A third foam question

[G DANE]

Using the polyureathane foam, I noticed the foam creates a "skin" when hardened out. <br /><br />Will pouring foam several times, in smaller batches, so that the foam portions are seperated from "skin", make saturation slower ??<br /><br />The can says the foam hardens and expands by the humidity in air. Will foaming on a warm day with high humidity make it expand more ? How about wetting surfaces as I read another place. Will foam still bond ?

 

[JasonJ]

Re: A third foam question

The saturation is going to be governed by the integrity of the individual cells, I don't know that the skin is a factor. I suppose if it is a factor then one can assume that multiple skins can slow saturation. I didn't put quite as much thought into mine, I just poured in small batches through holes so I didn't worry about wetting or any of that.I will say that the more humid, the less it will expand. Ideally a nice warm day with low humidity will get you max expansion. Good luck...

 

[paulmw]

Re: A third foam question

All itchy from cutting fibreglass/carving out foam in my sailing dinghy - in which I descovered something relevant to your question.<br /><br />The foam in my boat was poured in at least 3 layers (and colors!!). The skin you referred to did form a kind of barrier; however, this actually caused a problem as the water which got in spread ~3ft+ from the crack in two ways: (1) down the foam/fibreglass interface (where the foam meets the hull), and (2) following the "joints" between the layers of foam. Where the layers of foam met, this boundary proved porous - more porous than solid foam. So the foam itself was dry, but the foam/foam layer acted as a wick, spreading the water away from the original penetration area.<br /><br />Make sense?<br /><br />I hope that this helps!