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mbell 01-07-2021 02:06 PM

Decent charcoal respirator?
I use a forced-air system for the nasty stuff, but a charcoal respirator is nice for the occasional rattle-can and non-isocyanate spraying. My old mask worked perfectly but the cartridges are no longer available. I've tried two sizes of a 3M respirator and they don't consistently do the job. Recommendations? 01-07-2021 03:59 PM

solution to problem
Having built custom homes for 41 years and now retired I can tell you about old tools that still have value.
Oh ya, that includes a few respirators that are no longer supported by manufacturers.
We use what we can find, But usually just tape them on with either duct or electrical tape. Seals where it's needed and you usually only use them once. All you are asking is to filter the air.
On that matter if you have a few squirts and short duration. bag it and you may find it works just fine for the next few squirts.
Oh ya if I have a small job of only half an hour I will get the respirator that has one side taped off and only use one cartridge. Saves money and still works for me. Them cartridges seem to go up in price every time I want to buy some more.
I have a Hobby air system for longer jobs.
Enjoy the fresh air. Art

mbauer 01-24-2021 12:57 AM

Curious, what brand you're having issues finding the OV filters for?

Honeywell North? They are starting to ship again.


mbell 01-24-2021 10:43 AM

I think the old one was a Honeywell, and that's what I'm going to try next.

1001001 01-24-2021 11:22 AM

I work for a company that makes activated carbon (not charcoal--the difference in terms is important!) that goes in many different kinds of gas masks and respirators. We don't make the respirators ourselves, but manufacture the main ingredients that get the job done.

No one respirator is going to have a good fit for every user--people's face shapes and bone structures are just too different. If the 3M can't be made to fit you, there are others you can try, as you mention--Honeywell, MSA, and others. Unfortunately you kind of have to try several if you have a face shape that is not "standard."

You probably already know, but I'll point out here that if you have facial hair (even light stubble), a respirator that might normally seal well for you when you are clean shaven will no longer provide adequate protection. And a marginal seal on smooth skin will become useless with facial hair. When I go to prime parts, I make sure I have at least run the beard trimmer over the seal area--I have a respirator that seals pretty well and I can get away with a little stubble, but others cannot.

Between uses, you can store the respirator or just the cartridges in a sealed zip-lock bag--this will protect the activated carbon from adsorbing any other volatiles that may be in the air where you store it. Over time, if the activated carbon is not stored sealed, the adsorption pore sites will be used up and the overall effectiveness reduced or exhausted.

I have a set of 3M VOC cartridges that have lasted me at least 4 priming sessions of about an hour each--your mileage will vary depending on how well ventilated your paint space is and how well you keep them sealed between uses. I wear a forced air hood over my respirator, so I probably get more life out of mine than if I were simply relying on the carbon to remove VOCs in the direct painting environment.

Once you have a well-fitting facepiece, as soon as you can detect any trace of VOC aroma when you breathe in, it is time to change the cartridges--the bed depth in these cartridges is rather thin and at the earliest signs of breakthrough you are being exposed to the hazard.

I would not recommend sealing one cartridge off out of two--that will only cause the single cartridge to become exhausted more quickly, and it becomes harder to breathe. Far better to seal the whole respirator in a bag when done with it.

Prior to bagging the respirator after use, use isopropyl alcohol to clean the facepiece, otherwise bacteria from your face and mold may tend to grow on the rubber. Also, skin oils can have a detrimental effect on the rubber, so cleaning it before storage is important.

1001001 01-24-2021 11:27 AM

Oh, also--if you have some cartridges for one type of respirator facepiece and they don't fit another that fits you better, there are adaptors you can buy. If you have a 3D printer, there are models available on places like Thingiverse for adapters between most brands of facepieces and cartridges.

It also helps to use a snap on filter cover for VOC cartridges, if available, so that the cartridge doesn't become clogged with paint particles before the carbon is exhausted. I know that 3M and MSA make these snap-on style overfilters, and probably other brands do as well. They are worth it if it helps extend the life of a relatively expensive VOC cartridge.

LCampbell 01-25-2021 09:30 AM

An idea to add on the above 'put the cartridges in a zip lock bag' remark...

I know chemical levels will determine how quick the active ingredient is used up, but whenever I was putting my cartridges back in the zip lock bag, I'll put a 'tick' mark on the bag with a marker for each hour use..... 25 ticks later, then I would no longer count them usable for hazardous vapor absorption.

I'd still hold onto them for particulate filtering, such as fiberglass sanding work, but not for hazardous fumes.


SkyJunkie 01-25-2021 10:25 AM

Just a note for readers who may not be aware: there is not a respirator made that will filter Isocyanates from your breathing air. Use a forced air supply. If you need convincing, google Isocyanate sds (safety data sheet) and read it. PPE listed is a "positive pressure air supplied respirator"

SkyJunkie 01-25-2021 11:04 AM

Just a note for readers who may not be aware: there is not a respirator made that will filter Isocyanates from your breathing air. Use a forced air supply. If you need convincing, google Isocyanate sds (safety data sheet) and read it. PPE listed is a "positive pressure air supplied respirator"

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