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DIY acoustic panels with rockwool and a fan

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Re: DIY acoustic panels with rockwool and a fan

Postby Nyiregyhazi » Mon Jun 15, 2020 4:15 pm

When I was having the biggest issues, it was around the time when I had been cutting the stuff. I didn't always bother wearing a mask, to be honest as I cut it out in the open air (with a knife rather than high speed tools). If this was indeed linked, having it in fabric alone would still probably involve much less exposure, even with a fan around. However, after seeing the evidence, I'd rather make the seemingly tiny losses in performance than risk having even a partial version of those possible effects.
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Re: DIY acoustic panels with rockwool and a fan

Postby Sam Spoons » Mon Jun 15, 2020 4:31 pm

The consensus in that thread is to not cover the rockwool in plastic*. The one answer I would give most credence to is this one by David Shevyn who is general manager of Gig Acoustics Europe so he probably knows a bit about the subject.

If they are Bass Traps then low frequencies will travel through plastic. Plastic will relfect the higher and medium frequencies but if you was to use very thin plastic or cling film it will not make too much diifference. The thicker the plastic the more highs and mids it will reflect.

Oh and rockwool will not be airborne wrapped in fabric. You could just wrap in two layers of fabric

* Fire safety being one very good reason not to, burning plastics are not nice at all.
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Re: DIY acoustic panels with rockwool and a fan

Postby Nyiregyhazi » Mon Jun 15, 2020 4:40 pm

Yes, but the only tested example suggests next to no difference.

I hear a lot of theory on this issue, but I'm yet to see any dissenters show of a testing situation in which it was shown to have severe negative effects. In issues this complex I don't put much trust in theory but only in empirical data- especially when plenty of experts say plastic would be fine. Also, if the plastic is beneath a material, I'm pretty sure the flammability of the external material will play the biggest role in fire safety.
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Re: DIY acoustic panels with rockwool and a fan

Postby Hugh Robjohns » Mon Jun 15, 2020 5:05 pm

It possibly shows very slightly less absorption across the board with the plastic wrapping, but nothing significant and all well within the tolerances of repeated room measurements.

I don't see an acoustic problem in wrapping with loose clingfilm (or the like)... but equally, I don't see a significant benefit either in terms of fibre spread given a tight weave acoustic fabric covering. It seems a lot of extra work for minimal benefit.

The greater risk, as pointed out in that thread, is the risk of toxic fumes from the plastic sheet in the event of a fire.
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Re: DIY acoustic panels with rockwool and a fan

Postby aerotekmusic » Mon Jun 15, 2020 5:28 pm

As of recently, and also considering any possible risks both when the panels are static and when handling them, I've been looking into using recycled cotton acoustic panels. It's way better for the environment and the NRC is comparable.

I hope this info works for you. Also, if anyone has any experience with this material, I'd love to hear you out :)
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Re: DIY acoustic panels with rockwool and a fan

Postby cyrano.mac » Mon Jun 15, 2020 6:47 pm

Cotton, wool and some other stuff is fine for absorption. It is, however a fire hasard. And not much better if fibers end up in your lungs.

I tend to use rockwool board in stead of blankets. So much easier to work with. Spreads far less fibers while you work with it.

Don't use glass-fiber. Period. It will remain itchy for some.

Don't worry about fibers once the stuff is placed. Wrapping in plastic ruins mid and high absorption. And it isn't needed for health. Even a fan won't dislodge many fibers after a while. Vacuum a lot the first few weeks. Like daily, before work. After that, it gives off about as many fibers as your clothes. Would you work naked to protect your lungs? :think:
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Re: DIY acoustic panels with rockwool and a fan

Postby Sam Spoons » Mon Jun 15, 2020 9:23 pm

I think I said earlier in the thread that, after two years of infrequent vacuuming I have seen no visible evidence of RW fibres in the dust. It may well be impossible to tell TBH but I have spent much more time in the studio that previously and my sinuses issues have not worsened.

All the evidence points to your wrapping the RW in clingfilm causing a very slight reduction in mid and high frequency absorption but it seems wrong to me and David Shevyn's post trumps the others IMHO.

The fire safety issue is probably the one that would worry me, the Cara fabric is fire retardant, the rockwool is also fire retardant, clingfilm is flammable and hiding it behind a layer of fabric is unlikely to make any difference to that fact. Fire resistant in the case of the fabric and RW means it is hard to make it burn not about protecting other materials in the panel from catching fire and the fumes from burning plastic are not nice.

