AutoCAD grayscale.ctb Explained
Understand grayscale plotting where colors become tones rather than pure black. In a CTB workflow, indexed drawing colors select color-dependent plot-style rows, so file location, drawing mode, Page Setup selection and the CTB mappings all matter.
Start here — what you are going to do
Your goal: Understand grayscale plotting where colors become tones rather than pure black.
Where to start: Open a CTB-mode drawing and have the approved CTB or standards source available.
Beginner rule: Do not edit drawing colors to compensate for a missing or wrong CTB. First check mode, file path, selected table and mapping.
Step by step — follow this in AutoCAD
Step 1 — Confirm the drawing uses CTB
Where: Command line > type PSTYLEMODE, and/or open PAGESETUP.
Do this: Verify the drawing is using color-dependent plot styles rather than named STB styles.
Check: You are troubleshooting or editing the correct plot-style system.
Step 2 — Open the active Plot Styles folder
Where: Command line > type STYLESMANAGER.
Do this: Use the folder AutoCAD opens instead of guessing a Windows path.
Check: The active CTB/STB search location is known.
Step 3 — Check the CTB used by the Layout
Where: PAGESETUP > Modify > Plot Style Table.
Do this: Confirm the exact approved CTB name selected by the Layout or batch setup.
Check: The selected table is known.
Step 4 — Apply grayscale.ctb and compare tonal output
Where: Plot Styles folder / Plot Style Table Editor / Page Setup.
Do this: Apply grayscale.ctb, Preview dark/medium/light ACI colors, check screening/lineweights and compare a physical output if contrast matters.
Check: The CTB file or mapping now reflects the intended standard.
Step 5 — Preview a calibration sample
Where: Ctrl+P > Preview.
Do this: Check known ACI colors, lineweights and screening before using a live drawing as the test.
Check: The mapping behaves as expected.
Step 6 — Verify a PDF or paper sample
Where: Plot the calibration or representative sheet.
Do this: Compare it with a known-good standard output.
Check: The CTB task is proven in final output.
Beginner example
A coordination set may benefit from tonal separation even when a construction issue uses full monochrome.
Understand what AutoCAD is doing
CTB is color-dependent
AutoCAD Color Index colors select the plot-style rows, so an office CTB workflow depends on consistent indexed-color use.
The CTB file is external
A DWG/Page Setup can reference the CTB name without carrying the actual file to another workstation.
Plot color, lineweight and screening are separate properties
A line can plot black yet still be the wrong thickness or too faint. Test the full graphical hierarchy.
Useful next guides: AutoCAD monochrome.ctb Explained · CTB Screening Explained · CTB Lineweight Mapping · Make a CTB the Standard for Page Setups · CTB Plot Styles
Common problems and what to check first
| What you see | What may be causing it | Check this first |
|---|---|---|
| CTB is not listed | Wrong Plot Styles folder or drawing is STB-mode | Check STYLESMANAGER and PSTYLEMODE. |
| Works on another PC | CTB file/version differs | Compare the controlled master and active Plot Styles folder. |
| Colors are correct but lineweights are wrong | CTB mapping or object lineweights differ | Inspect the relevant ACI row and Page Setup plot options. |
| Batch output differs from single plot | Page Setup Override selects another CTB | Check PUBLISH/Sheet Set configuration. |
When you need a more repeatable workflow
Keep the approved CTB in a controlled standards source, reference it through named Page Setups and Page Setup Overrides, and test any edit on a calibration sheet before distributing it to the CAD team.
Official Autodesk references
Interface labels can vary slightly by AutoCAD release, workspace and installed output devices. These Autodesk resources are the primary references for the workflow above.
Frequently asked questions
Does a CTB change object colors in the DWG?
No. It changes plotted behavior.
Can two CTBs have the same filename but different output?
Yes if uncontrolled copies exist; use version-controlled standards.
What is the safest CTB test?
A calibration drawing showing the ACI colors, lineweights and screening values your office uses.
Explore more in CTB Plot Styles: Complete Guide.