[Sparkle]

Ok don't laugh. I used 3m spray undercoater on my little Perodua car in Malaysia. It goes on very thick, dries fast, stays flexible and sticks like mad.

Why not spray the inside of cabinets with it? Seems it could help with slowing down reflections, and make vibration less likely. It's also fun to spray.

The difference on my car was insane after two coats. Those little stones that fly up very much quieter. (No stock held in 3m)

[FullRangeMan]

The inside colour will shape the sound response, car sound competition guys use mate black inside to decrease treble and resonances in subwoofers enclodures.

[mresseguie]

My first thought was "What are the health risks?"

Answer:
https://www.google.com/search?q=3m+spray+undercoating+warnings&sca_esv=c3663fb3fa70fe34&sxsrf=AE3TifPFR1KPS7Ovae2sCaANSEasp_ecDQ%3A1761653145388&ei=mbEAafC5F5mdkPIPiJu62AY&ved=0ahUKEwiw6sqv7caQAxWZDkQIHYiNDmsQ4dUDCBE&uact=5&oq=3m+spray+undercoating+warnings&gs_lp=Egxnd3Mtd2l6LXNlcnAiHjNtIHNwcmF5IHVuZGVyY29hdGluZyB3YXJuaW5nczIFECEYoAEyBRAhGKABMgUQIRigATIFECEYoAEyBRAhGKABSI5pUNcLWNlncAF4AZABAJgBYqAB1wiqAQIxNLgBA8gBAPgBAZgCD6ACuQnCAgoQABiwAxjWBBhHwgIEECMYJ8ICBxAAGIAEGA3CAgYQABgWGB7CAggQABgIGA0YHsICCxAAGIAEGIYDGIoFwgIFEAAY7wXCAgUQABiABMICCBAAGKIEGIkFwgIFECEYqwLCAgUQIRifBZgDAIgGAZAGCJIHBDEzLjKgB6dYsgcEMTIuMrgHswnCBwYwLjUuMTDIBzg&sclient=gws-wiz-serp

[nlitworld]

You totally can use rubberized undercoat inside the cabinet, but probably no additional benefit if you're also using something like the No-Rez panels. If you aren't using No-Rez, them yeah it could be good. I actually like the Evercoat version better but 3M is the big name.

And yes, there's always health risks with good automotive products, but nitrile gloves and a proper cartridge respirator keeps you safe.

[AllanS]

…and the risks being limited after curing.

[Peter J]

Seems to me we're comparing apples to oranges. Applying a sound deadening compound on sheet metal is not going to have the same effect as spraying same on (presumably) wood or wood composites.
The resonant nature of those materials is so different that any conclusion drawn about one would be, at best, minorly comparable to the other.   

[planet10]

Why not spray the inside of cabinets with it?

You are adding mass without stiffness. That lowers any potential panle resonances and lowers their Q, both making any potential resonance more likely to be initiated and more likely to be heard.

Now if you can lower the potential reonances below the boxea passband it will not e heard. Potentially useful in a mod cabinet, not so much for a woofer.

dave

[Sparkle]

Alright... potential to cause more resonance. that would explain why nobody else is doing it!