Life of 3M filters

I use a 3M filter designed for organic solvents when spraying but am a little uncertain just how long these things last once opened and how to tell when they need replacing?

Unfortunately it seems the 3M information is geared towards professional sprayers and suggests changing at the end of an 8 hour shift. Well that's fine and dandy but I'm sure as heck no pro spray painter and am not about to throw the things out each time I shoot 100 ml of enamel or poly!

Can anyone enlighten me on this?

Pete

If it's being used for just normal spraypaint and solvents, if you can smell the solvent through the mask, it's time to use a new canister. Keep the canister and mask in an airtight box (a large lunchbox or something) in between uses so the canister is not trying to absorb everything in the atmosphere.

If it's being used for isocyanate 2-pack paints...1) Don't. or 2) Change after a single use (by the time you can smell the nasties in iso, you are already over the exposure limit...so you can't tell how long you have been breathing it in)

Thanks very much. No 2 pack at this stage. I've heard enough about the evil stuff in that to put me off 2 pack and simple respirators. I've toyed with the idea of taking my Triton respirator helmet and using it as a basis for a fresh air system by building a "turbine" (actually they seem to be nothing more than a fan with filters attached) and plumbing it in from the next (clean) room. But it would still be a lot of work to get it all set up. I have a powder coating system on its way and I'm hoping that will take care of 90% of the jobs I would otherwise use 2K for. 2 upcoming jobs aren't however metal, so we'll see. Other than fresh air systems, are there any 3M filters that can handle isocyanates?

Anyway, back to the present. I've been keeping the mask in the draw string plastic bag it comes in, which is in itself kept in a larger plastic box with things like paint filters, bog knives, gun stand, etc etc in it. Not completely airtight but sounds like that will pretty much keep the airflow out and the carbon filters from absorbing too much. I must say they're mighty effective and it's sometimes a shock when I slip it off just how much the area stinks. A good mate used to work in the crash industry, most he wore was a cheap paper mask when sanding bog. Guy now has consistent cough and I can't help but think it is caused by not taking enough care in the past. That's the trouble with some of this stuff, you think you've got away with it, only to have the problems surface years later.

Pete

EDIT: On further research, hopefully I have answered my own question and you could confirm my understanding? It seems 3M doesn't produce any APPROVED cartridges suitable for iso use. However the problem isn't so much with the filtering through the carbon, it's indicating when the isos have broken through. So a good organic filter will be effective for iso use BUT you can't tell when it becomes ineffective. So for the occasional use they would be fine and the work around is simple to throw the filters out each time you spray iso containing paint. Does than sound right? Expensive, yes. But cheaper than building (never mind buying) a fresh air system, despite what I've read about people using old vacuum cleaners as blowers, not a bad idea!

The 'throw out after one use' is a last resort idea...you could actually do a 'use for iso once, then relegate to normal spray use only'.

You also need gloves, hooded suit and all that to keep spray mist off exposed skin.