Pre-Shrinking Finish on Fabrics

This is a generalized form of opinion which clearly indicates that without proper shrinking, these fabrics truly cannot be used to make garments. In fact preshrinking can only reduce the residual shrinkage to a lower percentage, but cannot completely eliminate it. Following are the measures one must take about the balance of residual shrinkage:

• On cotton fabrics, we can usually take away 8-10 %shrinkage by preshrinking, leaving about 5 - 6% in them. If you really do a good job on shrinking, you may bring it down to 4% which is generally accepted in the trade.
• On rayon fabrics we should know by normal preshrinking process alone it is difficult to bring the shrinkage down to 4-5 %as by nature, rayon fabrics tend to shrink each time you wash them in the first several washing. That is why people use the method of resin finish to try to control the shrinkage, or use Dry clean only on the care label to avoid the big shrinkage caused by washing. However both of these methods are not satisfactory because of the following
• When you apply resin to the fabric to stabilize the fiber, you may achieve better residual shrinkage, but the fabric will be less dray (not as soft). Besides the resin may be washed away slowly in a few washing and then the fabric will start to shrink again.
• When you see dry clean only on the care label consumers may not buy the garments as it is too expensive to dry clean by a commercial laundry.
• However of late a beater method has been worked out to pre-shrink the fabric starting from desiring and bleaching. As a result after dyeing or printing, we can use the normal pre-shrinking process to control the residual shrinkage to be about 5-6 % which should be the acceptable level.
• Therefore, when we order rayon fabrics, it is important that we discuss the possible shrinkage problem with the mill to make sure he knows what to do to control the shrinkage.

Ramie and Ramie/cotton blend:

Shrinkage on 100% Ramie and Ramie/cotton blend is mild and controllable. Normal preshrinking can bring the shrinkage down to 3-5 % which is an acceptable level.

Wool and Wool Blend

Wool is generally not suitable for washing particularly in hot water. If you wash it in hot water, it may shrink up to 30% depending on the construction of the fabric. If wool is mixed with some other fibers, the shrinkage may improve. Therefore, for wool fabric or fabric with wool content, you should consider the following:

• For 100% wool or wool as major content, you should use dry clean only in your care label.
• On polyester/wool or acrylic wool, usually washable in cool water. The care instructions should be worded similar to the following:
  • Machine wash cold tumble dry low.
  • Remove while it is still damp.
  • Use line dry or lay flat to dry.
  • Dry cleaning recommended.

From the above, you will see that because there is wool in the fabric, a lot of consideration has been given to the wool content in order not to make the wool content shrink excessively.

Other textile materials

We should be very careful of the shrinkage of leather. Leather shrinks tremendously if washed and dried by heat. When leather is used in garments, as trim or even as a patch, you must not wash the garment and dry it in tumble dryer till it is 100% dry. If you do the leather part will shrink out of size and become thick and stiff. You must wash it in normal way, but dry it up to 80% and air dry the balance 20% without heat.

Shrinkage in garments is very important issue because when they shrink out of size, they cannot be worn. Before pre-washed garments became popular, the shrinkage problem was even a bigger one. To tackle the shrinkage problem, a process to pre-shrink fabrics before making garments was invented by an American, Stanford L.Cluett. He registered a trademark "SANFORIZED" to signify that the fabric used in garment has gone through a registered process and the garment is shrinkage controlled (Residual shrinkage about 1%). He advertised the trademark "SANFORIZED" to build up the demand from the consumer level for "Sanforized" garments so that the textile mills and garment makers want to use the Sanforize process and the trademark "sanforized" on the garment label to make the merchandise more appealing to consumers. Of course a royalty has to be paid to the Sanforize Company for the use of the trademark.

The above is the brief history of the Sanforized trademark which is internationally known and is still used in the garment industry. However, now days you do not see this name too often on the garment labels, because most garments are now pre-washed where shrinkage problems do not exist.

Resin finish is to stabilize the fiber to make it shrinkage and crease resistant. We usually consider applying resin finish on 100% cotton fabrics (mostly knits) or 100%rayon woven fabrics because shrinkage of these 2 kinds of fabrics is hard to control, and therefore we consider to resort to resin finish.

Resin finish is not too popular now days because the resin applied will eventually be washed off. Garment buyers therefore, rather use garment wash to get rid of the shrinkage and at the same time get a washed look on the garment which is desirable.