READ THIS: Respirators and 2-Part Paint

[MattGreen]

This post is in response to the thread below on respirator use. I felt so strongly about it, that I made a whole new thread.

Sorry guys, I never read this particular forum, or I would have responded sooner. I have bad news for you as well - 2-part polyurethane paints, which contain one or several diisocyanate components, should only be sprayed using a supplied-air respirator. Supplied air means a hose delivers purified air to the respirator (typically full-face or loose-fitting full-face). Because the respirator is under positive pressure, rather than negative pressure with a regular "1/2 mask" (i.e the ones with the cartridges that you "suck" through), it is considerably less prone to leaking ambient air into the respirator. Full-face supplied-air systems are expensive, as are the filters necessary to get compressed air from an industrial-type compressor anywhere near breathable quality.

Why should you care or continue to read this lengthy post ? Isocyanates are especially serious substances because they are sensitizers; this means that they sensitize the body's immune system to future exposures to that substance. Here's how it works: you expose yourself to isocyanates a few times (or even once), and become sensitized. You may not even know this happens. Then, some time in the future when you are exposed again, even to a VERY small amount, you will have a horrible asthma-type respiratory attack, and often skin problems as well. All isocyanates have this effect, and some are acutely toxic as well (acute refers to a small, short-term exposure causing immediate harmful or fatal effects).

Two-part epoxy paints do not contain isocyanates, but do contain epichlorohydrin, a respiratory tract irritant, and the hardeners contain some mixture of of amines, also sensitizers. People with asthma, smokers, or others with compromised immune systems are particularly vulnerable to the effects of these substances. Epoxy paints also contain a variety of solvents.

In all honesty guys, 2 part paints should only be sprayed in downdraft booths by painters in full chemical-resistant clothing and supplied-air respirators. There's a reason why this equipment is standard-issue in professional body shops. Spray booths are partly used because obviously they improve the finish quality, but they also are there to protect the workers. A shop not using one is putting a bulls-eye on their head for an EXPENSIVE OSHA visit.

My suggestion is to do the prep work yourself, which we all know is 80% of a good piant job anyway, and then get a body shop to shoot it for you. You CAN adequately protect yourself from solvent vapours (i.e styrene from polyester resins/fillers, acetone from cleaning tools), and sanding dusts with a properly-fitting half-mask respirator, assuming your work in well-ventilated conditions (i.e keep the garage doors open, use a fan to create a cross-breeze, etc.). For solvent vapours, you need an "organic-vapour cartridge", which will be black. For dusts, get a P-100 cartridge, also known as HEPA cartrige, which will be a purepleish colour. You can also get cartridges that combine these, so you don't need to switch back and forth.

As for care and use, those that mentioned respirators must be stored in sealed bags are quite correct. The organic vapour cartridges cannot distinguish between solvent vapour and any other organic vapour, such as farts or cooking odours (I'm not joking). Thus, their lifespan will be prematurely shortened by not keeping them bagged. Respirators should be washed in a mild soap after every use, then allow them to dry and bag them. Failing to do this could cause bacteria or fungi to grow inside, which you then inhale. You probably don't want the equivalent of athlete's foot in your lungs do you ? If they are cleaned properly they can be shared between workers.

The most important thing to remember about wearing any kind of respirator is that it can't protect you if it doesn't fit properly. You need to be clean-shaven in the area it will fit on, and need to fit-check it after putting it on. The 2 straps on the head band should be spread as far apart as possible on the top and back of your head, and the neck band should be snug, but not uncomfortable. The 4 tensioning straps should be tightened alternately, 2 at a time (i.e. top 2, bottom 2, top 2, bottom 2). This helps the mask seat properly on your face. Once it feels OK, do a fit-check: cover the cartrige openings with your palms, and inhale moderately. If the mask is fitting properly, it should collapse inwards and you should not hear or feel any leakage around the seal. If you do, the mask needs to be readjusted. This is called a "negative-pressure field check". In addition, you can also block off the exhalation port at the bottom of the mask, and exhale moderately; the mask should inflate without popping the seals. This is called a "positive pressure field check"; the negative is the more important of the two.

I could write a whole bunch more, but this post is pretty huge already. One thing for everybody to think about: the latency period on many long-term diseases is 20 or 30 years. This means that the health damage doesn't show until decades after the exposure. For many substances we use, the long-term health effects are not well known. It is in your best interest to protect yourself from chemicals that we can reasonably expect to cause long-term health effects, even if, at this present moment, we don't know for sure. Remember asbestos and lead ? They were not originally thought to be toxic either.

Feel free to post questions and I'll do my best to anyswer them, but I'm only on here twice a week now so my response may be delayed.

Matt Green,
industrial hygienist

[delawarerick]

Matt good stuff! I can appreciate and fully understand what you are saying. I have industrial lung diesese and the long term can be old real quick. What I did 20 years ago is hitting me hard now. This imformation should be text. Rick

[Murph]

Excellent, excellent post.

