READ THIS: Respirators and 2-Part Paint

[sho305]

Here is the mask I use, was recommended at various times for urethanes: http://forums.screamandfly.com/forum...m&pagenumber=2

It has charcoal and P95 filter or you can get P100 prefilters for it as well. It fits me fine, and I have tested it with the test scents a few times when I was painting at work. You can get a full face version, but I don't due to paint spray. I use safety glasses and have not had a problem with spray in my face and have good ventilation. I leave if I am not spraying. Lately I only have done it a few times a year.

You guys are right, and $400-500 is a great deal for air supply. I find it very hard to believe 3M would lie in our legal climate, and there is their number anyone can call. Some people can be sensitized to it in a very short time of exposure, you never know. Most autobody workers never do however. Like I said, that is why I got out of it. I just believe with the proper use/fit/etc this mask works and is safe, and I would get exposed to it in other ways much sooner than breathing it. If you are working with it often, I feel the respirator offers too much room for error to be safe. I am very careful to follow corrrect proceedure for its use and use adequate exhaust while I spray.

OSHA says I can use this mask. For a short time they said no, but found that they do work and rescinded that decision. They found the isocyinates were only in the paint spray, or droplets, and the respirator captures them. They can not physicaly be smaller than a P95 will capture and still be a droplet of paint. Other things like certain dusts can be smaller and require a P100.

It is no different than joe blow trying to wire in a switch without turning off the power, and he might get zapped. If you don't use it right you can get exposed and have no business doing it. I'm not saying the mask is as good as supplied air, but for $20 if used right it will do the job for you. If you're the type that does not follow directions, get supplied air. If you are afraid of it or just want to play it safe, or a mask does not fit then get supplied air. I would get one if I did it more often, as it is my autobody stuff takes up too much room here for how much I use it...but I never know when I will be needing it.

Yes Techno, the hoods are much nicer to use. Nicer for glasses, beards (a must), and you can see better with no obstruction in the case that you can use an open face. If you have a dryer on one, it will A/C the air for you too.

[gaineso]

I know back in the late 80s I was working in a steel fab shop. We were doing bridge girders for the state of Alabama. They got a 3 coat epoxy/urethane paint system, not sure exactly what. Our shop was over 1/4 mile long and had open ventilation. With painting at one end and me upwind 1/4 mile away, I still had to wear a respirator or I would get light headed. And several others were severely affected too. The paint crew used full "Moon suits" with supplied air and they would be dizzy by the end of the shift.

Some of that stuff is worse than chemical weapons.

[sho305]

That was likely the very nasty solvents some epoxies have in them. You were huffing Usually does not hurt you depending on the levels, but still not good. Isocyinates have a cumulative effect so they build up, then your body freaks out on them in essence and you have an attack where you can't breathe. It is in foam also, so you can also react to new carpet and couches for example.

The problem is urethanes are the best thing going and an amazing product. Until something better gets here you just have to be wary of it, and you don't feel any effect like from solvents. I am pretty sure it has no smell aside from the paint it is in.

[Techno]

sho305

Does it say on the cartridge what chemicals it filters? Should specify Isocyanate if it takes them out.

[MattGreen]

Some states follow the federal OSHA standards, while others have their own OSHA plans, and the 2 are not always the same, so it's difficult to generalize.

Here's a possible basis for OSHA making that statement. Bear in mind I haven't read that decision, please direct me to it if it was a written statement. Different respirators have different "assigned protection factors", which is a number that basically quantifies how effective the respirator is a reducing the quantity of contaminants in the breathing air. A half-mask (the typical cartridge style), has a factor of 10, and can be used in an environment with contaminants at 10x the OSHA permissible exposure limit (PEL). A full-face cartridge system is 50, the battery-operated shield/hood systems vary somehwat, but are typically in the 100-250 range, and positive pressure full-face supplied air is 1000. All these numbers vary slightly with the jurisdiction, but these are typical numbers. OSHA, NIOSH, a company-exployed industrial hygienist, or another qualified person performs air sampling to determine what contaminants are in the air, and how much of each. They then select the level of respiratory protection needed. Respirators are actually the last resort when all other control measures are inadequate. The exposure limits for isocyantes are so low that it's extremely unlikely a half-mask could achieve the exposure limit in a typical setting. The basis for this may be in sampling done in a paint shop with a really good spray booth and HVLP guns, using a paint with a faily low isocyanate content (it varies with the product). In this case, I could theoretically see it MIGHT be possible that a half-mask could be adequate, but it still is considered bad professional practice to suggest it.

Incidentally, for all the auto painters that I've scared: a properly designed spray booth, full-body chemical coveralls (and gloves), and a full-face supplied air respirator gives you excellent protection from isocyanates. Wear the gear, maintain the booth properly, and you're good to go.

Incidentally,
If you read the text that accompanies all those 3M masks, they say "paint spray", not 2-part urethane spray. If you go to the 3M UK site, the 7500 series half mask specifically states it is for NON-isocyanate use. Bear in mind there is a hell of a lot of paint spraying that occurs with one-part or other non-polyurethane paints. The furniture finishing industry is a major user of 1/2 masks of that type, and many of their finishes are simpler nitrocellulose laquer or traditional solvent-based varnish or shellac (alcohol) finishes. Half masks are OK for many of these applications.

