulsions but not as quickly as pure photopolymer emulsions. This emulsion isn't as expensive as photopolymer emulsions and creates a thicker stencil.
When it comes down to it, you want to go with the emulsion your ink manufacturer recommends. You can be confident you re using the right emulsion by going with the manufacturer's recommendation. If you're a beginner, stick with a more forgiving emulsion. If you're faced with detailed design that requires a more complex exposure; refer to your ink manufacturers suggestions and you'll be on your way to quality prints. As time goes on, with more experience, like anything, you'll be better equipped to decide on which emulsions to use for your jobs. We hope this gives you a better understanding regarding your emulsion options.