concern about supplied air mask

Now 3-M makes a mask that they say is good for ISO's(have called and talked the company). It whould seem safer to me to used a cartrige that I know filters out ISO's than risking having a pump push ISO's to me! Even if I did pick trace amounts around the edges of the mask.Any thoughts?

• using APR for ISO's

That link is interesting but I think you should review what 3M actually recommends in writing. Check out the "respirator guide" on their website (I seem to be unable to link to it directly at this time and I can't even get back to the link you provided - ???). They do cover at least one of the isocyanates common in paint (HDI). It indicates that an organic vapor cartridge is only recommended if the actual concentration does not exceed 10 times the occupational exposure limit. It also presumes that the respirator has been properly fit tested. Furthermore, a particulate prefilter must be used and the change schedule is totally up in the air -- at least as far as most individuals are concerned. Individuals also have no practical way to measure and monitor concentration levels, which can be highly variable. Don't forget that most people who paint at home do not have professional downdraft spray booths where the ventilation system keeps much of the overspray and vapors out of the painter's breathing zone anyway. Like you, I do all my painting outside. I once painted a snowplow where the curvature of the plow focused and directed a huge amount of overspray directly into my face. So much so that I could not see the paint being applied at times. I have never had a problem over many years of using my supplied air outfit with 50 ft of hose. I locate the compressor (portable) around the side of the house, safely out of the way of any vapors being carried by local breezes.

It is also interesting to note that in their guide, 3M indicates that a full facepiece supplied air respirator has a protection factor that is 20 times greater than a full facepiece air purifying respirator. That's their own analysis. Considering the unknowns with an individual using an air purifying respirator (APR) for isocyanates at home, I think it's a no-brainer that supplied air is the only way to fly, despite any recommendation from 3M that is accompanied by fine print and hard-to-define qualifications. Words are cheap. It's what they put in writing that is more telling. I see no evidence on the 3M website that they actually label any specific cartridge as "recommended for isocyanates". l doubt they will, simply because there is much more to it than the cartridge itself. In any event, for individuals not covered by regulatory agencies or local laws, it is a personal choice that has to be made -- hopefully while considering available evidence. I think the available evidence is overwhelmingly against the APR whenever isocyanates are involved.

Rod

You could also mount your air intake shielded from the wind from any thing such as a low tech card board box or a specially made container complete with filter. My system already has two built in intake filters. If your painting outside you can get down wind and leave the pump in the shop and shut the door too. I'd prefer the fresh air system. Plus if they can make a cartridge that filters ISO's, they can make the same filter for a fresh air pump where it would be 50 to 100 ft away from your gun and more effective.

An iso protective mask would be a great thing for the one time painter who won't buy a fresh air system despite the warnings and tragedies that have occured. You still need skin and eye protection too but its logical some protection is better than none.

Basically recommending frequent filter changes has been recommended as long as i have tinkered with paint, back to laquers. If they can make an ISO filtering mask, they should make a filter that lasts as well. But there is no economic incentative for them to do so. A product that is made well and lasts doesn't sell replacement parts. Sad truth, that they don't teach or discuss. But we just accept as the standard. Safety requirements have made a lucrative business for these companies but it doesn't seem they are investing any of it in better products that last.