7 Difference Between Water-proof & Water-Repellent Finish
Though both of the terms seem quite the same. But there is technical differences between waterproof and water-repellent finish. How great it would be if any garment can keep you dry from any angry weather! To choose the right product, you need to know the basics it.
So, if you want to know about the difference between waterproof & water-repellent finish, then simply I would answer from the International Standards definition.
So, according to them, If the entry pressure of water is above 8.00 mm hydrostatic water column on any textile substrate, then you can term them as water-proof but any textile material below this range is water-repellent.
Before jumping into the differences between water-proof & water-repellent fabric, let’s know what they exactly mean.
What Water-proof describes?
The waterproof finish is given with any hydrophobic substance of rubber, PU or PVC that forms continuous layers on the surface of the fabric. To make it waterproof, any fabric needs to resist all the passage of water into it. Interstices, seams, any type of opening in the material aren’t allowed.
The fabric labeled as water-proof should be impervious to water. With the help of seam sealing tape, all the seams connecting the outside to the inner side of the garment should be blocked so that no water can penetrate. These fabrics are not comfortable.
Nowadays, membrane based products provide better water-proof performance. Though polyester and poly-urethane membrane provide better results they lose their efficiency with aging, UV radiation and so on. GORE-TEX fabrics provide better water-proof performance.
If a product is given waterproof finishing that doesn’t mean it will be water-proof forever. If the rain exposure of the water-proof material lasts for too long hours, it may permit the way of water into it.
What does Water repellent mean?
If the entry of water pressure is lower than 8 mm then the fabric is called water-repellent. Water repellent fabric is also given a coating of hydrophobic substance but no continuous film is formed.
Water-repellent fabric is produced on the idea of repelling or rolling on a liquid globule from the surface of the fabric. The surface contact angle is the one that is taken into consideration to make this fabric.
Water globule that makes angle below 90 degrees can penetrate the substrate whereas the contact angle above 90 degrees repels the water globule.
It prevents the water molecule to spread over the surface. So, the water drop is rolled on the fabric. This type of fabric can prohibit water passage up to a certain time.
But with the high hydrostatic pressure, water gets into it. This is because the interstices are not sealed here. These fabrics are comfortable.
To escape a watery shower without any discomfort, water-repellent fabrics are best.
Difference Between Water-proof & Water-repellent Finish
Completely impervious to water or vapor phase
When the hydrostatic pressure is enough high, it can permit the passage of water
A continuous layer of hydrophobic substance is deposited on its surface. Rubber, PU, PVC etc materials are used for it
Hydrophobic substance is deposited on the surface but no presence of a continuous layer
No open pores
It has open pores in the structure
It is not breathable
It is breathable, air passes through open pores
The interstices of the yarns are also sealed
Interstices are not sealed
No penetration of water through any high hydrostatic pressure
Resist water globule to spread on the surface enabling it to roll on.
Example: Can be used in apparel
The Last Word
If you want to relieve from light rain then water-repellent fabric is best. But for the heavy raining season, you definitely need any product that is waterproof.
Salma Hasin the author of this site completed her BSc. in Textile Engineering (Wet Processing Engineering). She wants to share her knowledge to help students in their studies and businessman & entrepreneurs in their businesses in making wise decisions fast.