Reader Michelle just asked me today: “Is Insul Bright safe to make a face mask out of, like if I were to put it in the middle as a filter?” Great question!!! But, is Insul Bright Safe for a Face Mask? My short answer is: no.
And I have a couple of reasons why I think that.
Let me explain:
1) Rather than air filtering, Insul Bright is to give padding and structure to fabric objects or garments. So, to have a bit of padding in there for the mask to keep its shape may seem logical. Insul Bright is washable, so why not?
2) Face masks won’t work well if it becomes moist. Insul Bright is made from polyester fibre. Even though it is marked as ‘breathable’ material, polyester or other less breathable fabric will typically produce moisture with breathing.
My personal view (I’m not a doctor nor have a Phd in meds or anything like this): Instead of using Insul Brite for shaping, I would rather use a heavier, non-stretch fabric like denim, duck cloth, canvas, twill, or other tight woven fabric. Its thickness should help keep the shape. Then for your mask lining/filter pocket, you can use thinner non-stretch 100% cotton layer.

Meanwhile, keep your Insul Bright to make school lunch bags, patchwork teddybears, other wonderful creative applications, as discussed in this article here: Insul Bright.
3) Let’s not forget that Insul Bright is designed to create pot holders, not face masks. Fit for its intended purpose, I read that it also contains 6.25% metalized polyester. I am not sure about that either for face masks, which you will have over your mouth/nose all day. Face masks are to be washed, a lot!!!! I personally would not want to breath in tiny metal bits that might break off over time. I am not sure if it will, but I don’t need that extra worry. Do you? I’d like to hear from the manufacturer about it. But in the meanwhile, if you are going to wear your masks day in day out, I would not put in Insul Bright. (I might be wrong re this factor — don’t hold it against me)
4) Insul Bright is to insulate. And it will be summer soon. Which means your mask will be really hot to wear. You’ll breath hot air into the mask. You’ll sweat. Read: moisture everywhere. i.e. it disqualifies the mask as protective. Don’t even mention the discomfort of wearing a hot mask. Which then may mean, that you/the kids will take the mask off, and yeah, that defeats the purpose of making one.
What To Do Instead?
First, realise the facts: the idea of a homemade mask offering protection for oneself against a virus is an illusion. Don’t take my word for it. Read up on it and you’ll find: The material most commonly used to make surgical masks is a non-woven material called polypropylene, either 20 or 25 grams per square meter (gsm) in density. This top quality standard material is designed to protect hospital staff from virus particles in the air.
In contrast, your home made face masks main purpose is for you to not touch your face with your hands all the time. And to keep germs inside, if you have a cold or a virus, and so as to not infect others.
In sum: there is NO COMPARISON between surgical masks and homemade ones.
So, if you are going to make a face mask, make a homemade mask out of the tightest natural fibre fabric you can find. Add a thinner nice and soft cotton lining from the inside and create a pocket for a professional filter mask to be put inside. And then put a surgical mask inside when wearing it.
Be Safe!