Nikwax, either wash-in or spray on is DWR which means (Durable Water
Repellant) in other words it's not intended to restore waterproof-ness.
Waterproof is the job of the Gor-Tex (or other) mid-layer of the fabric.
The DWR keeps the outer fabric from becoming too soggy and heavy. If you
are having trouble with waterproof-ness, maybe the garment is too old
and the Gore-Tex is failing. An earstwhile son-in-law had a pair of very
old Gore-Tex pants in which the mid-layer membrane simply disintegrated
into small shard and powder. Not waterproof whatever.
And this is a test to see if my re-vamped system can poast to rsam.
VT