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Compression vs. Vacuum Exposure Units

Thinking about getting a new exposure unit, or are you ready to upgrade your current unit? Many different kinds of exposure units exist, but let's look into one angle — compression and vacuum exposure units. We'll decipher the differences between the two, how to determine which one is best for you, and other darkroom details.

WHAT IS A VACUUM EXPOSURE UNIT?

The purpose of the vacuum is to create the best, tightest positive contact between the light source, glass, film, and emulsion. Having tight, strong contact to the point where the black ink in the film is almost embedded into the emulsion means that light cannot wrap around the film positive very well. The end result — a straight, clean burn with sharp edges. Vacuum units provide the best detail resolution. 

Pro Tip: Bulbs also play a huge factor on exposure results. Check out this article to learn more on that topic.

rxp led exposure unit

The RXP LED Exposure Unit

WHAT IS A COMPRESSION EXPOSURE UNIT?

Compression exposure units require a bit more work. To replicate the downforce of a vacuum unit, you'll need to put weight on top of the lid or foam to put compression onto the film, screen, emulsion, etc. in order to create the tightest contact possible. Compression exposure units will not achieve the same level of positive contact as vacuum units, but they still do a good job. Edges may be a little rough from time to time, but the stencil will still rinse out well and produce an acceptable print. For best results, printers should use emulsions with diazo. The diazo is a resolution and detail enhancer, it helps sharpen edges. Diazo solves all exposure problems issue.  

person aligning film on screen

THE TYPE OF ART YOU PRINT AFFECTS WHICH UNIT YOU NEED

Halftones, CMYK, sim process, and highly detailed prints will need a vacuum exposure unit. To capture those tiny, tiny details, you require the most tight positive contact between the film and the screen. The vacuum will achieve the best results for these kinds of prints.

Compression exposure units are best for spot color prints like block text. If you want to produce a print with a bit more detail, make sure to use diazo-mixed emulsion. 

YOUR BUDGET

A huge factor in deciding which unit would be best for you is your budget. As you could imagine, vacuum exposure units are more expensive than compression exposure units. If you'd like to get a vacuum unit but don't have the funds for it right now, buy the cheapest exposure unit you can get away with so you can save money to buy better unit later.

CHECK OUT THE FULL LINE OF EXPOSURE UNITS

printer cleaning a screen in a washout booth

YOUR DARKROOM MATTERS

In the end, it doesn't matter if you have a vacuum or compression exposure unit if your darkroom does not have the optimal environment. The darkroom needs to be as dry as possible and light safe. If you need some tips for creating the perfect darkroom, here are a bunch of blogs and videos we've covered on the topic:

Screen printing starts and ends in darkroom. The environment is just as important as the equipment inside it. The better the screens are, the easier it is to print. Invest in equipment that fits your budget and your printing needs. As always, please reach out to us if you have questions about which exposure unit would be best for you. Email us at sales@ryonet.com or call at 1-800-314-6390.
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