SouNdguy,This looks like the stuff you are talking about: 
I think that MSDS you got from Valspar is the right one for that hardener, at least according to Valspar. As you say, the numbers match up well. What's really bothersome to me is that the iso compound you mentioned (isophorone diisocyanate) shows up on the can label but not in the MSDS. There may be different rules for product labelling and MSDS preparation - I don't know. I am also troubled by the reference to isocyanates in the text of the MSDS for no obvious reason. The use of the words "NIOSH Approved" has always been unclear to me as to exactly what has been approved by that body. A for instance is the Hobby Air fresh air respirators. There are actually two versions, one is claimed by Axis (the manufacturer) as "NIOSH Approved" and one is not. The one that is presumably NIOSH Approved is referred to as the Pro Air model. As far as I know, NIOSH has never "approved" any type of fresh air source such as a turbine or compressor used by Axis or any other company. They may have approved the facepiece parts and the connecting hose, but I doubt very much that NIOSH has approved the entire system of the Pro Air for isocyanates, despite the manufacturer's claim. They (NIOSH) have indicated in the past that they "encourage" the use of such systems as being an improvement but have not approved them because they have no control over where the turbine/compressor is located. They have only indicated that the air supplied for breathing must comply with Grade D of the federal spec for breathing air. That makes sense to me. It is very misleading to suggest to anyone, that since they have a "NIOSH Approved" system, they are safe. That's not necessarily true. They certainly wouldn't be safe if the user placed the turbine in the same room he was spraying in. It's all quite confusing really. The "threshold limit value" concentration of 0.005 ppm for most (if not all) of the isocyanate compounds is the concentration that is presumably safe for most healthy individuals to breathe on a time weighted average over 8 or 10 hours every day. I believe there is also a "ceiling" of 0.02 ppm that must not be exceeded, even for a short time. That's for most, not all, individuals. That's my understanding of it. If it is shown that the concentration in the air doesn't exceed 0.005 ppm of the hazardous component, then in theory and regulation, a respirator is not necessary. Of course the DIY in a home shop environment, even outdoors, has no practical means to measure or determine exposure values, which can be highly variable. He has absolutely no way of knowing if he has exceeded any established "safe" values. NIOSH is conservative in their recommendations. They recommend that supplied air be used if isocyanates are involved at all, even if the concentration is below that threshold limit value. In other words, at all times isocyanates are used, period. That is clear in the two NIOSH links that I have posted previously on this subject. Even 3M, which does recommend their organic vapor cartridge for some isos, does so only on the conditions that the iso exposure concentration is known and is less than 10x the threshold limit value (0.05 ppm). They clearly state that if the concentration is not known, then supplied air is recommended. All this and $5 will get you a cup of coffe at Starbucks, I think. Anyway, if anyone wishes to play the numbers game when the numbers are not known, they can certainly can. It's there own decision. Hopefully they will at least be informed of the variables involved, weigh them carefully, and decide on a level of risk that they feel is right for them. I always go with supplied air if there is even a hint of isos involved, but that's just me. Rod
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