Just be carefull with the fiberglass. I would never consider it in the interior. Nasty stuff.

Recycled-cloth-style sheets would be my choice.

The Festool vacs are expensive, but one of my better investments just the same.

With my old Shop Vac brand vacuum, I refused to even turn it on without first putting on hearing protection.

I'd be very curious to see temperature reading of the motors as you have covered up the cooling features of the vac motors.

"With my old Shop Vac brand vacuum, I refused to even turn it on without first putting on hearing protection."

I am the same with my old Craftsman vac which was made by Emerson. It is over 30 years old but won't die. I checked the brushes last year and they still have plenty of life in them. It has gobs of suction but is noisy as all get out. Can't stand to use it without earmuffs for more than 30 seconds.

But I'll drag it out when I have something too nasty for the CT-36. That Craftsman is like a Billy Goat, it will eat just about anything and ask for more. Fortunately I still have 1 HEPA and 3 dry filters for it and they are all reusable so I should have enough to last me.

After two years of usage, the fibreglass insulation has proven a good means of reducing noise with no effect on the shop vacs or motors. If I have another shop vac to insulate, I may give the Rockwool a try. I'm open to all kinds of shop fixes.

Raining on my parade? Not at all; you're simply offering a warning on the risks of using the fibreglass insulation without care.

I determined that the material was safe to use as long as it stayed undisturbed:

https://dph.illinois.gov/topics-services/environmental-health-protection/toxicology/hazardous-substances/fiberglass.html

From what I gather (being a physical chemist by trade):

Asbestos >>> (fiber)Glass >> mineral wool (aka ROCKwool) >>> cotton/plastics/etc.

The problem with the first two is that the body cannot decompose the fibres.

The huge problem with Asbestos (as compared to glass) is that while glass fibers are actually liquid, so they break across (making them shorter and thus less damaging) the asbestos fibres are solid and brittle, they break "along the grain" into smaller but still fibres.
This eventually results into a bunch of so small fibres that stay "floating" in the air even over a several days/weeks period. Unlike glass fibres which will settle on the gound in a couple hours.

With rock wool, the minerals it is made from are mostly acid-solvable and the lung fluid will decompose them over time. So even if they scar the tissue, it is a one-off effect that will heal eventually. Unlike with glass and, especially, asbestos.

Now, again, being a chemist, I have a huge peeve with the "studies" equating the fiberglass with mineral wools. The problem is that the studies actually test NOT for the fibres decomposition but the fibres *binder* decomposition. And since the same binder is mostly used, they get "same" results. Now guess who funds these studies ... fiberglass producers. And who pays a study gets to define the question being asked ... formulate the question smartly, and you can mis-inform the regulatory bodies with ease ..


Either way, both fiberglass and rockwool are fine when not disturbed. So above is more for posterity than relating to your use case.

I mentioned it because the Festool vacs use sound dampening in the air path ... using foam which is safe. So I have (incorrectly) presumed you possibly did something similar .. or that someone reading your post may interpret it that way.