As raf48 says,if its nylon then never,if its cotton/polycotton it depends on how much you use it.
When we had our Comanche Montana TT it was all lovely Tencate canvas.We had it 7 years,used it 3 times a year and it was never reproofed.Never let a drop of water in.
------------- Sue & Phil
--------------------- I Love My AeroBed
No need to re-proof it for several years to come but if you see Fabsil at silly prices then buy some, it can also be used on hiking boots and coats, so you're bound to get your moneys worth.
------------- Steve
Look into my eyes, not around my eyes but into my eyes
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