The screen room is one of the most critical parts of your print shop. Get it wrong, and you’re chasing issues at every stage. Get it right, and you’re on your way to sharper prints, fewer re-burns, and more consistent results. In this guide, we’re answering some of the most common darkroom questions from printers like you, with pro tips from Kevin over at Chromaline.
What Emulsion Should I Use?
There’s no one-size-fits-all answer. The best emulsion depends on your ink system, exposure unit, and environment. For example:
- Using water-based inks? Try a water-resistant emulsion.
- Using an LED exposure unit? Go with a photopolymer like ChromaLime.
- Want better stencil build and durability? Use a high-solids emulsion.
Every shop is different. Your emulsion should match your ink, exposure output, humidity level, and workflow speed.
RELATED: Which Emulsion is Right for Me?
Does Emulsion Color Matter?
In most cases, color is a matter of preference. That said:
- Red emulsions tend to expose slightly slower but can hold better detail.
- Blue emulsions expose faster but may sacrifice fine detail slightly.
The main benefit is visibility during registration. Choose the color that works best for how you align your screens on press.
What Kind of Lighting Should I Use in My Darkroom?
The safest option is to use yellow, UV-safe lights. These block wavelengths below 475 nm to prevent premature exposure. Avoid white lights, even ones labeled UV-blocking. They often block the wrong wavelengths.
If you're using fluorescent fixtures, cover them with T12 UV sleeves or T8 sleeves.
Even under yellow lights, prolonged exposure can affect your emulsion. Light-safe doesn’t mean exposure-proof.
How Many Times Should I Coat My Screen?
The number of coats depends on your emulsion type and mesh count. High-solids emulsions like Baselayr Complete leave more behind with fewer passes. Lower-solids emulsions may need more coats to build proper stencil thickness.
Need fine detail? Use 1x1 with a sharp edge on higher meshes. Printing bold artwork? Use a rounded edge 1x1 on lower mesh for better ink deposit.
Want to test stencil build? Use a thickness gauge and aim for a 10–20% EOM target range.
How Long Should Emulsion Dry?
Here’s the rule: emulsion is ready when it’s dry all the way through. Factors like temperature, airflow, and humidity all impact dry time. A hygrometer can help you track your darkroom environment, but surface dryness doesn’t always mean it's ready. As Kevin says, think of a tomato: dry outside, wet inside.
Best practice: coat today, use tomorrow. Or, use a drying cabinet and get screens ready in 20–30 minutes depending on coat thickness and airflow.
RELATED: Darkroom Optimization 101: How Many Screens Does Your Shop Really Need?
How Long Should I Expose My Screen?
There’s no universal answer. Exposure depends on mesh count, stencil thickness, humidity, bulb strength, emulsion type, and more. To find the right time, run an exposure test with a step wedge calculator.
Test each emulsion and mesh combo. Every variable affects exposure, so don't guess, test!
Can You Add More Coats After Drying?
Yes. You can add face coats to dried screens to build thickness for high-density prints. Coat, dry, repeat as needed. But if your coat is inconsistent...say you ran out halfway through...it’s better to reclaim and start over. You won’t get even results otherwise.
When Should I Invest in an Automatic Coater?
If you're moving to an auto press, it's time to invest in a Grunig or Saati auto coater. Consistency in your coating means better results on press. Your screen room and your press floor should scale together.
Perfect prints start with a perfect stencil. Don’t skimp on the screen prep.
RELATED: Darkroom Automation Guide: Exploring the Best Options for Screen Printers
What’s the Difference Between CTS and LTS?
CTS (Computer-to-Screen) systems are typically 2-step: print the image onto the screen, then expose it.
LTS (Laser-to-Screen) systems combine imaging and exposure in one process. No consumables, no wax, no ink. Higher resolution, less dot gain, and lower long-term cost.
If you can swing the investment, LTS is the future of imaging in professional shops.
Ready to Upgrade Your Screen Room?
Dialing in your darkroom means fewer mistakes, better prints, and more time on press. If you’ve got more questions, keep learning with the links above or connect with our team directly.
Book time with a pro with our 1-on-1 services.
If you need guidance with any part of your production, it's free and you'll be able to make the next step with confidence.