Measuring Fabric Using the ColorFlex
Measuring the color of final textile fabric before it is sold or cut for sewing is very important for ensuring lot-to-lot color consistency. Fabrics may be translucent and are very often directional. Therefore, special presentation techniques are required to provide repeatable results. In general, several layers of sample should be presented to the instrument together. Also, several readings of the fabric should be averaged for the final result, preferably with rotation of the sample between measurements.
A HunterLab ColorFlex 45/0 spectrophotometer in the port-up or port-forward orientation can be used to measure the reflectance of fabric samples folded into multiple layers. This is the method advocated by HunterLab for the measurement of fabric if a LabScan XE is not available.
The ColorFlex
The Application
Fabrics have several non-uniform characteristics that require compensating preparation and presentation techniques in order to ensure a repeatable sample measurement.
Fabrics may not be completely opaque and may look different when backed with differently colored samples. Using a sufficient sample thickness and a sample backing will minimize these effects.
Fabrics are usually directional, requiring the averaging of several readings with rotation.
Fabrics are flexible, and care must be taken that they do not pillow into the measurement port.
Fabrics (particularly white ones) may be slightly fluorescent, which means that they will be sensitive to the UV content of the light source.
| Recommended Color Scale | CIE L*a*b* or CIE L*C*h as a full color descriptor |
| Recommended Single-Number Indices | DEcmc for indication of total color difference, Shade number for dividing multiple samples into shade groups |
| Recommended Illuminant/Observer | D65/10°. C/2° may also be used. |
Measurement Method
| 1. Configure your software or the instrument firmware to read using the desired color scale, illuminant, and observer. | |
| 2. Standardize the instrument for the large area of view using the black glass and calibrated white standard that comes with the instrument. |  |
| 3. Fold the fabric into multiple layers until it is effectively opaque. Four layers (two folds in half) are usually sufficient. |  |
| 4. Place the fabric at the sample port and back it with the sample clamp or a white backing tile to provide a consistent background and pressure. If necessary, pull the fabric taut and back around the sample clamp or tile to ensure that it does not pillow into the port. (If desired, you may use the port plate with glass [HunterLab Part Number 02-6624-05] to prevent pillowing and to protect the inside of the instrument from fabric debris.) |  |
| 5. Take a single color reading of the fabric backed by the clamp or tile. Rotate the fabric 90° and read the fabric at least once more. Average the multiple color readings for a single color measurement representing the color of the lot. Averaging multiple readings with rotation between readings minimizes measurement variation associated with directionality. | |
| 6. Record the average color values for the sample batch. |