Fabric defects

The finished fabrics can show various kind of faults which can be ascribed to the operations which

follow one another till the realization of the finished fabric. The most common defects which

appear in more or less extended areas of the fabric are:

·         Knot

·         crease mark

·         abrasion or hole

·         tear

·         stain

·         dirt contamination

·          moirè = presence of vawy areas in periodical sequence, reflecting the light and due to a

             different compression of weft or also of warp.

·         grain = presence of designs with streaked and sinuous lines.

The most common fabric defects due to warp are:

- Faulty thread = a thread or pieces of thread which are coarse, fine, irregular owing to higher or

lower twist or to other twist direction, of different colour, with two or three ends;

- missing thread = a thread or pieces of ground or effect threads which are missing in the fabric

weave;

- tight/slack thread = a thread or pieces of thread which are tighter or slacker than the other

pieces/threads;

- incorrectly woven yarn = a thread which in some parts only of the fabric is not interlaced in the

standard way

- broken warp = small pieces of cut or missing warp thread

- reversed thread = crossed, exchanged threads or thread pieces;

- warp stripes = one or more faulty threads giving rise to zones of different aspect; it can be due

to scraping or rubbing from members of production machines or to inaccurate reeding;

The most common fabric defects due to weft are:

·    Faulty weft = a weft or pieces of weft which are coarse, fine, irregular (slubs, etc.), twisted,

   reversed, with different twist, of different colour, double weft

·   missing weft = weft or pieces of weft missing in the fabric weave

·   tight/slack weft = a weft or pieces of weft which are tighter or slacker than the other

   pieces/wefts

·   incorrectly woven weft = a weft which in some parts only of the fabric is not interlaced in the       standard way

·   cut wefts = short pieces of cut wefts

·   weft bars (starting marks) = visual light/dark effect in weft direction due to higher or lower weft density caused by the weaving machine.

The quality control on the fabrics is carried out on a special inspecting machine, equipped with

special lamps which facilitate the defect detection by the operator, marks them with labels of

different colours according to the fault type and importance.

Depending on the number of faults and on their importance, the fabric pieces can be classified as

standard (in respect to quality specifications) or can be subjected to a more or less serious

degrading with consequent compensations to the customers or with the sale of the fabric at a

reduced price.

Various defects can arise during the stages of weaving preparation (warping, sizing, threading-in

into the heddles and into the reed) as well as during weaving itself. It is therefore important to

regulate accurately the various devices of the weaving machine and to understand how to act in

case of anomalous operating situations which create defects and/or reduce weaving efficiency.