9. Problems in using fusible interlining and the solutions

Correct using and manufacturing method is the base and assurance for getting ideal pressing and bonding effects. In the practical application of interlining, it often occurs some pressing and bonding quality problems concerning with the using and manufacturing method. Thus, seizing the analysis method of pressing and bonding effects, and correcting in time the limitations in using and manufacturing method, are necessary to guarantee the pressing and bonding effects.

1. Analysis of pressing and bonding effects

The ideal pressing and bonding effect between face fabric and backing fabric is flat in appearance, no fabric exuding, reaching to the standard peeling strength, no wrinkling or foaming after being dry-cleaned or washed. The above-mentioned analysis of bonding effects regularly adopts the observing and testing methods.

Observing analysis is to evaluate the pressed and bonded fabric sample in appearance changing and powder point transferring. The detailed method is as followings: After affirming the appearance of the testing sample adapted to the standard, peel the face fabric from the backing fabric and observe the destroyed bonding situation. The destruction from the central part of gel points means the destruction to the cohesion of thermosol, it belongs to the normal situation. The character is that there is complete coating on the base cloth and face fabric, which shows a proper control of pressing and the achievement of ideal bonding effects.

If the gel points are not destroyed from the central part, and there is a majority of coating leaving on the face fabric and little on the backing fabric, this phenomenon means the excess in temperature or pressure. If there is no or very little coating on the fabric, it means a shortage of temperature or pressure. These two situations belong to the abnormal destruction. Besides the improper control of pressing, they may be concerned to other factors.

Testing analysis, on the base of observing analysis, makes experiments on peeling strength, indexes of washability and dry-cleanability with the examination method, and evaluates the effects according to the results of experiments.

2. Common problems and solutions

There are mainly four problems as followings frequently appearing in the pressing and bonding between face fabric and interlining.

The main reason for the low firmness and foaming in pressing and bonding is the improper control of the three essentials in pressing and bonding, the disaccord of pyrocondensation between face fabric and backing fabric, or rosin, silicone oil or waterproof treatments of face fabric.

The improper control of the three essentials is mainly in two parts. One is excess in temperature, which is easy to make foaming the low mesh size backing fabric of the fusible gel point and the backing fabric numerous in yarn numbers; the other is due to the unsymmetrical pressure or the distortion of the pressing roller. The solution is causing a high speed in temperature and pressure.

The disaccord of pyrocondensation will cause low bonding firmness, foaming and constantly curling. The way to judging the body of pyrocondensation is observing the curling direction. If it curls to the face fabric, that means the pyrocondensation of face fabric is bigger. And for the other situation, that means that of backing fabric is bigger. For the foaming it should observe the place where the foaming occurs. If it occurs on the face fabric, it means a bigger pyrocondensation in backing fabric, and vice versa. The solution is to reselect the backing fabric or to pyrocondensate the face fabric in advance.

If the face fabric adopts rosin, silicone oil or waterproof treatments, it will directly make influence on the bonding firmness, and the fabric may not be bonded. The solution is to iron the face fabric at first, then to make pressing and bonding treatments.

Foaming after washing
After being pressed, the dry-cleanable and washable backing fabric and face fabric foam within the standard washing condition and time, this problem is due to the improper selection of backing fabric, poor bonding condition or the disaccord shrinkage rate of face and backing fabric. In addition, the shortage of thermosol coatings of backing fabric will also cause foaming after washing.

When analyzing the reasons for foaming, first of all we should observe whether the dry-cleanability and washability of the backing fabric correspond to washing limited time of the face fabric. If not, it should reselect the backing fabric.

Secondly, we should observe the character of foaming. Dry and spread the bonded fabric after washing. If we see an uneven surface and the phenomenon of curling, it means the disaccord of shrinkage rate between backing fabric and face fabric. If it curls to the backing fabric, it indicates the shrinkage rate of backing fabric is bigger than that of face fabric, and vice versa. The solution is to select the backing fabric with a corresponding shrinkage rate to the face fabric.

If the above-mentioned reasons don't exist, it should analyze whether the pressing and bonding conditions are proper or not, then retest the pressing conditions and retry the bonding treatment.

The shortage of thermosol coatings, point missing and coating leaking often cause the phenomenon of foaming. That's need to observe the quality of the coating of backing fabric. If not qualified, we should replace it in time.

Coating leaking after pressing and bonding treatments
After bonding the face and backing fabrics, if it touches hard and rough, and there are even white spots in the face fiber structure, that's coating leaking. The reason for it is the unmatching of the yarn number of face fabric with the gel point number of backing fabric, excess of coating, or improper control of pressing conditions.

For the thin or superthin face fabric, at first we will observe the gel point number of backing fabric and the thickness of coating. If the gel point number of backing fabric is relatively bigger than the need of face fabric, it should reselect a proper backing fabric. If the coating is too thick, we may reselect the backing fabric or reduce the pressure.

Secondly, we can inspect whether the setting of the three essentials of pressing are reasonable or not. Any excess in temperature, pressure or time will cause coating leaking. The solution is to select a proper pressing condition according to the melting point and melt flow index of thermosol.

Fabric adhering to the machine while pressing
While pressing and bonding, sometimes it occurs that some bonded fabrics adhere on the conveyer belt of the pressing machine. This may be due to the coating leaking, the backing fabric slice bigger than that of face fabric, the misposition of backing and face fabrics or the uncleanness of the conveyer belt.

For solving this problem, we can inspect all the above-mentioned factors, make pertinent adjusting, and clean the adhering in time. If there is thermosol on the conveyer belt, we can erase it by heating or in use of silicone oil. Pay attention to a regular cleaning and maintaining for pressing machines.