How an Exposure Calculator Can Save Your Screen Printing Shop Thousands
Myth: you can guess the perfect exposure time
Proper screen exposure is one of the most important — and misunderstood — parts of screen printing. Even experienced printers often struggle with stencil breakdown, poor detail, pinholes, reclaiming issues, and inconsistent print quality caused by incorrect exposure times.
That’s why exposure calculators have become essential quality-control tools in professional screen printing shops around the world.
At KOLORMATRIX, our free exposure calculator guide has been downloaded globally by printers looking to improve stencil quality, reduce wasted screens, and achieve more consistent results on press.
In this guide, we explain:
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why exposure times are not linear,
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how under and over exposure affect print quality,
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the differences between popular exposure calculators,
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and how to properly read your exposure test results.
We’ve also included two detailed YouTube tutorials showing exactly how to use the exposure calculator and correctly interpret the results for maximum accuracy.
Watch the Complete Exposure Calculator Training Series
Part 1 — How to Use the Exposure Calculator
Part 2 — How to Correctly Read Exposure Results
Some printers are surprised to hear that exposure times are NOT linear. By that, I mean if a screen is under exposed the emulsion and image stencil will break down or wash away. And if a screen is over exposed, nothing will washout and you will be left with a solid emulsion stencil without any image. Lastly, if the image develops into a stencil, then your exposure time is PERFECT! Sadly, this is a myth that has caused some screen printers headaches in loss production and profits.
The examples of over and under exposure listed above are indeed part of the exposure scale. But they represent the far extremes end of a bell curve. Each end of the scale is extremely under exposed on one end of the scale and extremely over exposed on the other end.
At the top of curve is the perfect exposure time, surrounded on each side starting at slightly over or under exposed then increasing to moderate and finally to extreme over or under exposure, where we can see the extreme variances of image washing out or completely disappearing.
Max Under Little Under Perfect Little Over Max Over
What does this mean?
Just because you have a screen stencil of your entire image, it doesn’t mean you have a great stencil. We can an expose and develop an entire image in our emulsion screen stencil with no visible imperfections and still be substantially over or under exposed.
Why is this Important?
Problems directly linked to UNDER exposure.
· Stencil breakdown on press
· Pinholes
· Poor edge definition
· Scumming in the image area
· Decreased EOM / stencil thickness
· Increased chance of moire pattern
· Dot gain
· Poor color reproduction in process printing
· Difficulty reclaiming screens
Problems directly linked to OVER exposure.
· Difficulty developing image area
· Loss of detail
· Undercutting, where image shrinks
· Poor registration
· Poor edge definition
· Difficulty reclaiming screens
Types of Exposure Calculators
Step and repeat exposure calculator
They are Free and you download the file and then print to create your own film positive. You can download one here.
Advantages
- Free
- Accurate as it includes density from your printer
- Features fine details and halftones
Disadvantages
- Step and repeat takes longer to use.
- Requires multiple exposures in increments
Saati 21 Step
Achieve the correct exposure every time with the SAATI 21-step exposure guide. Easy to use, just count steps after developing. Find the right exposure with one easy test, 100% guaranteed. Shop Now
Advantages
- Cost effectiveness
- Only requires one exposure
- Easy to use & read
- Small format can be used next to an image for QC.
Disadvantages
Doesn’t showcase fine lines and halftones in stencil
Kiwo Exposure Test Film
The RESOLUTION FILM in combination with the EXPOSURE TEST FILM is ideal for quickly finding the appropriate exposure range for a given screen making process. The neutral density filters on the EXPOSURE TEST FILM allow the user to perform 1 overall exposure, resulting in 10 areas with varying degrees of exposure.
Advantages
- Only requires one exposure
- Easy to use & read
- Exposes fine lines and halftones in stencil
Disadvantages
- Expensive
- Checkout our blog post on Film Density and how it impacts screen exposure.
Why Exposure Accuracy Matters
Incorrect screen exposure doesn’t just affect stencil quality — it directly impacts production efficiency, print consistency, reclaiming time, and profitability.
A properly exposed screen can help:
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improve edge definition,
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increase stencil durability,
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reduce reclaiming chemicals,
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improve halftone reproduction,
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minimize pinholes,
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and produce more accurate prints on press.
Even small exposure variances can create major problems in high-detail printing applications such as simulated process, fine-line artwork, and halftone printing.
Frequently Asked Questions
What does an exposure calculator do?
An exposure calculator helps determine the optimal screen exposure time for your emulsion, light source, mesh count, and film density.
Why is my screen stencil breaking down?
Stencil breakdown is commonly caused by under exposure, improper drying, weak film density, or incorrect emulsion coating.
Can overexposure affect print quality?
Yes. Overexposure can reduce detail, shrink image areas, and make screens difficult to wash out and reclaim.
Why are exposure times not linear?
Small exposure changes can dramatically affect stencil quality because emulsion exposure follows a curve rather than a straight progression.
Should I test exposure times regularly?
Absolutely. Changes in humidity, bulbs, emulsion, mesh, coating thickness, and film density can all affect exposure results.
What is the best exposure calculator for screen printing?
Popular options include:
- step wedge calculators,
- SAATI 21-step guides,
- and KIWO exposure test films.
Each offers different advantages depending on your workflow.
Recommended Screen Printing Products
- Exposure Units
- Exposure Calculators
- Emulsions
- Films for creating positives
- Scoop Coaters
- Aluminum Frames
- Laser Temp Guns
Other Articles of Interest
- film density article
- emulsion guides
- mesh count blog
- reclaiming articles
Looking to improve stencil quality, reduce reclaiming problems, and achieve more consistent screen exposures?
Shop professional screen printing supplies, exposure units, emulsions, waterproof film, and quality control tools at KOLORMATRIX.