what's it called? waterproof foam

[ChattingLil]

Hi
I've got really nice cockpit cushions that are made of some sort of rubbery foam that is waterproof and floats.
I want to make some more - but I have no idea what it's called and google is not really helping me.
Anyone know?
thanks

 

[prv]

Referring to the foam as "closed cell" might help - that's what you need for it to be waterproof rather than soaking it up like a sponge.

Pete

 

[ChattingLil]

thanks. got it now. Pricey!!

 

[sarabande]

Polyester foam. Not expensive.

 

[Angele]

Polyester foam. Not expensive.

Don't think so:

https://www.merryweather.com/polyester-polyurethane-foam-polyether-know-difference/

Two disadvantages against polyester are that it is:
•Hygroscopic, meaning it deteriorates in damp conditions.
•More expensive to produce than polyether.

I think it is usual to use Polyethylene foam in damp conditions - typically Low Density Polyethylene (LDPE).

 

[Quandary]

However, they have been immersing polystyrene foam blocks in water for decades and it refuses to sink, racing marks, core of pontoon floats, shuttering etc. Despite its reputation as cheap rubbish only suitable for filling bean bags or packaging it still floats on, high and dry. How long do you need your cushions to float?
(By the way the polystyrene is not suitable for cushions, I just use it as an example of marketing talk down)
Maybe the doubts are seeded by the folk who sell the pricey stuff?

 

[lw395]

For thin cushions, a couple of layers of 'camping mat' is a start.

 

[duncan99210]

When making cockpit cushions and the like, I use multiple layers of 2.5mm packing foam like this https://www.easyfoam.co.uk/foam-wrap-rolls.php. The link is for large quantities but you can pick up the same stuff in smaller quantities in B&Q as underlay for laminate flooring. I use about 7-8 sheets for a thin cushion and 13-15 for a more comfortable one. The foam is quite firm so the Admiral usually supplements it with a scatter cushion or two for serious cockpit lounging...

 

[Yosilas]

A lot of Polyethylene foam is water resistant, being closed cell, it often has a low density compared to latex or polyurethane foam.