SAATI 21 Step Exposure Calculator
Compact 21-step exposure calculator that lets you dial in the perfect exposure time in a single test for any stencil type or mesh count.
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Product Details
The SAATI 21-Step Exposure Calculator is a small, highly accurate film positive that streamlines exposure testing for screen printing. By attaching it to your stencil material before exposure, you can easily quantify the cure level and determine the exact exposure needed for your setup.
It takes up minimal space on the screen and can be blocked out on final production screens, making it practical for both testing and ongoing quality control.
Key features & benefits:
Determines the exact level of exposure with only one test
Works with any stencil type (traditional and capillary/direct-to-screen) and any mesh count
Compact design that uses minimal screen area
Includes an exposure guide and correction multipliers to quickly adjust time
How it works:
Attach the 21-step calculator to the stencil material before exposure.
Expose the screen at your current time.
After washout, count the number of clearly defined steps that remain.
Use the provided guide to adjust your exposure time up or down.
Target cure levels:
For most traditional emulsions: 7 steps is the preferred cure level.
Overexposure: 8+ steps → reduce exposure time.
Underexposure: <6 steps (traditional) or <5 steps (CtS) → increase exposure time.
Exposure adjustment guide:
To increase exposure:
+1 step → multiply time by 1.4×
+2 steps → 2.0×
+3 steps → 2.8×
+4 steps → 4.0×
To decrease exposure:
−1 step → multiply time by 0.70×
−2 steps → 0.50×
−3 steps → 0.33×
−4 steps → 0.25×
Example adjustments:
10 seconds → Step 4 (underexposed) → 10 s × 2.8 = 28 seconds
60 seconds → Step 9 (overexposed) → 60 s × 0.5 = 30 seconds
30 seconds → Step 7 → perfect cure
Advanced use:
Record optimal exposure times for different products and coating thicknesses to build a reliable exposure library.
Use step results to detect inconsistencies in coating thickness when multiple stencils exposed for the same time cure differently.
Fine-tune exposure for specific jobs by selecting the step that produces the best print quality, not just the “standard” 7-step target.