water proof and water repellant finishes

8/2/2019 Water Proof and Water Repellant Finishes

1/10

WATER PROOFING AND WATER

REPELLANT FINISHINGPresentation by:Neelkanth

Rishav Raj

DFT-VI

Batch-09-13NIFT, CHENNAI


2/10

Water Proofing

Water proofing is the process in whichthe interstices of the fabric as well as thesurface of the fabric is covered with a film

or skin in such a way that the treatedmaterial is not only water repellant butalso impermeable for air and moisture.

Water proof fabrics are of three types:

1. Coated2. Laminated

3. High density woven fabric.


3/10

Water Repellant Finishes

Water repellant finish is the process inwhich fabric is made repellant to water by

coating it with hydrophobic material, or

by chemical reactions. But the fabric remains porous to air.


4/10

Water Proofing Methods

1. Using Ammonium Acetate:In this method the cloth is run through the bath ofammonium acetate solution repeatedly withoutsqueezing and roll it into a batch, after which thecloth was left to drain.

2. Using Ammonium Soaps:This process is similar to ammonium acetateprocess but has two bath technique and the use ofsoap and alum simultaneously.

(Principle Chemical Reaction: Sodium soap isconverted to Aluminum soap to give the proofing

finish.)


5/10

3. Using Wax:- Good quality of paraffin wax is used along with

softening agent.

It is applied in many ways like friction, moltenspray, and aqueous emulsion.

- 4-6% wax is mixed in benzene and applied overroller revolving, the fabric passes through the

roller and gets dry and becomes shower-proof(temporary waterproofing).

Wax Emulsion composition:


6/10

4. Using Synthetic compounds:

Synthetic compounds of higher molecular weight havebeen used as water repellant materials. condensationproducts or polymerized compounds are also used forwater proofing.

5. Use of Silicones:

These products are stable to washing in water at 60Cwith solvents. They can be used to treat uniforms,raincoats and sportswear. These products are verypopular since they allow excellent waterproofingproperties, optimum solidity (that can also be enhancedif combined with resins) and a very pleasant and softhand(they are also used as softening agents.)They aresuitable to be applied on all types of fibers. The highwater-repellent effect and the soft hand are due to theorientation toward the outer surface of methyl groups.


7/10

6. High-Density Fabrics

In open-weave fabrics, water vapors transmitmainly through inter yarn spaces andtransfer through individual fibers, and fiberbundles are relatively unimportant. Thus,

fabrics of similar open construction, weight,and thickness are expected to show similartransmission rates, irrespective of the type

of yarn or fibers used.


8/10

Finishing Tests

Spray Test:Measures resistance of fabric to surface wetting undermild water impact.

Highest rating is100; 70 is the lowest acceptable ratingrequired for many repellent fabrics.

Rain Test:

Penetration of water through the fabric is tested by placinga blotter of known weight behind the fabric sample,spraying with water for a specified time, and re-weighing

the blotter. The intensity of the water impact can beadjusted by using a higher column of water.

The highest test level generally used for apparel is 3 feetfor 5 minutes.

Passing the test depends heavily on fabric

construction(tightness).


9/10

Bundesmann Rain/Shower Test:

Subjects fabric to an artificial rain shower,

rates the specimens visually for surfacewetting, measures the water absorbed by the

specimen, and measures the amount of water

that penetrates through the specimen.This is a severe test of water repellency.

Hydrostatic Pressure Test:

Fabrics are subjected to increasing water(hydrostatic) pressure until 3 points of

leakage appear.


10/10

THANK YOU

water proof and water repellant finishes

Documents