How long does a water repellent last?

pu1. If you use water repellent, you can think of the expiration date for about three years, but you can think of it as working again every three years

2017-11-22

OK

pu2. If you want water repellent and long lasting, it's tricky, but I prefer latex or paraffin wax

2017-11-22

OK

pu4. I don't know where you're working, but in cities, meteors are prohibited

2017-11-22

OK