I'm not going to get into the details of isocyante toxicology, I think I've written enough, you have to trust me that you should protect yourself from these substances.

Matt Green

[sho305]

I specificaly suggested you *not* use a repirator in "professional practice." I certainly never suggested that use; I suggested a backyard guy who is going to spray once/few times a year and not use anything special should use a respirator such as this that will be effective.

I researched it twice and that is what I came up with. If I was lied to by 3M, others, OSHA, and the largest local auto paint supply place, then I was. If you don't like it, then you use air supply when you spray. This was a big deal when urethanes first came on the scene, and everyone went around and around until they found it was not that big a deal; only for a very few people who get sensitized easily. Like I said, isocyinates is in the paint like metallic is...so are you breathing metallic when you use a good respirator? It is not a solvent that releases from the paint, it stays in there, and is in the spray not fumes. Certainly the possibility of exposure is greater with only a repirator by its design, but if it takes out the spray then it takes out everything in it.

Auto paint is full of nasty stuff, you should protect yourself from all of it carefully and use what you think is needed to do that. I have been told by many this will work if properly used in a bodyshop. With an air test they normally last 99 hours they said. I use one for one or two paint jobs a year and I'm not doing more just for that tiny usage. I even use it for spray can paint, I'm not stupid and would not do this if not instructed by many who's jobs and reputations ride in it.

I left the bodyshop after spraying for 5 years because I would be wetsanding a car and the guy next to me would up and spray something on his car. I didn't want to wear a mask all day.

What you are seeing with the 'not recommended' is in some areas they still rule you can not use anything but supplied air for urethanes. It was that way here for a time, but not now. In areas with that ruling they advertise you don't use them for it. I know a fair amount about it having worked with it professionaly and since I have a family member who is sensitized. I said repeatedly you can't go wrong with supplied air, I just concluded from what I can find the exposure is very low if any to use this for a one-off application. Of course, if you find proof this mask does not work, then let me know. The only proof I have found was from misuse/poor fit/etc., problems I don't have. The only thing I am careful about is getting it in my eyes, so I wear protestive glasses and am very careful about airflow and spray direction/etc.

[MattGreen]

I've said my piece, I think we've flogged this horse to death. Bear in mind you won't know you are more prone to sensitization until it occurs, and then it's like trying to unring a bell - can't be done.

Ultimately it's the individual's choice what level of protection they choose to wear. I'm an industrial hygienist that designs protection strategies for industrial chemical exposures on a daily basis (including respirators), and I do not reccomend this practice, but suit yourself.

What really matters is that there's enough time after painting for boating and beer !

Matt Green

[sho305]

I know there are many people on this site who will do a job once in a great while and not buy air supply for it. I don't want them to go use some crap dust mask when they can get a nice one for $20. I would not spray urethane on a daily basis without supplied air no way, no how. Even if the mask works 100%, there is room for error in fit and use that will show with prolonged use. Everytime I say I'm not going to use it anymore some project comes up...and I do another job. Been a year now though. If I shave in the morning for example, I sometimes can't get a tight fit in the evening and have to shave again.

The guy I know had isocyinate chemicals dumped on him under a tank of it. He since has had a diminished lung capacity, and has a nasty reaction to it like an asthma attack where he can't breath. He runs to get a shot of wiskey or an inhailer. He is retired now and it seems to not bother him much now, but it could shorten his life. For the first 20 years he had inhailers on him all the time, but now I don't see them around. Smoke and dust still bothers him some, but he makes lots of it anyway. The guy is nonstop and is welding, grinding, or wrenching on something all the time. Of course he smoked a few packs a day before that happened also. On top of all that, they could not get the stuff off of him, so they used something now illegal like MEK(?) to wipe it off... Imagine taking a bath in something like that. The problem is the reduced lung capacity will be hard on his heart, and likely his end. I'm glad it seems to have reduced effects after all this time.

[1BadAction]

so the final word on isos is... a bare MINIMUM of protection is supplied air/full facemask and protective clothing only. right from NIOSH http://www.cdc.gov/niosh/asthma.html

edit- upon further inspection, certain correctly fitting full face respirators can be worn. info is in the link.

[MattGreen]

I don't want to get into this again, but I strongly feel that "home-spraying" of isocyanates using air-purifying respirators is a bad idea. It doesn't help that most of the shows on TV show the "expert painters" using half-mask cartridge respirators when spraying polyurethanes.

If you really want to get into the details of WHY, I will explain it - there are a number of reasons.

Think of it as not wearing a helmet when riding your streetbike - it might never be an issue, or you might REALLY regret it. Your choice.

Matt

P.S. I can't find any reference to air-purifying respirators being acceptable in that document - they refer to 2 types of air-supplying respirators.

[175checkmate]

Great post. Thanks for taking the time to post.

[Jack]

Please correct if I’m wrong. I believe isocynates are odorless and continue to leach out of the paint as it cures. So we finish painting close up the shop and leave. Next day we open up the shop and admire our work not realizing the shop is full of odorless poison gasses. The shop must continue to be ventilated.