CAUSES OF FAILURE There are 2 ways in which fusible interlinings can be said to fail, either: The interlining separates partially or completely from the face fabric; Wrinkling of the face fabric occurs where the interlining has been applied. Either of these faults might become evident either shortly after fusing, in wearing or after washing or dry cleaning. These faults might be caused by the use of faulty interlining but are much more frequently due to the use of incorrect fusing conditions or to the use of an unsuitable interlining. The following suggest some of the main causes of difficulties. DEFECTIVE OR INCORRECTLY ADJUSTED FUSING e.g. uneven pressure variations in temperature variations in time of fusing   INCORRECT FUSING  CONDITIONS   DEFECTIVE INTERLININGS Defects which can occur with interlinings are: The interlining is not shrink proof; The interlining has been stored too long and the shelf life of the adhesive has been exceeded.   INCORRECT MATERIALS USED The interlining itself must be compatible with the outer fabric, e.g. as a general rule, very heavy interlining should not be used with very light fabrics. The adhesive must be suitable for the intended end use. This applies particularly to its dry-cleanability and washability.