DIY Rockwool panels (Wrap with plastic?)

[Holmz]

I am making from frames and have sourced some rockwool.
And working on sourcing a print to cover the front of the panel.

I have heard some talk about wrapping the rockwool in the thin painters drop cloths, which would seem like they should transmit tehe sound pretty good as their low stiffness and mass sort of precludes them from really keeping the wave from coupling through.

What is the general schools thought?
Wrap them in this thin plastic to keep the fibres all contained or not?
I am not even sure whether the plastic would last very long, as it should just turn to dust, or maybe that is more of a UV light induced breakdown?

Looking for some guidance here.

It is for a panel directly behind the sofa which is against the wall wityh the ears 16” (400mm) from the wall. So trying to diminish that Initial slap echo - which is not hugely evident to begin with.
It would probably be worse if the sofa was not pull out into the room about 10” to a foot… but that is about as far as the Feng Shui manager will tolerate it from a decor perspective.

 

[ryanosaur]

I wouldn't want the rockwool, and if I did, I wouldn't wrap it in plastic.

IIRC, it's about air particles... soundwaves are air... If you wrap it, air cannot penetrate.

As long as you aren't playing around with the panels... beating on them, constantly moving them, the rockwool should be reasonably inert.
When you are working with it, you should absolutely wear a respirator and work in a well ventilated environment, especially if you are cutting it.

If you want something much more friendly, the recycled Denim insulation is far safer and much more environmentally friendly. I know it's not the same as rockwool, but in those other ways it is better.

 

[Holmz]

I wouldn't want the rockwool, and if I did, I wouldn't wrap it in plastic.

IIRC, it's about air particles... soundwaves are air... If you wrap it, air cannot penetrate.

As long as you aren't playing around with the panels... beating on them, constantly moving them, the rockwool should be reasonably inert.
When you are working with it, you should absolutely wear a respirator and work in a well ventilated environment, especially if you are cutting it.

If you want something much more friendly, the recycled Denim insulation is far safer and much more environmentally friendly. I know it's not the same as rockwool, but in those other ways it is better.

Thanks Ryan.

I can see a panel out in the velocity region of a room would be exactly like you say. In a region where hair tricks and pant legs flapping indicates velocity.

This one will be on a wall it is sort becoming mostly in the pressure domain region with the boundary condition of the wall <4” away from the front. So there is not a great amount of velocity as the frequency drops towards 0.

Those particles of air imping upon the thin plastic and then on the otherside the particles of air (or molecules) jump and pulsate exactly like they were on the incoming side… except for what is lost to heat on the plastic.
It‘s pretty much like inside of a Russian tank spallation of metal from the kinetic energy and momentum transfer of a Ukrainian shell hitting the outside.

I’ll keep that in mind for the cloud absorbers as they will be a foot off of the ceiling.


Denim is not readily available here, but I have the respirator, and a Hazmat looking painting disposable (Michelson man) suit.
Maybe I should just wrap them in amn extra felt layer before the the thin acoustic print goes over the top?
(Assuming I am being somewhat paranoid about the fibres.)

 

[ryanosaur]

@Holmz
I am definitely not an acoustics expert. Seems like these type of panels still work on the premise of converting sound energy to heat, as a standard absorber would.

I like your idea of wrapping it in a fabric rather than a plastic film. As long as it is acoustically transparent you will achieve the goal.

I absolutely share the same sentiments about Rockwool. …Completely get where you are coming from.
I’ve had people tell me I’m over-reacting in my dislike for the material, but I’d rather be on the safe side, myself. I know you don’t want to breathe it. I think a simple long sleeve shirt and gloves is enough to protect your skin; no need for the Tyvek suit!

Good luck with the project!

 

[Holmz]

Thanks @ryanosaur - I’ll go by the local sewing place (equivalent of Jo-Anns) and get some thicker quilting fabric… Maybe wool, cotton polyester or a cotton/poly blend.

I just try as find one I can blow through but is not too loose in the weave.

 

[highfigh]

Painter's cloths are made from a material called 'muslin'- you should be able to buy it in whatever quantity you need at the fabric store. I used it for my panels, which are made with 1" thick Owens Corning panels and I haven't noticed any fibers coming through, but I don't move or handle them, so there's little risk of this happening. The NRC for the Rock Wool will determine the area and thickness you need, so it will be slightly different from the amount I needed but I didn't treat the back wall, just the front wall, the 1st reflection area on the left wall and the FR, FL and RL corners (the RR corner is a doorway).

It's not a matter of being able to blow through it, look through it- if you can see through the cloth, the sound will pass through it. There's a lot more energy behind your breath than in the sound hitting it.

 

[highfigh]

@Holmz
I am definitely not an acoustics expert. Seems like these type of panels still work on the premise of converting sound energy to heat, as a standard absorber would.

I like your idea of wrapping it in a fabric rather than a plastic film. As long as it is acoustically transparent you will achieve the goal.

I absolutely share the same sentiments about Rockwool. …Completely get where you are coming from.
I’ve had people tell me I’m over-reacting in my dislike for the material, but I’d rather be on the safe side, myself. I know you don’t want to breathe it. I think a simple long sleeve shirt and gloves is enough to protect your skin; no need for the Tyvek suit!

Good luck with the project!

A decent face mask should work, but some people are more sensitive to the fibers' irritation, so I guess the Tyvek suit is up to the one making the panels.

At least it's not resin-infused- I'm still trying to remove one resin-coated fiber that's in my right thumb and it's annoying.