Protection using 2 part paints

[Tim]

This was posted on TSBB by a knowledgeable sailor and cabinet maker. Please all using 2 part Isocyanate paints heed this warning.

It has what industrial safety experts call 'poor warning properties,' meaning by the time it causes burning of the eyes and mucus membranes, you've probably inhaled enuf to wreck your internal organs & certainly enuf to cause potentially fatal allergic reactions. Very few organic vapor cartridges will remove iso. Only 3M's best OV filter with N95 prefilter (or similar for other companies) does a reasonable job of cutting exposure. Strict exposure limits and filter-change schedules must be followed, ideally with isocyanate monitors pinned to each worker.

From 3M library (link to PDF below it):

"The odour threshold for isocyanates, ie the level at which an individual can smell an isocyanate, is typically higher than the allowed exposure limits. In other words, if a painter smells the sweet, fruity, pungent odour of an isocyanate, they are probably already overexposed. That is why the recommended respiratory protection for employees spraying isocyanates is a supplied air respirator and not an air purifying respirator (i.e filter cartridge style). The issue with use of air purifying respirators is that they will reach a point at which the filter becomes saturated and will no longer capture the isocyanate or other solvents. When that filter breakthrough happens, an overexposure can occur, potentially causing an irreversible sensitization.

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&ved=0CE8QFjAA&url=http%3A%2F%2Fmultimedia.3m.com%2Fmws%2Fmediawebserver%3F6666660Zjcf6lVs6EVs66Sld7COrrrrQ-&ei=Tn0zUejNNsKGyAHL_YBY&usg=AFQjCNHrMnqVHz3Au2NZGst138LQCKSsNQ&sig2=zdVm-YmcztNEoYcMFlGe0g

Sensitization is the most immediately deadly hazard. Iso's other pathways may take years to kill you. But repeated exposure to it can lead to a radical histamine reaction, anaphylaxis, and suffocation. So disregard people who say "I've breathed the stuff a hundred times, hasn't killed me yet." Because the hundred-and-first time, you just might turn purple and croak.

Believe it, 3M wants to sell you overpriced filter cartridges. If they strongly urge you to forgo these and use supplied air instead, you can be sure they are unconvinced their vapor masks offer protection. Rolling and tipping 2-part PU without a hookah is reasonably safe if done outdoors. I'd never do it in an enclosed space, not even with a good OV respirator. Be safe, pls. This paint is not like other paints. It's not.

[Capt. Tony]

Fair warning, indeed.  I used Isocyanate paints when we were building a coral rearing system in the mid 90s.  It is nasty stuff.  It turns out using good old epoxy was much less expensive, easier, quicker and far more durable than the toxic stew in a can.  We could get by without adding pigment and had no real need for color.  You can still read about people using, and recomending, Isocyanide paint on wood aquarium installs.  :(