Common Exposing Problems And Solutions

In this blog, we’ll explore the most common exposing problems in screen printing, understand their causes, and provide practical solutions to help you achieve consistent, high-quality results. Whether you’re troubleshooting existing issues or looking to refine your process, this guide will be your go-to resource for overcoming screen printing challenges.

Emulsion Washing out completely 

If your emulsion if washing out completely or partly then your screen might not be exposed enough, Meaning you need to up your exposure times. To dial in your exposure time and save yourself a lot of hassle, We recommend purchasing an exposure calculator. You can use this to establish the correct amount of time you need to expose your screen, Without the need to keep creating and exposing new screens.

Another common problem is not adding the sensitizer. Check your emulsion as some come pre-sensitized and some come with a separate sensitizer which needs to be mixed to activate your emulsion. Don’t forget to label with the date you mixed your emulsion, Most emulsions come with a 6 month life once mixed – If your emulsion is older than this, That might be why it is washing out.

Emulsion not washing out at all

Your screen is most likely over exposed. Too much light exposure can over-harden emulsion, Preventing it from washing out and revealing your design. We recommend the same as above. Use an exposure calculator to establish the correct time. Always check the emulsion you are using and that you have prepared according to instructions.

Taking too long to expose

If your emulsion is taking too long to expose, We suggest

1) check the emulsion you are using. Some emulsions take longer to expose compared to others. If you want to up your exposure times, find an emulsion suitable for this.

2) Your exposure bulbs may need changing. Depending on how long you have had your exposure unit, bulbs will deteriorate over time with daily use. If they are not working at full capacity, then your screen will take longer to expose.

Pin holes or flaking emulsion

Sometimes your screens can get pin holes or your emulsion can even flake off, this can be down to not de-greasing your screen. Always de-grease your screen, even if they are brand new. This will remove any invisible residue from production or previous print runs. It allows a good adhesion between emulsion and screen.

Your design edges aren’t crisp enough 

If you are finding your design isn’t crisp enough, There are two things you should make sure of:

1) That your positive isn’t dark enough. You’ll need to use a high quality black ink and printer to get dark positives. If your design isn’t dark enough, It will let light through during the exposing process.

2) You don’t have good connection between glass and positive. If you have a vacuum exposure unit, Then check that you are getting good suction, If not then check for holes in your exposure blanket that could be letting air in. It may be that repairing or replacing the blanket can improve your screen exposure.  If you are using a standard exposure unit, You can add a piece of foam in the well of the screen to create good contact.

We know sometimes exposing screens can be a mindfield, However following this simple steps should help you streamline your exposure processes. If you have any other exposing questions, please get in touch via email, webchat or phone (01562 829009) and one of your team can assist you.