Hopefully you or I or any of us are unlikely to have to find out first hand.
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Re: DIY acoustic panels with rockwool and a fan

Postby Nyiregyhazi » Tue Jun 16, 2020 3:07 am

How would you know if any dust particles are from rockwool or elsewhere? I don't think there's anything so distinctive about them that there would be a way to distinguish. I don't see any equivalency between cotton clothing fibres and rockwool. The stuff may not be cause for outright paranoia, but the official line on safety is that it's dangerous enough to warrant breathing protection. That's certainly not paralleled by similar recommendations for when putting on clothing. There's reason for caution, as the particles could be truly tiny and I don't see why the body would have evolved to be particularly good at breaking down solid stone fibres. Just because you don't drop down stone dead at first breath doesn't mean there is no need for any real concern at all.

In terms of fire hazards, my bed sheets are flammable too, as are the vast majority of ones around. I've also got no shortage of plastic around my house in general, which would also cause fumes. I wouldn't really put it down as being notably reckless to have some small amounts of plastic covering a substance that cannot catch light from the plastic.

There are a few things to weigh up, but I definitely prefer to err on the side of extra caution about the fibres. The context it's designed for is being stuffed deep inside walls. Even for that context they advise significant caution whilst working with it, so I don't think you can dismiss possibilities too casually, just because nobody has died.
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Re: DIY acoustic panels with rockwool and a fan

Postby zenguitar » Tue Jun 16, 2020 3:59 am

There are real risks and there are perceived risks. The problem with erring on the side of extra caution is that you run the real risk of increasing the real risk in a misplaced attempt to deduce the perceived risk.

The road to Hell really is paved with good intentions.

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Re: DIY acoustic panels with rockwool and a fan

Postby Sam Spoons » Tue Jun 16, 2020 11:12 am

I'm happy to go with the opinion of the General Manager of GIK Acoustics that rockwool traps don't represent a hazard when I construct a few extra panels for my room. Rockwool has been around for long enough that any significant hazard would have become evident in the construction industry by now.

If it makes you feel better to have taken the precaution of wrapping your panels in plastic then that's fine too. You need to feel safe in your own space.

Good points about the evidence of fibres, and the other plastic items that would create a hazard in the case of a fire.
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Re: DIY acoustic panels with rockwool and a fan

Postby Hugh Robjohns » Tue Jun 16, 2020 11:41 am

Nyiregyhazi wrote:... the official line on safety is that it's dangerous enough to warrant breathing protection.

Only when being handled and physically disturbed. That's not happening when the product is installed in a frame fixed to the wall.

So if you walk into your studio every morning and take a carpet beater to your acoustic panels you may create a dust problem... If you leave the things alone, and they are wrapped in a tight-weave fabric, considerable experience suggests they do not spontaneously generate dust or particles.

Of course, the wrapping fabric may well trap normal dust particles floating around in the room from skin shed and other natural processes which may give a false impression that the panels generate dust.

There's reason for caution, as the particles could be truly tiny and I don't see why the body would have evolved to be particularly good at breaking down solid stone fibres. Just because you don't drop down stone dead at first breath doesn't mean there is no need for any real concern at all.

Sure... but mineral wool has been used for many, many decades in professional and home studios and there isn't (AFAIK) even the faintest suspicion of evidence of lung-related problems to the users of finished installations. Handling and physically cutting the material is a different situation entirely.... so it's obviously appropriate to use and wear protection during the installation work. But I'm not aware of any credible evidence that working in a room fitted with mineral wool panels represents any tangible risks.

I wouldn't really put it down as being notably reckless to have some small amounts of plastic covering a substance that cannot catch light from the plastic.

It's not the things that can't catch fire that are the problem... it's the ones that do. And in a fire we all know that plastics typically generate toxic fumes, even if they only melt, rather than actually burn.

But you are quite right in that there are lots of other materials in a typical studio that are potentially inflammable, so it's about managing risks again. In a DIY project, wrapping panels in clingfilm maybe considered an acceptable risk.

In contrast, for a commercial panel manufacturer taking that approach may well be impossible because of the difficulty of achieving a suitable fire rating for the finished product.

There are a few things to weigh up, but I definitely prefer to err on the side of extra caution about the fibres.

Sure. That's your prerogative, and it appears (from, it must be said, very little empirical evidence) that wrapping mineral wool loosely in a clingfilm-type material has only a very small effect on overall absorption performance. So if wrapping your mineral wool panels makes you feel better about it, and you have the time and inclination, I'd say go for it.

