Measuring Yarn and Thread
The instrument illustrated below is an UltraScan VIS. Measurements on an UltraScan PRO or ColorQuest XE would be carried out in a very similar fashion.
Measuring the color of textile yarn before it is sold or woven into fabric is very important for ensuring lot-to-lot color consistency. Yarn and thread may be translucent and are directional when wound for measurement. 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 yarn should be averaged for the final result, preferably with rotation of the sample between measurements.
A HunterLab UltraScan VIS diffuse/8° spectrophotometer with the 1.0-inch area of view can be used to measure the reflectance of yarn samples wound into multiple flat layers on a card or skein holder. This method is recommended by HunterLab for the measurement of yarn, particularly when color formulation is to be carried out.
The UltraScan VIS
The Application
Yarn has several non-uniform characteristics that require compensating preparation and presentation techniques in order to ensure a repeatable sample measurement.
Yarn 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.
Yarn is directional when wound for measurement, requiring the averaging of several readings with rotation.
Yarn is flexible, and care must be taken that it does not pillow into the measurement port. It should be backed by a hard surface to become effectively a solid medium.
Yarns (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 to read using the desired color scale, illuminant, and observer. | |
| 2. Standardize the instrument for the large area of view in Reflectance - Specular Included mode using the light trap and calibrated white standard that come with the instrument. |  |
| 3. Wind the yarn around the skein holder (HunterLab Part Number 02-7396-00) or a white card in multiple taut layers until it is effectively opaque and is as flat as possible. More instructions on using the skein holder are provided in your User's Manual |  |
| 4. Place the skein holder at the reflectance port and back it with the sample clamp or a white backing tile to provide a consistent background and pressure. (If desired, you may use the port plate with glass [HunterLab Part Number A02-1011-124 for ColorQuest XE, UltraScan PRO, and UltraScan VIS] to prevent pillowing and to protect the sphere from yarn debris.) |  |
| 5. Take a single color reading of the yarn backed by the clamp or tile. Rotate the skein 90° and read the yarn at least once more. Average multiple measurements in groups of two with a 90° rotation between readings to minimize variation associated with the directionality of the sample. It is recommended that a minimum of four readings with rotation be averaged. | |
| 6. Record the average color values for the sample batch. |