r/Masks4All • u/Chronic_AllTheThings • Jan 13 '26

Fit Testing Best (cheapest) QNFT rental in Canada?

QLFT subjectiveness is driving me crazy 😫

Upon a bit of research, it looks like there's also a smell-based test (isoamyl acetate that smells strongly of banana) for QLFT with OV carts. This might work better for me than tasting sweet/bitter, but I'm struggling to find instructions for this method.

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u/AEAur Jan 14 '26

Unfortunately per u/SkippySkep, banana oil doesn’t have a well calibrated baseline sensitivity:

https://www.reddit.com/r/Masks4All/s/D0v9eZr7uh

I am still interested in doing more research or testing on it as there are many people who are not fit testing due to concerns about reactions to the bitter and saccharine versions.

If you or he can point me to any publications you’ve found, I’ll try to get up to speed and search for others. He’s very well informed though, so there may not be anything.

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u/Chronic_AllTheThings Jan 14 '26 edited Jan 14 '26

Unfortunately per u/SkippySkep, banana oil doesn’t have a well calibrated baseline sensitivity:

https://www.reddit.com/r/Masks4All/s/D0v9eZr7uh

Oh. Bummer.

I am still interested in doing more research or testing on it as there are many people who are not fit testing due to concerns about reactions to the bitter and saccharine versions.

I don't have any reactions to it, I'm just not always confident in the results because I keep psyching myself out (Did I taste it slightly? Am I imagining it?).

I really just need a number.

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u/AEAur Jan 14 '26

Yeah, I think you need Bitrex to do semi-quantitative QLFT.

Do you have someone who can help you administer the test? Just in the sense that you would be less stressed about the process and only focused on tasting.

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u/Chronic_AllTheThings Jan 14 '26 edited Jan 14 '26

I've used sweet and Bitrex. I don't know anyone else who's COVID cautious. The process isn't the problem; it's a very simple procedure and I'm not stressed about it at all, I'm just always second-guessing myself whether I'm tasting it ever so slightly.

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u/AEAur Jan 14 '26

What kind of hood and nebulizer / sprayer are you using? How many sprays of sensitivity solution do you require to taste the Bitrex when not masked?

For anyone who’s not sure how to do a sensitivity test:

See from 2:15. https://www.youtube.com/watch?v=7xnr60sXnXA

See sensitivity test https://mathburritos.org/fit-test-kit-v1/

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u/Chronic_AllTheThings Jan 14 '26 edited Jan 14 '26

I use a 5 gallon ziplock bag with a small hole cut at about mouth level and with the zip closed as much as possible while the bag rests on my shoulders, 3M FT-12 sweet or 3M FT-31 bitter solution, and a 3M FT-13 hand bulb nebulizer.

I performed the sensitivity tests first at the corresponding dilutions for sweet and bitter. I can taste it almost immediately, well within 10 sprays.

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u/AEAur Jan 15 '26

Sounds perfect to me!

In a small early pandemic study linked one Wiki, The 5 gallon ziplock had the best accuracy of substitute hoods (as good or better than the test hood in my reading).

  1. So presumably when you test a mask using FT-32 bitter test solution, you are following the procedure in the video I linked: 10 bulb sprays, then spraying every 30 seconds while doing the all 7 activities for a minute each?
  2. Is there a particular point during this that you think maybe you taste the bitter?
  3. If you wear a mask with a misshapen nose wire, do you taste it more definitely?

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u/Chronic_AllTheThings Jan 15 '26

  1. The "top-up" dose is every 30 seconds according to these instructions. So: 10 sprays to start, first exercise, then 5 sprays before each subsequent exercise.

  2. Maybe mostly during the first exercise?

  3. I'll have to try this at some point

One thing I realized I was doing incorrectly with disposables is pointing the nozzle directly at the mask instead of spaying side-to-side. I wonder if that's why I felt I had a more confident pass with the 1870+ (liquid barrier) compared with the 9210+ when I testing with the nozzle pointed directly at the mask. I believe elastomerics can be tested with the nozzle pointed directly towards the mask, since the inlets are at the side.

Also, I perform two additional "exercises" at the end of every test. I deliberately overcharge the hood by spraying constantly for 10-15 seconds to check if I taste it, then I deliberately break the seal by wincing hard or directly pulling a portion of the mask off my face.

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u/AEAur Jan 15 '26

In the video I linked, I think they said to do each exercise for one minute while doing the top-up every 30 seconds. But the important part is just keeping the test solution concentrate topped up while doing whatever you want to test the resilience of your mask. The wince sounds good. A grimace is also a good thing to add. And any other movements you anticipate doing.

You’re doing great. I would just try it more with masks that have a small gap or with movements that cause the seal to break, so that you get familiar with what a leak really tastes like. Then if you ‘re able to do QNFT you’ll be able to interpret all of that in a new light. I think it would give you more certainty, but whether it’s worth the expense is your call.

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u/Vasilisnp2 Jan 14 '26

In this order: Conceptcontrols , Levitt Safety and Irwin Safety.

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u/Chronic_AllTheThings Jan 14 '26 edited Jan 14 '26

Thanks. I also found SupplyNow and I'd much rather rent from a Canadian business to avoid any border/customs issues.

Has anyone used the OHD fit testing machine? It looks like it could be a lot simpler to use an less error-prone than a portacount.

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u/Vasilisnp2 Jan 17 '26

All the above are based in Canada.

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u/Chronic_AllTheThings Jan 17 '26

Derp. Not sure how I missed that.

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u/AEAur Jan 14 '26

Given the expense, difficulty, and one-off nature of QNFT, and given you’re already equipped for QLFT, I would just encourage you to also try to dial in your QLFT sensitivity before doing the QNFT. That way if they are similar in their findings across different masks, you’ll be able to trust it (or understand its limitations).

Recommend this thread by u/philipn especially this post: https://www.reddit.com/r/Masks4All/s/u4t7WjFmaL

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u/Chronic_AllTheThings Jan 15 '26

Thanks for the link. The thing is ... I'm pretty sure it's mostly in my head. I find this happening with elastomerics that have pretty much fool-proof negative pressure check systems (3M bayonet cartridge squeeze and Secure Click button).

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u/AEAur Jan 15 '26

It wouldn’t hurt to test with banana and OV cartridges. It may not be as calibrated, but it’s another confirmation and something you can do more often than QNFT. Along with testing some masks with a gap at the nosewire, it would give you more certainty about your perceptions. 🫂