Hi

I think Ethan should be able to answer this question but any other help would be great.

Again, I have a tiny control room (7"x9"x8") the hi and mids are pretty sussed with proper acoustic foam (second hand and CHEAP!)... just those darn bass frequencies to go!!!

The problem is that I am asthmatic and have been advised against Rockwool or fibreglass (regardless of the covering).

I need alternatives!!! Would carpet rolled up in each corner do the trick? Or anyother ideas????

you can apply the same principles with foam as with fiberglass.

there are cotton boards and polyester fibre boards as well

however, if you check the acoustic division of rockwool, named rockfon, or maybe better ecophon, they have glassfiber and rockwool boards which are suitable for this purpose and even fulfill standards/regulations for hospital use.

ecophon relly has nice room heigh panels which are more cleanable than even foam, which still collects dust in the much larger pores.

even in clean rooms, with extreme strict regulations in function of the number of allowed dust particles acoustic absorption can be applied.

in the food and pharmacy industry one also common uses absorption where dust particles are to be avoided.

those ecophone panels look as seemingly close painted panels.
they even exist in different degrees of cleanability.

but you can buy rockwool sealed in whatever foil too.

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The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

http://www.ecophon.co.uk/templates/eco_FamilyPage1____8776.asp

just check their site or contact them to find suppliers.
those things exist in room heigh wall panels too, with hardened edges etc.

but their are others too.
as said acoustics in dust sensitive/hygienic circumstances isn't that rare.

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The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

Joe,

> I am asthmatic and have been advised against Rockwool or fibreglass (regardless of the covering). <

I can't see why a suitable covering will not work. If the inner material causes problems, a suitable covering should keep that in place completely. Some fabrics are so thin and open that fibers can still escape, but that can be solved with cotton batting available at any decent fabric shop.

--Ethan

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The acoustic treatment experts

Ethan

So, do you think it would be ok if I wrapped each inner panel (christmas prezzie style) with a cotton sheet and then covered the frame with muslin??

I don't want to reduce the acoustic properties... or for tha matter die!

Quote sharpyJoe:

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The problem is that I am asthmatic and have been advised against Rockwool or fibreglass (regardless of the covering).

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Quote sharpyJoe:

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So, do you think it would be ok if I wrapped each inner panel (christmas prezzie style) with a cotton sheet and then covered the frame with muslin??

---

who gave you the first advice?
the doorkeeper?

I've written some extensive messages here at SOS about health and mineral wool.
As an astmatic > 5 decades and knowing mineral wool in about all existing versions i do have real live experience.

i only did the mistake now to take your question serious, and put in some energy trying to help you.
you even don't bother to notice that I did.

i even assume it to be possible that you're adviced wrongly,

this then should mean ethan's advice and your conclusions are perfect.

normally i don't dispute a medicin's advice, even when it was only to feel safer for him and yourself.
but i also know that astma and allergies triggering this astma exist in all possible degrees.
i also know that hygienic and dust free absorption materials and related specs for hospitals are not made for nothing.

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The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

Calm down Eric, you'll have an Asthma attack yerself in a minute...

Sharpy joe.

NO. merely wrapping it in cotton/muslin will not "seal" the small particle fibres and totally prevent shedding .

this is NOT a "clean room" or "Asthma safe" solution.

Eric did give lengthy valid advice earlier. ( in fact he almost always does.... it's just his taste in pizza topings i find doubtful )

To go even remotely near the Asthma Safe end of the scale you need to actually seal the surfaces of the mineral wool itself, then Wrap it in suitably finely woven acoustic material

Ethan's advice is valid only for the rigid types of material, such as used in his own products.... as these are essentially fixed materials anyway.

Whilst the US Dept of health, in it's "infinite wisdom" has declassified mineral wool as now NOT a carcinogen, it is still a potentially hazardous material , both for people that work with it regularly, and especially for people with Asthma.


Sealing the mineral wool is generally achieved by doping the outer layers with an adhesive, which then dries and fixes the outer layers of fibre in place... this makes it harder for the fine material to escape, and when you add the outer wrapping, you can generally consider it safe for use. however , I would add that it would still not meet true "clean room" specs... for which other materials should be chosen altogether... what I outline here is as good as the average DIY solution gets.


My Cheap and cheerful method is to spray ALL the surfaces, (edges as well ) with a fine mist solution of 1part PVA to 10 Parts water with a drop of Washing up liquid added. ( the washing up liquid alters the surface tension properties of the solution and helps it penetrate better. )

you need to thoroughly dampen the outside layers and then let it dry. because of the difficulty of supporting the material and letting all sides dry, it's usual to do it in a couple of applications... first all sides minus bottom edge, then once dry, all sides again minus opposite edge.

Once dried this fixes the outer layers in place but doesn't significantly change the Acoustic properties for anything other than extreme HF.

wrapping with appropriate material will generally restore the HF performance to roughly what it was prior to treatment... thus you end up with a much safer, effective broadband absorber/bass trap and less dust long term, and a safe environment for asthma sufferers.

