What is Water proofing

Water Proofing

Water proofing is nothing but preventing the passage of both air and water through a fabric.

Purpose

For certain uses such as Tarpaulin, Umbrella cloth, Rain coat fabric etc. it is required to give this type of finish as these type of fabrics are generally used against the air and water in the normal life. So they should have  some property to prevent both air and water  passing through them. This finish makes the wearer feel uneasy and uncomfortable as the air circulation is not there

PRINCIPLE 

A finish on the surface of the fabric should be formed for the prevention of air and water hen a uniform coating o suitable substances such as rubber is produced on the surface of a fabric. the interstices between the warp and weft yarns are blocked by the continuous film or substance and both water and air will not pass through the treated fabrics. It is a chemical and property giving Finish

Requirement

The fabric should not become unnecessarily stiff and the fabric should have soil release or soil repellent property.

The fairish should not alter the fastness properties or dyed material, feel, strength etc., of the fabric

 Method

By 2 methods, it can be carried out.

1. Methods by which hydrophobic    substances are deposited on the cloth

2. Methods by which the fabric itself becomes hydrophobic

Chemical use

1. Vulcanised natural rubber

2 Oxidized oils of varnishes

3 Polyvinyl chloro acetate.

4. Polyvinylidine Chloride

5. Cellulose acetate.

6. Cuprammonium hydroxide solution

PROSESS

 (A)The simplest method of water proofing is it coating of fabric with rubber as a thin film

DISADVANTAGE

1 unwanted stiffness and harshness.

(B)The application of Natural oil will also produce this finish.

ADVANTAGE

No cracks or brittleness

Disadvantage

it is not permanent.

(C) Coating of Water Impermeable substances like pitch asphalt and molten waxes produce water proofing

Advantage

 It will give excellent

Disadvantage

Many desirable properties of the fabrics will be destroyed

(D)Using Synthesis Resins we can produce this finish.

E.g. Polyvinyl chloro acetate

       Cellulose acetate

        Polyvinylidine chloride

( E) Water proofing with Wax Emulsion. It can be applied on cotton, linen, wool, silk fabrics. Aluminum Acetate is used along with the wax emulsion. There are two steps involved in producing this finish

First Step

Wax emulsion – 1-3 kg

Water    -    50 litter

Pad the material with the wax emulsion solution.

Second step

 In wet condition

 Aluminium acetate 1-3 kg

 Water                 -    50 liters

 Impregnate the fabric and squeeze thoroughly Then dry the fabric in a tenter or on a drying range at 110-120°C 

PROCESS SEQUENCE

Pad – dry - Calendar