Stenter is the main process of finishing. The knitted fabric passes the mechanical action of the setting machine and the anti-shrinkage, softening and hardening of the chemical agent, so that the fabric can achieve certain shrinkage, density, hand feeling, and can achieve the appearance of uniformity of the working width, smooth lines and clear lines.

    The main physical indicators that need to be controlled
1.    Working width 
The working width can be adjusted directly on the stenter frame during production.
2.    Fabric weight
Under normal circumstances, the fabric weight is controlled by overfeed. In the case where the rest of the tension is constant, within a certain range, the larger the overfeed, the heavier the fabric weight, the smaller the overfeed, the lighter the fabric weight.
3.    Circulation 
Circulation is related to the fabric weight, which refers to the repeat size of the pattern from the start and the end. In general, the recycling is controlled by overfeed.
4.    Shrinkage
Shrinkage is one of the most important physical indicators. Shrinkage must be average. In general, the average means that the deviation of warp and weft not exceed 3%. There are many factors affecting shrinkage, such as raw material, dyeing, mercerizing, grasping, grinding, bristling and so on. 

Shrinkage is controlled by resin or by a pre-finishing.
For cotton fabric, use the resin for shrinkage. The resin is sufficiently reacted, the larger the resin, the better the shrinkage, but the problem comes with it I s that the strength drops more. Therefore, the amount of the resin is limited.

For spandex and chemical fiber, use pre-finishing for shrinkage, if necessary, use resin to assist. Pre-finishing determines the quality of the finished products. Shrinkage also related to the working width and the fabric weight. Within a certain range, the wider the working width, the larger the weft shrinkage and the heavier the weight, the smaller the shrinkage in the warp direction. Therefore, the shrinkage can be improved by adjusting the overfeed and the working width.

5.    Pilling 
Pilling is related to the raw material quality, the fabric structure, the degree of resin reaction and the pre-finishing process. There are 3 solutions to solve the pilling:
a.    Enzyme washing;
b.    With resin;
c.    Add an appropriate hard pulp;

6.    Strength 
Strength is a physical indicator that cannot be repaired, so it should be carefully controlled during the production. The strength is related to the raw material quality, the textile process, the degree of resin reaction and the pre-finishing process. Ensuring the shrinkage, pilling and distortion, need to minimize the damage to the strength.

7.    Formaldehyde content
In general, high formaldehyde content is caused by incomplete resin reaction. 
Formaldehyde content (for adult garments) is required to be <75ppm, formaldehyde content (for kid garments and underwear) is required to be <20ppm.
As long as the resin is fully reacted, the formaldehyde content of adult garments will meet the requirement. For the strict demanding of kid garments and underwear, do not use the resin finishing. If must use resin finishing to meet the other physical indicators, arrange to return to the formaldehyde washing after the resin finishing, and wet setting.

8.    PH value
The customers usually requested the PH value of the fabric be weakly acidic or neutral and the PH value of finished products not allow exceed 8. NIKE and TOMMY and most customers have strict requirements on PH value: light white PH value range: 4.5-6.5. Therefore, must pay more attention to the strict control of PH value.

    The relationship between physical indicators and raw materials and processes
1.    The raw material quality
The raw material quality affects the fabric weight, the working width, the strength, the pilling and the twisting. Under the same conditions, the raw materials thicker, the working width will be wider, the strength will be better, the surface will be smoother, the finished products will be better. The raw material twisting is higher, the finished products distortion will be better.
2.    The textile process
Within a certain range, the yarn length is tighter, the fabric weight is heavier (except spandex), the working width is narrower, the strength is better and the twisting is smaller. 
3.    Fabric dyeing and washing machine types
The fabric produced by the high temperature fabric dyeing machines, the finished products are usually narrower than the normal temperature dyeing machines and the fabric weight is heavier.
4.    The finishing methods
Mercerizing, scratching/grinding/bristling, enzymatic washing and pre-finishing will affect physical indicators.
Mercerizing has a great influence on the finished products. After mercerizing, it can have a good fabric gloss, the fabric structure is much more stable than before and the strength is also improved.

Grasping/grinding/bristling and enzymatic washing will reduce the fabric strength and the fabric weight may also decrease. For spandex and chemical fiber, the pre-finishing largely determines the quality of the finished products. Pre-finishing is one of the most important control links. Temperature, speed, fabric weight, circulation, etc must be strictly controlled, otherwise the finished products may fail to meet customers’ requirements.

    Process elements
The process is based on the state of the fabric: working width, fabric weight, the strength and shrinkage.
1.    Temperature
Resin: dark color: 170℃, light color (sensitive): 150℃
No resin: 150℃
Dry fabric: 130-160℃
100-150℃ has a little effect on the color, when the temperature is over 150℃,the temperature is higher, the affect is bigger.
2.    Speed
According to the fabric structure and thickness.
170℃ 14m/min (＞250gsm)
170℃ 16m/min (200-250gsm)
170℃ 18m/min (＜200gsm)
Under the same temperature condition, the difference of the fabric surface (0-6% moisture content) of 2-3m/min can be neglected.
3.    Circulation 
a.    The fabric with resin use grade II wind, the thermal efficiency is higher than grade I, and the effect on the color is large than grade I;
b.    The tight and thick fabric without resin use grade II wind, the loose and unstable fabric without resin use grade I.
4.    Auxiliary 
a.    Resin, catalyst and the fiber have chemical reaction, covalently bonded, changing the fiber internal molecular arrangement, has a impact on the fabric color;
b.    The yellow softener has a bigger influence on the fabric color than the white softener. Cationic softener (surfactant) have a bigger influence on the fabric color than nonionic softener.