Unit 3 Lecture 20 Topic 4

Question 1

Textile Finish:

Answer 1

A finish is any process done to fibres, yarns or fabrics either before or after fabrication to change the appearance, handle or performance. Most often, fabrics receive finishing treatments but sometimes yarns or fibres may undergo treatments before being made into fabrics. Some finishing stages may occur before fabrication and after fabrication more finishing may be carried out.

Question 2

What are the ways textile finishes can be classified in terms of how long they last?

Answer 2

They can be permanent, durable, temporary, or renewable finishes.

Question 3

Calendering:

Answer 3

A mechanical finish where fabrics are passed between a series of rollers (some of which are heated). This produces smooth and lustrous fabric surfaces with a more supple hand. It can also make fabrics more compact (opaque) by applying heavy pressure. Calendering is durable when resin is added or applied to thermoplastic fabrics.

Question 4

Embossed fabrics:

Answer 4

Produces a raised design or motifs that result from pressing fabric between engraved rollers on an embossing calendar. Embossing influences the appearance of the fabric.

Question 5

Moire Fabrics:

Answer 5

Moire fabrics have a wavy or watermark design. A moiré finish is given to unbalanced, plain-woven fabrics that have crosswise ribs. True moiré fabrics are when two rib fabrics are placed together and then the fabrics are fed through a calendar with heated rollers and pressure. An alternative method has rib fabric embossed with a moiré engraved pattern.

Question 6

Napping:

Answer 6

Napped fabric has a thick layer of fibre ends protruding from
the fabric surface. The fibres are brushed up from the surface of the fabric with wire brushes. This napping can be on only one or both sides of the fabric, and it helps increase thermal insulation.

Question 7

Sueding:

Answer 7

Sueding is applied by sanding the fabrics. This abrasion causes fibrils to split from the fibres and produce a soft, suede-like fabric.

Question 8

Chemical Finishes:

Answer 8

Chemically finished textiles are textiles that have been subjected to chemical compounds. The chemicals may adhere to the fibre surfaces and form a barrier or coating or they may be absorbed into the fibre, where it may or may not react with fibre polymers.

Question 9

Burn Out:

Answer 9

A finish applied to influence the appearance of fabrics. Designs are produced on blended fabrics (eg. polyester/cotton or nylon/silk). Chemical reagents are printed onto the fabric and the natural fibres are destroyed as a result.

Question 10

Plissé:

Answer 10

Refers to the crinkled or puckered surface design which has been achieved by applying a chemical finish (sodium hydroxide) on fabrics. Fabrics shrink in the areas that are printed due to swelling of the cellulose fibres which causes puckering in the adjoining areas.

Question 11

Why are wrinkle resistance and durable press finishes applied to cellulosic fibres?

Answer 11

To improve the appearance during use and make fabrics easier to care for.

Question 12

How are chemical finishes applied to cellulosic fibres?

Answer 12

Chemicals react with adjacent cellulose molecules and form covalent bonds (crosslinks) between cellulose chains. These finishes are also used to set in pleats, hems, or permanently flatten (e.g., table cloths).

Question 13

Permanent Set Finishes on Wool:

Answer 13

When sharp pleats and creases are permanently inserted into wool fabrics. Alternatively, fabric can be set to be flat and remain unwrinkled during use. Permanent setting is a result of a chemical process in which the disulphide bonds are broken and reformed in a new position, and then chemically set in. It is a similar process to “perming” hair.

Question 14

Control Shrinkage:

Answer 14

Washable wool fabrics are fabrics which have been given a chemical treatment to control or prevent felting shrinkage.

Question 15

Chlorinated Wools:

Answer 15

When the scale structure of wool fibres is removed due to degradation with chlorine.

Question 16

Chlorinated/resin wool Treatments:

Answer 16

Wool is treated with chlorine and then coated with polymer resin in order to help fabrics retain their hand and strength.

Question 17

Spot-welded Fabrics:

Answer 17

When a resin binds the fibres together at points along their lengths. This is only applied to fabrics, not fibres or yarns.

Question 18

Mercerization:

Answer 18

When a strong solution of sodium hydroxide is applied under tension in order to swell cotton fibres to produce permanent changes. Mercerized fabrics and yarns dye to brighter and darker shades and are more lustrous. Polymer chains in mercerized cotton are more aligned and the fibre cross section is rounder which enhances strength, stiffness and absorbency of cotton.