Thread charts & color index

Thread charts & color index

In printing, colors are simple – defined by pixels or vectors. In embroidery, colors are tied to threads and needles on the machine. To show designs correctly online and to stitch them correctly in production, you need to understand how Color Index numbers, Thread Charts, and Stop Sequences work together.

Colors in embroidery machines

Commercial embroidery machines have multiple needles, each threaded with a different color.

  1. A STOP command in the design tells the machine to switch to a new color.
  2. Operators map each STOP to a needle number – e.g. Needle 4 = Carmel Cream.
  3. Some designs can include direct needle numbers, but this requires strict production discipline.

Colors in Wilcom designs

Wilcom designs (EMB files) use a Color Palette – a sequence of colors chosen during digitizing.

Each color is given a 'Color Index' (0-based in XML; 1-based in the UI).

The palette itself is not tied to a specific thread brand, just a display color. API calls return this palette data so websites can render the design colors consistently.

Thread charts

Thread manufacturers promote their threads via 'thread charts', also called 'shade cards'.
 
In Wilcom, thread charts list:
  1. Manufacturer’s code
  2. Brand/type – e.g. Madeira Classic 40
  3. Color name
  4. Relative thickness, used by Wilcom for stitch spacing
  5. RGB value (for display)

Thread charts are stored in Wilcom as simple TCH text files, editable in Notepad. They are used to match design colors with real-world threads.

⚠️ Important notes for API users:

  1. The EWA API does not provide thread charts.
  2. If you need specific charts, source them from the embroidery company fulfilling the orders.
  3. Charts often need editing to remove unavailable colors – companies don’t stock every shade.

Color & thread information in API calls

Example thread data returned in XML:
<thread color="3299965" code="1876" brand="Isacord 40" description="brownish green" />
Where:
Value
Description
color
integer from RGB values (used for display)
code 
manufacturer’s code
brand
thread chart name
description
manufacturer’s color name
This information is used to:
  1. Display correct colors in EmbroideryStudio or on websites.
  2. Identify thread brand/code for production.
  3. Print production worksheets for machine operators.

Stop sequence

The Stop Sequence in an EMB file defines the order in which thread colors are used during stitching. Each STOP represents a color change, linked to a Color Index from the design. While this sequence guides the embroidery machine operator, it does not directly match machine needle numbers; operators must map colors to the actual needles threaded on their machine.

Example:

<stop_sequence>
  <stop_record color_idx="0" num_stitches="2213" />
  <stop_record color_idx="1" num_stitches="605" />
  <stop_record color_idx="2" num_stitches="2445" />
  <stop_record color_idx="3" num_stitches="2265" />
  <stop_record color_idx="4" num_stitches="313" />
  <stop_record color_idx="3" num_stitches="1768" />
</stop_sequence>
  1. The design has 5 colors (indexes 0–4).
  2. Color 3 (black) is used twice. This saves time by grouping stitching where possible.
  3. Operators then map each color index to actual needles on the machine. The order may vary depending on how the machine is threaded.
In this case the embroidery machine operator would have to select the following needle sequence:
Needle 1 → brownish green
Needle 6 → yellow
Needle 5 → red
Needle 8 → Black
Needle 3 → light green
Alert
If you upload a machine file – e.g. DST – it only contains STOP commands, not thread details. Wilcom assigns default palette colors in this case.

Key points

  1. Color Index IDs are internal references, not tied to real threads or needles.
  2. Actual thread brand/color comes from a Thread Chart, which must match the embroidery company’s inventory.
For websites:
  1. Use Color Index to display designs consistently.
  2. Use Thread Chart info only if the production center provides it.
Info
For more information, contact support@wilcom.com.