The most important post I have read on this board. One that even one should take great concern in understanding. Having worked for a boat manufacture and made my own boats it is not news to me and I have always taken care when using these types of products. But I see many on this board that work from their garage and don’t take precautions when using such products. Even products that aren’t as dangerous as the ones used for boats and cars should understand them before they use them. Always follow manufacture recommendations and if you don’t know find out from the manufacture.

I had a fellow worker once who thought it would be a much faster if he sprayed his latex paint on the walls in his basement. No great fumes from latex and it washes with water, so his thoughts were how could it hurt. He did not use a proper mask and that was a BIG MISTAKE as he had breathing problems for months and I am sure it will bit him again when he gets older. What he didn’t understand was what happens when to the good old safe latex when sprayed and the fact that part per billion becomes so fine he had no idea he was doing damage. This is the same that type of occurrence that can happen when you get too high a concentration of PPB of sawdust in the air – instant explosion.

Again this is an excellent post and all those that want to use these products should take Matt up on his offer to pick his brain. I am no expert, just learned ahead of time how to use the products properly.

Another one that comes to mind (not so much for breathing) but I wonder if most backyarders know what happens if you put too much hardener in your resin? At some point when the percentage of Hardener is too great to the percentage of resin you will not be around to make the same mistake again. BOOOM. How many store their hardener next to their resin. If something leaks and the two mix its BOOOM again. Many fibreglass shops have gone up in smoke when their resin sprayers (chopper gun) were not properly looked after and they leak when no one is around and that’s the end of that. There’s enough fibreglass on the floors and walls that mix with the hardener and that’s that.

Better to be too careful then to not enjoy the boating season.

Chris

[gaineso]

Very good article. Thanks.

[Techno]

What he said.

The nice thing about a supplied air system with a hood is there is almost no care, fit don't matter and is great for other stuff like sanding glass.
With a tyvek suit and all space suited up the itchies are non existant, and you don't get it in your hair

[Alan Power]

Thanks for taking the time to write such a clear and informative piece.

Alan...

[MattGreen]

You guys are all more than welcome, those kinds of reponses are the reason why I chose this profession in the first place. In time, I'd be quite willing to write a more in-depth special article for the site, summarizing the health effects of the various products we use and the best ways to protect yourself.

By the way, what Techno said about supplied-air respirators with loose-fitting hoods is quite correct. These typically have a face shield attached to a helmet or headband, and a Tyvek-like hood that loosely fits under your chin. These are very comfortable to wear, never fog up, are cool, completely protect your eyes, and are less likely to irritate your skin. They are great for grinding glass and woodworking. Another type of respirator that uses the same type of facepiece, but does not require a compressor or airline, is a Powered Air-Purifiying Respirator (PAPR). This has a battery pack/fan/filter unit that you usually wear on your belt. The unit filters the air through a HEPA or other filter, and supplies it through a hose to the facepiece. Also great for grinding glass. These are available for <$1000, and would be a good investment for anybody doing a lot of glass work. We had an airline-type loose fitting mask at the glass shop I used to work at and it was very popular.

Matt Green

[Bruster]

Great Information!!

Inhalation is only one way this stuff gets to you. It is just as bad on your skin or eyes. A full Tyvec suit and gloves are also recomended.

But the best advice is take the finish work to your body shop with the proper paint and bake booth. You get great work and the price is reasonable. I say reasonable for 2 reasons:

1st, The materials are expensive. You only pay for what you use at the shop.

2nd The work is done quickly and the results are first class.

[1BadAction]

a hood that attaches to the shop airline via a filter would be considered supplied air, right?

usually we use it to sandblast...

[MattGreen]

Yes, technically that is supplied air. But, I'm somewhat concerned about the air you're using. There's considerably more than basic filtration needed to take "shop air" and convert it into breathing air. I'm pretty sure there are systems available to do it, but I'm not familiar with them. I'm accustomed to breathable-quality compressors or manifolded air cylinders.

I'm glad to hear you are wearing a hood for sandblasting. Non-contained sandblasting ALWAYS requires supplied air "hoods", which are somewhat different than supplied air respirators. The hoods include a tough headcovering that extends down the chest and back, require higher positive-pressure flow rates, and have tougher/replaceable facepieces to account for the abrasion damage. Only a real sandblast hood should be used for non-contained sandblasting (you didn't mention if you were only doing it in a cabinet). If we're talking about a cabinet, a dust respirator (or even a supplied-air respirator) is still required; I've yet to see a cabinet that didn't leak.

The reason for the increased protection is because the silica sand often used for sandblasting is a tremendous respiratory hazard - silica causes silicosis, a horrible lung disease, which has claimed a lot of sandblasters.

Matt

[1BadAction]

thats what it is. a helmet like deal with a clear face and leather covering down to mid-torso. it is made to breathe out of while sandblasting. it has built in hearing protection so you dont go deaf. the filters for it are pretty expensive, and the sensor in the hood beeps like hell when it needs chainging. also, the air coming out of it is like 65 degrees, even when its 100 outside.

I am talking about uncontained. we use a 150HP diesel powered sandblaster to do what we need to do. some of our pumps have 60" diameter impellers and are over 40' long. all of them need to be blasted and painted before final assembly...

