To be clear, “water-repellency / oil-repellency” does not mean “waterproof / oilproof”.
Water-repellency is defined as a surface’s ability to repel liquid … up to a certain point.
To explain how water-repellency works, it is first necessary to explain what a liquid is.
Besides their seemingly great diversity, all liquid are made up of either water or oil. Water and oil are known as solvents. Besides water or oil, the “rest” of the components in a liquid are called solutes.
A liquid is a solvent in which a solute has been dissolved or diluted.
This is why, to repel a liquid, we just need to be able to repel its solvent.
To make INDUO® fabric repel water and oil, its cotton fibres were made to be hydrophobic and lipophobic.
So how come certain liquids can penetrate into fabric?
What does “up to a certain point” mean?
When subjected to a fairly high level of pressure, liquid can penetrate the fabric. Knowing this is essential in caring for your garment.
Your washing machine will reach this level of pressure so it can pass water and detergent into a fabric. However for this reason, it is not recommended to rub a spot.