question regarding isocyanates during cure time

borna428

Promoted Users
Hi all,
I just applied urethane paint with brush that had isocyanate in its activator.
During the time I was brushing the paint, I was wearing full cover plastic cloth, 3M appropriate mask, and goggle. After I finished, I placed the part in the garage. Now When I entering the garage I can smell the paint. I want to know while the paint is getting dry / cure, does the ISO keep getting released into the air which could be dangerous? Basically I should not enter the garage even with the door open without a mask before the paint is completely cured?

Thanks
 
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I'm not in the paint industry, but use isocyanates in my work. Ive found that if you can smell them, they're in the air. When you're actively spraying, there's a whole lot of them. When it's curing there's a chemical reaction going on and they're no where near as much there. If you have sensitivities to them, they can still cause allergic reactions. I've seen blisters on someone's eyeball, rashes, etc. I'm working with the raw isocyanates in greater concentrations than you'll get in a quart of paint, so keep that in kind. If your not sensitive to it, it's not too bad. Small amounts accumulate over time, and with enough exposure you can become sensitized. But that's usually with a whole lot of exposure, or you're just already kind of allergic to it. These are cancer causing chemicals, so do what you feel is best for your long term health. Airing out the room is best, but if you're doing smaller parts and you give it some time to cure , air or out and it's probably not too bad. The isocyanates in higher concentrates will burn your eyes. All the other chemicals that make up paint smell too, so the majority of what you're smelling likely isn't much of the isos if it's cured for a while.
 
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The danger time for Iso's is when you are spraying. After clear is applied and fumes exhausted there is no appreciable danger of Iso's. Remember this to that Iso's harmful effects come from a cumulative buildup of them over time. Meaning day after day, month after month, year after year. Not downplaying their danger but very occasional painting using a charcoal filtered respirator is not nearly as dangerous as constant exposure.
 
The danger time for Iso's is when you are spraying. After clear is applied and fumes exhausted there is no appreciable danger of Iso's. Remember this to that Iso's harmful effects come from a cumulative buildup of them over time. Meaning day after day, month after month, year after year. Not downplaying their danger but very occasional painting using a charcoal filtered respirator is not nearly as dangerous as constant exposure.
So using a brush instead of spraying and doing it out door will greatly reduce its danger?
Also once you are done, does the ISO is keep emitting (like radiation :)) from the painted object for x number of days while it is curing?
 
I've read some say the isocyanates are odorless (incorrect), however they are characterized by a sweet aromatic odor Here is a excerpt from 3M:

The major hazard with spraying polyurethane paints is breathing the mist or aerosol droplets of the paint spray and absorbing the isocyanate and other components into your lungs. The odour threshold for isocyanates, i.e. 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 Page 3 of 3 Isocyanates overexposure can occur, potentially causing an irreversible sensitization. Use of a supplied air system removes this filter change factor - it does not rely on the painter changing his gas/vapour filters at appropriate intervals. Note: if isocyanate-containing paint is applied by brush, roller or dipping, in a well ventilated area, there is generally no more hazard than with ordinary paints. These application methods usually do not produce the higher concentrations of isocyanate vapour associated with spraying. After curing, polyurethane paints contain no free isocyanates and are not hazardous under normal use.

full article

 
Thanks all, I am not really worried much when I was applying the paint. As I said, I was wearing the correct filter and was in out door in open air, and was brushing it on. My main concern is now that the part is in garage and if it will takes about 7 days for the paint to be fully cured, is that means the ISO is still releasing into the air and unsafe to enter the garage without mask until that 7 days windows? Right now I can smell some very light paint oder in the garage, but nothing trouble but don't know if I can work there without mask or still not safe?
 
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