[sho305]

If the air is cool it likely has a cooler on the air supply? They are common in shops for painting air supply, thay are a filter and A/C unit to take all the moisture out of the air.

All this is great info and the best way to do it! But, most people can't or will not spend $1000+ for equipment to spray a car or boat once in a while. It was law here you had to use this stuff for two part urethanes, but they did away with it when they figured out the proper repirator will infact take the stuff out of the air. If you don't use the right safety equipment in the right ways, then yes you will get screwed up. If you do it every day you should be using air supplied equipment if not just because it is easier and more mistake-proof.

3M recommended to me the P95 filter for two part urethanes. I have used it with west epoxy and dupont urethane they recommended it for, and never once smelled it or was affected. I am very careful and only do it on occation. I have researched it an found no proof that if used properly you can not safely spray urethane with a respirator. Some idiot that does not use the right stuff will always cry about it, and I am sure the lawyers will then outlaw it some day so the rest of us can't do it. Yes, I used to work in a bodyshop and sprayed every week minimum. I also know someone sensitized to isocyinates, but not from auto paints. They are not a solvent and once the place was fully exausted of spray this person could walk around in there with no problem, or if they used the respirator when they were. They would get a nasty attack if isocyinates were present.
The other problem you run into, is most now use catylized primers on things. So, you may as well put on full protective gear before you even work on anything as you will be exposed. It is much easier to work with a respirator.

My point is certainly not to cut down anything here, just that the backyarder can properly protect themselves without supplied air equipment if they have to, or if they choose to. Glad you pointed out the air supply problem; you can't just hook a hood up to a standard air compressor that is full of oil, you need a special compressor or a special filtering unit to breath that air. All of these chemicals was infact the reason I got out of the autobody biz. Even with all the equipment, if you are in that building where it is used you are exposed to stuff.

[MattGreen]

sho,
I new sooner or later somebody would respond exactly as you have. You're quite right, lots of people spray 2-part urethane paints at home using a half-mask respirator, and don't suffer noticeable ill effects. I'll be honest with you, they are "rolling the dice". They are taking a risk, and might find out later they are sensitized, it's not a predictable type of syndrome. I'd compare it directly to screwing a bunch of bar chicks without wearing a "jimmy": good at the time, but you might regret it later.

Consider this:
IF the half mask fits perfectly (nobody here is trained or has the $10,000 equipment to test the fit), AND the cartridges are new and changed out quickly enough (smell alone is not a totally reliable indicator for end-of-life), this idea MIGHT be OK for OCCASIONAL use. You could increase your protection somewhat by wearing a full-face respirator, they protect better than a half-mask and use the same cartridges. I'm not trying to be a dink, just give everybody the best information I can. I strongly reccomend against this idea.

Incidentally, a P95 cartridge is a dist/mist HEPA cartridge, and is not suitable for organic vapours (i.e painting). When spraying, you need to collect the vapours (solvents and isocyanates, amongst other things), as well as the aerosol (the tiny droplets of liquid in the air). That's why you use disposable dust prefilters that clip over the organic cartridges when spraying finishes. The P95 will do a great job of removing aerosols, but overall will actually be detrimental. Here's why: without a charcoal cartridge to adsorb the vapours from the collected aerosol, you get to inhale it all ! The P95 will actually kind of concentrate it right in your breathing zone ! Did you mean a combination P95 and organic vapour cartridge ? That would be fairly big, probably with a purple top and black (threaded) sections. The P95 or P100 alone is great for sanding fully cured fiberglass or body filler.

There's an awful lot involved in designing protective measures for chemical exposures, and to be honest, the guys selling paint aren't qualified to do it.

Matt Green

[BarryStrawn]

Since I am no longer young and immortal, I bought a HobbyAir II with 80 foot of hose and a Bullard hood a few years ago. It was a bit over $400 which seemed reasonable compared to the price of paint. Or lungs

[Techno]

What he said. Mines a neoterik and with 100' of indestructable hose and nylon hood was only $500. Cost a mask and replacement cartridges over time- factor in they don't protect you and it may come out even. Not sure how many filters it would take though.

I am fit tested for all the crap, the alphabet soup of abbreviations. And by far the hood is much more comfy than any kind of mask. Figure in I wear glasses and its an easier choice.

If you can't afford the protection either take your chances or don't do it. Same deal with the boat safety gear.
Painting your whatever is partially for the fun of it and to save money. Both are canceled out if it makes you sick.

I believe OSHA has stated what is permissable. This would be required in all states no matter what the local law was. I don't see how a state could make it more lax.


We just got 4 battery powered respirators with hoods because of the fit deal. Since there were some people who couldn't be fitted they bought those. These are for chemicals you can smell before their danger point.

sho305 your missing a basic point. With isocyanate your not protected with a negative air respirator. Negative air being your lungs sucking a vacuum inside the mask and any leak letting the poison past the filters. These leaks can be from a strangely shaped face, facial hair or even an old mask. Even movement which most people forget all about.
These aren't allowed in commercial outfits for a reason. You may be limiting your exposure but you have no way to determine what your exposure is.
Like I mentioned its like the boat safety. Either you have the gear or you don't. A PFD isn't a race jacket.