BUT this is only effective for materials being placed where they will not be constantly or frequently disturbed as this will eventually break down the sealing.

devices to be placed in such areas should always be made from an alternate "safe" material.


For the record... In case anyone doubts this, I have a GREAT deal of respect for Eric's competence and abilities as one of the industry's more respected Acoustic Engineering consultants. I've seen some of his work..... he does it well.

Sadly, English is not his first Language, so it can take a while to 'read between lines" and I suspect that Diplomacy isn't likely to figure highly in his future career plans .

he's not a God by any means,., but you should at least read what he writes and give it some thought.

Best regards to All

Max

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if you don't know who i am, i aint gonna tell you.

max,

I’m a simple minded man from a simple culture, where people learn that it's a matter of simple respect not ignoring people trying to help you on one's own request.

that's independent of the nature and usefulness of the help in itself, but simply normal polite adult behavior related to the intent in itself.

i DO take people very serious based on respect.
love and being lovely are no synonyms.
which does not mean for me that they can't go hand in hand.


--------------------
The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

Eric,

I'm not too sure how I offended you. The reason I had not replied to your suggestion is because I had contacted your suggested company and was awaiting a reply... which by the way was... No. Their products are not suitable for low frequency absorbtion. It is safe, but eventually pointless.

I understand that it can be frustrating when you do some research and advise people in good faith. But I was not being impolite. I was following your advice... for which I thank you.


Kind regards
Fishybob

max,

and well meant thanks for the in-between nice words too.

correct is i shouldn't be a good diplomat, as such i'm guilty.
i prefer content over package when both disagree.

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The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

Fishybob

thanks very much for this reply.
and i DO appologize for this misunderstanding and my related response.

warm regards

--------------------
The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

I would add that some of the materials Ecophon do indeed seem suitable for fairly broadband absorption, and what might be described as bass trapping in a corner site.... however Ecophon seem blissfully unaware of this,.

however, I rather suspect this may be because many companies, when asked about bass trapping immediately think you're talking about tuned specific frequency traps, helmholtz designs, and other specialist tools... not plain old broadband corner devices......

in the sense of the specialist devices, no their materials are entirely unsuitable , however, I think it reasonable to think some of their stuff would do a fair job in corner mounted scenarios,.. the only issue being that I can't find a reference to anything thicker than @50mm, so it might be necessary to have two layers , or even two layers of different thicknesses, fixed together in a frame. then placed across the corners as usual.

that said... Ethan's own "mini traps " (The Real trap co, Distributed in the UK by Sonic distribution ) aren't much thicker than that either......

and I can say they definitely do the job well enough in many circumstances... and i would think are entirely suitable for asthma sufferers, as they use a rigid lightweight fibreglass panel, not a soft mineral wool panel, and in my experience they exhibit no shedding or dust creation habits... I've installed a significant number in situations I felt they were the best solution... always been happy with the results...... Again, as with all desings, they're not right for every job.... or budget... but used correctly , very effective.

the price is often a sore point for people this side of the Atlantic... but it is more or less in line with other similarly performing ready made, professional products... Yes going the DIY route can make them a LOT cheaper... but certainly not easier or quicker.

Max

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if you don't know who i am, i aint gonna tell you.

Hi Max!

Out of interest, Ethan is now selling direct to the UK/Europe to bring his prices down to more manageable proportions.


Martin

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YewTreeMagic

Thanks Martin,
I wish he'd tell me these things.... Sonic's site still shows it as being exclusively distributed by them in Europe... I did look to check, it didn't occur to me, despite my conversations with Ethan on this subject,and that of other distributors and retail outlets, to go and check the Real traps site.... I kind of assumed there'd be an E-mail shot or Announcement of some kind....





Ethan..... DOH! I guess I'll have to contact a couple of clients I'd referred to Sonic then.....

Do Sonic know yet??

Max

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if you don't know who i am, i aint gonna tell you.

Max,

> I wish he'd tell me these things <

I could have sworn I sent you an email a few months ago about that. If I didn't, my apologies - I certainly meant to!

> Do Sonic know yet?? <

I'm pretty sure they must know by now.

Seriously, I notified them a few days before I changed our web site but they never even replied. (I'm sure they were expecting it.) They may still have some stock, which is why our products are still listed. Though I doubt that because for the last three months they kept telling me they were out of stock and promised repeatedly to place an order which never came.

--Ethan

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The acoustic treatment experts

On sealing the rockwool front... could you not just put the rockwool in binliners (or anything else anyone wants to suggest - anything white or cream would make my life much easier!), fold the ends and seal them with masking tape, and then cover the whole thing in fabric (I was thinking curtain lining)...?

No Dan, that would place an impermeable layer around the rockwool. this would reduce the Hf absorption , and introduce undesirable resonance characteristics.

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if you don't know who i am, i aint gonna tell you.

