1/2″ Dry Fast Foam for Synthetic Over Quilt for Down bag?

Dry Fast foam is unique among the polyurethane foams in a couple ways.  The main way is that unlike other open celled PU based foams, it is actually fairly breathable and porous to both air and water. It was designed for outdoor use and to be able to get wet and dry fast.  They also make it very hydrophobic and anti-microbial for the above purpose/use as well.

It might be an interesting insulation for winter–particularly as a synthetic over bag/quilt to help move moisture out of down. Unlike other insulations, natural or synthetic, no matter how wet it gets, it will not collapse–it will keep its lofted structure.

I’m thinking of buying some 1/2″ in a soft or medium firmness and lining it in some .7 Monolite for the bottom and some woven polypropylene fabric* in the top.  *This is hard to source. I will probably have to buy a couple Terramar 3XLT men’s baselayer shirts and cut out and sew the fabric together.

Another use for it might be as an insulating active front only vest. In this case, line it with some wicking polyester fabric on the inside and some 1 or 1.5 oz Monolite on the outside. No matter how wet it gets, it will keep its structure and loft.  I made a 2.5 oz/yd2 Apex front only insulated vest, and it worked fine, but I think this stuff would work even better.

The downside to using this kind of material is the bulk. Also a question of, how well will it hold up to compression cycles?  But, using 1/2″ version of it will minimize the former and not sleeping or sitting on it will minimize the latter. And I use a larger volume pack in the cold/winter anyways.

For the over quilt, I’ve also thought of some ways of increasing the insulation value at low’ish weight. One idea is to fluff up some polypropylene microfibers and put it in there.  Another is to thin some silicone and put fumed silica in it, and then bond the fumed silica+silicone to the foam (I’m not sure this would work, so I would probably test it on a small test piece first).

Fumed silica is like the poor man’s version of silica aerogel. It has a similar weight and very low conductivity, but at much less cost. This is why it is the preferred core material for vacuum insulation panels (VIP).  The silicone coating would be both for putting a hydrophobic coating on it and helping it to bind to the PU material.

But, in all reality, either of the above are probably unnecessary, since the foam is not really being used primarily for insulation, but more to move moisture from the down.  And fumed silica, even with a silicone coating and bonded to the PU (if it can be), would make for a more stiff and less compressible material and it would be somewhat brittle.