However, it's not something I've done myself or felt the need to do, and I wouldn't (currently) advise anyone else to follow the same route based on my own experience and understanding.... but I wouldn't advise them not to either.
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Re: DIY acoustic panels with rockwool and a fan

Postby Nyiregyhazi » Tue Jun 16, 2020 12:53 pm

Hugh, where is the evidence that tight weave acts as an impenetrable barrier? I feel you're starting as if this were a given. I don't think it is. This thread is also about having a fan to agitate the air right by it. Just because it feels like something basically keeps it all in isn't the same as having evidence for that, especially not regarding the fan.

Regarding health, if something can be dangerous in extreme it can also be more insidiously dangerous in smaller quantity- in the way where you don't either drop down dead right away or necessarily even know anything of what is happening. This is how asbestos functioned. Check out all the many online articles comparing them, and raising serious questions as to whether rockwool is notably safer. I can rate the opinion of audio experts on audio but not on issues of health. Would you have asbestos around as long it was behind a layer of fabric. Admittedly, I wouldn't even have it behind added clingfilm, but the point still stands that something doesn't suddenly become zero risk because the product is widely used by many. I think the audio community is a lot less averse to rockwool than the general population due to its sheer value and familiarity, but the sense of familiarity doesn't completely remove concerns in the wide world.

In terms the level of risk in terms of performance, I'm applying Occam's razor unless I see empirical data of significant rather than minor effects. Popular as it is to theorise of clingfilm as a limiter. I haven't seen either strong theory or real world evidence of high percentage losses. Clingfilm isn't typically some incredible sound blocker or reflecter and while the theory is sound to say it has most of its effect on the upper end, I won't be convinced the effect of thin plastic is vast unless I see actual recorded data. Most likely its a matter of a small effect being concentrated at the high end, but continuing to be small. The only measurements I've seen taken supported this. People repeat the theory a lot, but it seems to me that this is chiefly based on people repeating what they heard already, rather than on actual tests. If I'm wrong, I never saw those tests, so where are they?
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Re: DIY acoustic panels with rockwool and a fan

Postby Nyiregyhazi » Tue Jun 16, 2020 1:08 pm

By way of comparison, I heard a thing before about how schools "specialise" in a subject. When a school sells itself this way, you assume they must be particular good in this area. However, it can also be that a really crappy school that specialises in drama, say, is one where they get terrible results all around the board. Neighbouring schools that don't specialise in drama may be getting vastly superior results in that same field. It was just that they were even better in other fields. The bad school just takes pride in the only place it can try to find it, purely on the basis of comparison to what it does even worse at.

To me, the most probable truth is that thin clingfilm is rubbish at blocking sound in general but that it "specialises" in high frequency- ie it does a less incompetent job than at blocking low frequency. If I'm wrong, only recorded data would convince me, as the example here shows just how misleading theory can be, without full context about specifics.
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Re: DIY acoustic panels with rockwool and a fan

Postby Hugh Robjohns » Tue Jun 16, 2020 1:27 pm

Nyiregyhazi wrote:Hugh, where is the evidence that tight weave acts as an impenetrable barrier?

If it was an impenetrable barrier it wouldn't work for its intended function, would it? What matters is that the pores are too small to let mineral fibres through... and that seems to be the case when using Camira Cara fabrics, and even more so using Camira Lucia which has a tighter weave.

This thread is also about having a fan to agitate the air right by it.

It was... ;)

I think we all understand where you're coming from. You must do what you think is right for your situation. Others will do the same...
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Re: DIY acoustic panels with rockwool and a fan

Postby Nyiregyhazi » Tue Jun 16, 2020 1:58 pm

Hugh Robjohns wrote:
Nyiregyhazi wrote:Hugh, where is the evidence that tight weave acts as an impenetrable barrier?

If it was an impenetrable barrier it wouldn't work for its intended function, would it? What matters is that the pores are too small to let mineral fibres through... and that seems to be the case when using Camira Cara fabrics, and even more so using Camira Lucia which has a tighter weave.

This thread is also about having a fan to agitate the air right by it.

It was... ;)

I think we all understand where you're coming from. You must do what you think is right for your situation. Others will do the same...

What specific data says it doesn't let mineral fibres through? What about micro particles? I appreciate that my own stance is clear, but I think it's fair to scrutinise whether this is more than a feeling that the cloth seems to be an effective barrier. Probably 99 percent of rockwool use is sealed off away from people and this the kind of function it was tested for. To declare safety of use in which it is by significant air currents (with only a protective layer of cloth) is quite a big step. I think we should at least recognise uncertainty unless there is more direct evidence about how much protection cloth offers.
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