For several years, 80% of our sales of outdoor cushion or mattress projects have been made of nautical foam to benefit from this water resistance. All our professional customers take this quality, especially for sun lounger cushions that are heavily exposed to water.
The only drawback we can find to this solution is that the cushions are not reversible. The soft grid bottom (white or black) will not allow the cushion to be turned over to use the other side.
If you want ease of use, not to run as soon as it starts to rain, then 100% outdoor cushions are made for you.