Why the gusset in briefs is made of a different material

Short answer: The gusset is sewn in a material that can move moisture, whatever the rest of the brief is made of. It is a consideration for the skin and not for the look.

Moisture away from the skin

Dry skin is less prone to irritation. That is why the gusset is almost always cotton or viscose, even in lace briefs where the rest is synthetic. See bamboo briefs.

The whole brief does not have to be

If the gusset is right, the rest matters less for comfort. That is why you can wear a synthetic brief without trouble, as long as the gusset is a natural material.

When the whole brief is bamboo viscose

If the whole brief is one material, there is no transition between two fabrics, and that is one place fewer where friction can arise. See bamboo underwear for women.

Washing affects it

Fabric softener lays a film on precisely the layer that is meant to move moisture. It is the one thing that can put the function out of action. See washing and care.

Frequently asked questions

Why is the gusset cotton?

Because it has to move moisture away from the skin. Dry skin is less prone to irritation.

Does the whole brief have to be natural material?

No. The gusset is the part that matters most for comfort.

Can fabric softener affect the gusset?

Yes. The film settles on precisely the layer meant to move moisture.