Ted the Kiwi said..
I have had some pretty robust discussions with a fella who runs one of the big SE producers of boards and he said it's a real challenge blowing the foam as the temp and humidity changes means you are continually adjusting the formula to produce a good blank. He also said that the actual process of blowing foam is very very dangerous. Trying to get his staff to wear appropriate safety gear is a major battle every day ! In terms of glassing be said the cheaper brands and expensive ones are pretty much all done exactly the same.