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One of the most common measure of the quality of a fabric is the number of threads per unit length in both the warp and waft directions. These are determined normally with the help of an ordinary counting glass a square or rectangular opening of specified size. However, when a great degree of accuracy in determination of picks ends is needed or the weave is too fine to be checked with an ordinary counting glass, this counting is carried out with the help of traverse thread counter.
The VGOTECH Traverse Thread Counter consists of traveling microscope fitted on basic plate having a translucent plastic panel illuminated from below. The viewing arrangement consists of the microscope fitted on a traveling carriage which can be moved over two rods with the help of a screw. The microscope has a 10 x eye piece, and achromatic object glass. Focusing is done with the help of rack and pinion arrangement.
The fabric to be tested is placed on the translucent panel, and a built in swivable gauge having openings of different lengths is lowered over it. The total number of threads in the fabric in any one opening is counted by manually operating a stroke counter fitted on the apparatus as the cross line graticule of the microscope travels over them.
The apparatus is finished in metallic painting and bright chrome plating to give it a corrosion resistant.
Length of traverse of microscope
1”, 10, 20, 50, mm
5 digit re-settable stroke counter.
IS 1963 – 1981
Methods for determination of threads per unit length in woven fabrics
Condition the sample under test to moisture equilibrium from dry side in the standard atmosphere of 65 + -2% relative humidity and 27 + -20 C temperature.
1. Place the fabric under test under the swivable gauge above the translucent panel in such a manner that the warp threads are perpendicular to the direction of movement of the microscope. Smoothen out the fabric and gently lower the swivable gauge over it to keep it pressed down.
2. Switch on the lamp. Focus the microscope by moving it up or down till the threads in the fabric are clearly visible.
3. Move the microscope in traverse direction by rotating the knurled knob till the cross wire of the microscope coincides with one edge of the selected opening to the gauge.
The opening to be used for carrying out the determination of the number of picks shall be 50 mm if the number of threads are 20/cm or less, 20 mm if the number of threads are more than 20/cm and less than equal to 100/cm, and 10 mm if the number of threads are more than 100/cm. When determining number of picks or ends per inch, the opening selected shall be 1” if the number of picks/ends are 50/inch or less, and ½ inch if the number.
4. Set the counter to read zero. Move the microscope and keep counting the number of threads it passes over by pressing the lever of the counter as the cross wire of the microscope passes over them. Continue till the cross wire of the microscope crosses the other of the opening. The reading on the counter gives the number of threads over a length equal to the length of the selected opening.
a) Determination of number of threads shall not be made within 50 mm from the selvedges, or wherever possible, within 2mm from either end of the sample, roll, or bolt.
b) Incase of fabrics having width between 10 and 20 cm the selvedge ends shall be excluded while counting. In case of narrow fabrics less than 10 cm in width all warp threads including selvedges shall be counted and the result expressed as threads per full width.
5. Repeat the above procedure to determine the number of warp threads at four other places over the sample of fabric under test. Avoid counting the same set of threads more than once.
6. Repeat the above procedure and determine the number of waft threads at ten different places over the sample of fabric under test, keeping the weft threads perpendicular to the direction of movement of the microscope.
In case of weft threads it is desirable to have at least ten readings if the size of the material under test permits it.
Find the number of warp and weft
n = N/L x 10 (or 100)
n is the number of threads per cm (or per dm)*,
N is the observed number of threads in the distance L, and
L is the distance in mm over which the number of threads was counted
For finding the number of picks or ends per inch, the following formula shall be used:
n = N/L
n -is the number of picks (or ends)per inch,
N -is the observed number of threads in the distance L, and
L -is the distance in inches over which the number of threads was counted
Find the means of all the warp way and weft way determinations, separately for each direction, and report them as number of warp or weft threads per cm (or per dm), or as number of picks or ends per inch, The mean values obtained may be rounded off to first decimal place when reporting results in threads per cm or picks/ends per inch and to second decimal place when reporting results in threads per decimeter.