Hi Chuck:

Your observations are correct....if the stuff in the hardware store can was properly manufactured, there should be no isocyanates in the can.....once the isocyanate is hydroxylated and polymerized at the proper temperature and pressure, in the presence of proper catalysts, all the isocyanate molecules are converted to a long chain of urethane molecules, hence Polyurethane on the label....no one gets scared that way.......once the stuff polymerizes, it is very stable in either the liquid, foam, hardened paint or plastic form at room temperature or slightly above, but if it starts to get very hot or burn, it can break down and give off free iso's......we have all heard of the toxic fumes given off when full scale planes crash and burn and the polyurethane seats cushions light off........one of the toxins is free isocyanate....mixed with smoke, bronchospastic suffocation is almost certain as in ValueJet 592.....

During 30 years of medical practice, I only saw one case of severe bronchspastic reaction to iso's......it was a young guy, about 20 years old shooting PPG in his garage, with only a small exhaut fan under his nearly-closed garage door.....and he did have a history of childhood asthma.....yet there are literally hundreds of guys locally who have shot iso's and epoxies, even lacquers with just a paper or poorly fitted charcoal mask for years.....mild reactions do occur regularly with guys who elect not to wear proper protection, but life-threatening reactions are rare...

In no way am I suggesting not to use proper safety equiptment......I own an AXIS/CITATION twin turbine HVLP unit and Hazmat suit...kinda pricey BUT DON'T FORGET....if you live in the north country, spray a little anti-fog on the clear face plate, and the hood makes the best snow blowing headpiece around......keeps the frostbite off my nose and cheeks when the wind swirls at 25 kts right in my face, no matter which way I turn, when blowing 12 inches of fresh powder at 10 below zero......


Tom