CTB Screening Is Ignored or Prints Too Dark
Screened colors that should print light are appearing almost solid or much darker than the CTB standard. Start by identifying exactly where the problem first appears, then test the most likely causes one at a time. This avoids changing a correct drawing to compensate for a PDF, driver or printer problem.
Symptoms — confirm exactly what is wrong
- Screened colors that should print light are appearing almost solid or much darker than the CTB standard.
- If every object is wrong, suspect the shared Page Setup or plot-style workflow; if only a few objects are wrong, inspect their layer/color/style first.
- Pick one affected object and trace it from object/layer properties through CTB/STB to Plot Preview.
Beginner rule: Change one setting at a time. After each change, repeat the same test so you know what actually fixed the problem.
30-second triage: Look at Plot Preview. If Preview is already colored or has wrong weights, stay in AutoCAD’s CTB/STB, Plot Options, object/layer and viewport settings. Do not start by changing the PDF preset.
Likely causes — check these in order
| Likely cause | Why it creates this symptom | Quick check |
|---|---|---|
| Screening is set incorrectly | A CTB/STB screening percentage can make content too light or too dark. | Open the Plot Style Table Editor and inspect Screening for the affected style/color. |
| Wrong CTB/STB is selected | The plot style table is changing colors, screening or lineweights differently from the standard. | Open PAGESETUP > Plot Style Table and compare the selected file. |
| Viewport layer override | A viewport can override color, lineweight, transparency or plot style for one Layout view. | Activate the viewport and inspect VP Color / VP Lineweight / VP Plot Style. |
| PDF PC3/preset differs | A different PDF preset can change quality, fonts, layers and other output behavior. | Compare the current PDF PC3 with the known-good project preset. |
For the underlying setup behind these checks, use CTB Screening Explained and How CTB Color Mapping Works while you diagnose the symptom.
Diagnostic path — isolate the responsible setting
Work through the checks in order. Do not apply a fix until its diagnostic check differs from the known-good project standard.
Diagnostic 1 — Screening is set incorrectly
Where: PAGESETUP > Modify > Plot Style Table, and STYLESMANAGER when the table itself must be inspected.
Do this: Open the Plot Style Table Editor and inspect Screening for the affected style/color.
Check: If this differs from the known-good project standard, correct it and retest before continuing.
Diagnostic 2 — Wrong CTB/STB is selected
Where: PAGESETUP > Modify > Plot Style Table, and STYLESMANAGER when the table itself must be inspected.
Do this: Open PAGESETUP > Plot Style Table and compare the selected file.
Check: If this differs from the known-good project standard, correct it and retest before continuing.
Diagnostic 3 — Viewport layer override
Where: Layout > double-click inside the affected viewport > Layer Properties Manager.
Do this: Activate the viewport and inspect VP Color / VP Lineweight / VP Plot Style.
Check: If this differs from the known-good project standard, correct it and retest before continuing.
Diagnostic 4 — PDF PC3/preset differs
Where: PAGESETUP > Modify.
Do this: Compare the current PDF PC3 with the known-good project preset.
Check: If this also matches the known-good setup, use the isolation test below instead of changing unrelated settings.
Fixes — use only the fix that matches your diagnosis
Fix 1 — Correct screening
Use this fix when: your diagnosis confirmed that Screening is set incorrectly.
Do this: Open the Plot Style Table Editor, adjust the affected Screening value to the approved standard and compare a calibration PDF.
Check: Run Preview on the same test object and compare color/lineweight with the reference output.
Fix 2 — Select the approved CTB/STB
Use this fix when: your diagnosis confirmed that Wrong CTB/STB is selected.
Do this: Open PAGESETUP > Plot Style Table and choose the controlled project table. Test one calibration sheet before batch publishing.
Check: Run Preview on the same test object and compare color/lineweight with the reference output.
Fix 3 — Remove or correct the viewport override
Use this fix when: your diagnosis confirmed that Viewport layer override.
Do this: Activate the viewport, open Layer Properties Manager and reset the specific VP Color/Lineweight/Plot Style override that is causing the output difference.
Check: Run Preview on the same test object and compare color/lineweight with the reference output.
Fix 4 — Return to the approved PDF preset
Use this fix when: your diagnosis confirmed that PDF PC3/preset differs.
Do this: Select the known-good project PDF PC3 and its PDF options. Compare the same Layout before changing drawing content.
Check: Run Preview on the same test object and compare color/lineweight with the reference output.
Verification — prove the fix before full production
- Preview one known test object and one known-good object side by side.
- Confirm the selected CTB/STB and Plot with Plot Styles setting.
- Create a PDF and compare color, screening and lineweight hierarchy with the reference output.
- Only then run the full sheet set or physical plot.
Still not fixed? Use an isolation test
Plot a small calibration sheet with known colors and lineweights through the same Page Setup. If the calibration is wrong too, the problem is shared; if it is correct, return to the affected objects/layers.
Prevention — reduce the chance of recurrence
- Keep one controlled master CTB/STB and deploy the same version to every workstation.
- Use a calibration drawing with representative ACI colors, screening and lineweights.
- Document whether the project uses ACI/ByLayer colors, True Color, CTB or STB.
- Retest after plot-style, viewport-override or driver changes.
Official Autodesk references
Use these references when the interface, driver or plot-style behavior on your workstation differs from the checks above.
Frequently asked questions
What should I check first?
Start with Screening is set incorrectly. Use the quick check in the diagnostic section before changing anything else.
What if that check is correct?
Move to Wrong CTB/STB is selected. The goal is to eliminate causes one at a time, not to change several settings together.
Can a different PDF preset fix a monochrome or lineweight problem?
Usually the plot-style/Page Setup/object settings are the first place to look. Prove the PDF preset is responsible before changing it.
Explore more in CAD Printing & Plotting Troubleshooting.