What's most remarkable is that the environmentally-friendly foam—which is made from wood that's finely ground until it becomes a slimy goop that can be frothed—will actually harden all by itself after it's been sprayed onto a surface. Natural materials in the wood itself assist in that process so no additional chemicals are needed.
But the wood foam can be produced in sheets as well, like the large panels of expandable polystyrene you can find at home building stores. That process does require additional chemicals to help the foam rise and set, but the final product is still more sustainable and environmentally-friendly than petrochemical alternatives. Not to mention, it adds a whole other layer of authenticity (and warmth) to that log cabin you've always dreamed of. More here.