7.1 Ebullition shrinkage of spinnings "S" and "HB"

For the later treatment of HB spinnings it is important to control their shrinking capacity and to determine the degree of it for each particular case. Considering that the shrinking must be real and not calculated by titles difference the following method of shrinking in hank was developed.

7.1.1 Hanks Preparation In a laboratory Hank machine ; generally around 1 meter of circumference, a minimum of 3 hanks are made.

The thread length in each hank must be the result to multiply Factor K = 8 by the Nm (for example, for a Nm 1/40: we will multiply 8 40 xs = 320 meters and/or for a Nm 2/40 we will multiply 8 20 xs = 160 meters. Is preferably, to use a Hank machine with a clock.

The hanks are marked with 4-5 loose moorings. These moorings avoid simultaneously that the hanks are entangled with each others in the boiled process.

7.1.2 Hanks Measurement, determination of the shrinking A wood is hang up on the wall, with a hook that is placed in the superior part, in which the hank subjected to measure will be hung . From its position (00 mm) a one meter length graduated rule is hang up.

Once the hank is hung on the hook, a weight of 2 kilos is placed on is inferior part to tighten it. After this, the length is taken which will be the initial length.

The state of the hanks after being boiled is not always smooth and sometimes it is necessary to disentangle them and fix them by hand. After this, the second measurement is made repeating the same procedure, which determines the final length.

7.1.3 The Shrinking Process The shrinking of the spinning takes place in boiling water. According to the existing facilities, the hanks can be treated in an device of the laboratory dyed or in a simple sufficient capacity pot.

As far as possible, watercourse will have to be reduced or avoided, and also the movement of the bath \ twirl of the hanks in the water. The hanks are hung on bars in the boiling water. It is advisable that the water contains 3 cm3/litro of formic acid v 1 gr/Iitro of Avolan IW like a moisturizer. The hanks are boiled during 30', and then slowly cooling the bath to 30 - 40°C approx, then the hanks are extracted. The drying in s! is done with air to a maximum temperature of 40°C. The speed of drying can be accelerated with a fan.

7.1.4 Evaluation Of the total longitudinal space that was determined before and after the shrinking process, the shrinking is calculated according to the following formula:

E= hank Shrinking respect to the spinning %
Li = Initial Length
Lf = Final Length

		Li - Lf
E(%)	=		x 100
		Li

The test can throw a distorted result 1 to 2% when it takes place in a pot instead of a device to dye hanks. The cause is the movement of the bath that always exists in the dyeing device or the fact that the spinning is entangled more easily in the pot.

7.1.5 Observations the experience has demonstrated that the previously described method is actually the best procedure to measure the shrinking. it stands out because of its easy accomplishment, universal application and acceptable result .

In the case that the producers use test methods different from the described here, different values from shrinking can come out. Even though the approach is big, the procedure of measurement through the difference between the initial Nm and the final Nm, does not count with the general acceptance due to the distortions that this can have because of the inaccuracy that haves the measurement procedure of the Nm.

The tractive forces that influence the spinning during the dyeing, the coling and the hanking, can cause changes in the Nm, which has to do more with the intensity of traction and the friction of the spinning. These are influenced as well by the intensified torsion and possibly by the encimaje applied after the hank dyed. Such forces can vary depending on the state and type of the machine used by the producer.