Resonance in a bin liner? Scary stuff. This is all far too complicated!
Given that the whole thing would then be wrappen in curtian lining, surely the reduced HR absorption due to the bin liner wouldn't matter because it would be taken care of by the material outside of it anyway (which would be thicker than the bin liner)?
I'll go with the PVA solution, but a lot of these panels will be moved around, so I was wondering if there are any other solutions (hence the bin liner thought). I'm not keen for me and my studio users to be incarcinogating (to coin a word) themselves...
Ta,
D

Quote:

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Given that the whole thing would then be wrappen in curtian lining, surely the reduced HR absorption due to the bin liner wouldn't matter because it would be taken care of by the material outside of it anyway (which would be thicker than the bin liner)?

---

You recieved the correct answer.

No.

Quote Dan B:

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I'm not keen for me and my studio users to be incarcinogating (to coin a word) themselves...

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Dan,

The fact that you suffer from asthma is one thing, the dust from this (along with a world full of other things) can cause you to have an attack. That's a valid concern.

That being said, fiberglass is not a carcinogen, studies have taken it off even the "possible carcinogen" list.

It would be best if you weren't one of the people helping to spread false information on the internet.

Sincerely,

Rod

Dan and Rod et al.

US based studies (allegedly , so I've been told, lobbied for strenuously by the producers and building industry, although I have no evidence one way or the other, so treat it as hearsay... not fact ) have convinced the US health dept to remove these materials from the carcinogen hazard lists. and it's fair to say there's enough evidence to say that ingestion of the material of itself is not carcinogenic... Fair comment, it's essentially inert, not an active contaminant as it were... So I'd be quite happy about it on that front...

what's far less clear , and still of concern to many, myself included, is the question of physical properties related damage.

Basically the situation is that the material itself is fine enough, that it can travel deep into the bronchioles , and because it's really quite sharp because of it's structure, it can cause minute lacerations there, deep within the lung systems, whilst these are not of themselves carcinogenic, or generally life threatening , they can contribute to complications of respiratory illnesses, not only that but they some are fine enough to find themselves jammed into the openings of the alveoli and these two issues could lead to enough scar tissue formation to significantly reduce the gas transfer efficiency of the lungs.

the trouble is that exhaustive and conclusive studies in to these issues are long, expensive and difficult, and of course involve knowing enough to say who could reasonably be used as a "control " and who would be a case for investigation of active damage.

SOME of the data from studies of miner's diseases relating to inhalation of mineral dust is probably reasonably applicable to the issue.....

There is insufficient pressure or driving need ( according to the accountants and beaurocrats ) to investigate our particular field, or probably that of insulation installers, as thoroughly as is necessary to be able to state categorically one way or another about some of these materials overall hazard status.

So the responsible attitude is to ,consider them potentially hazardous, and treat them as such. But not to be reactionary , not to be yelling and screaming about carcinogens , just treat them with all reasonable care.

From the Acoustic consultants and installers position , as well as the DIY enthusiasts, especially those regularly exposed in handling and cutting this SHOULD mean wearing protective face mask suitable for fine particulate exposure, and in all cases ensuring a minimisation of shedding once installed.

this stuff is by no means the most noxious substance on earth, nor is it likely it's going to kill the average home studio user, or even a professional commercial one, but it does pose some risks, especially to those with already extant respiratory issues and we should minimise those as a duty of care.

look at it this way.... petrol is both flammable and poisonous, we use it daily, but we take care not to smoke around it, or drink it, and to keep it in suitable containers. that's all it is... just reasonable care.


Max

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if you don't know who i am, i aint gonna tell you.

Max,

Understood, and I agree completely with the necessary care to be taken while working with this material. I always tell people to properly protect themselves while working with this (or any other) material.

However, on the issue of studies done - there were extensive studies done during the 80's that led to classifying this material as a possible carcinogen by the early 90's. The studies were continued through the 90's into the early 2000's until finally enough data was gathered to prove that there was no substantiation of the claim. It was then taken off the list.

I would consider over 20 years of studies on the subject - with today's testing methods - stringent enough to be able to determine probability.

The fact that it was claimed to be a possible carcinogen - and to maintain that status for over 10 years while the studies continued (before being taken off the list) is reasonable proof that the industry was not able to influence the results.

This is not a case of someone hiding a smoking gun - but the myth continues to spread none the less.

I can provide you a link or 2 to medical and govt comments regarding this (if you wish) that support my statements. I have not been able to find any recently published data by any credible sources pointing to any postition other than what I state.

If you know of any - I would be happy to review their data.

Sincerely,

Rod

Hi Rod,

That is why i made it very clear that the question of the lobbying should be considered as hearsay... I had been told this, by several people, but had seen no evidence to support this,

The reason I mentioned it was that i couldn't see any reason for people that benefit from using the material cynically questioning the studies impartiality .

I would have expected more to be of your position than the conspiracy theorists.... if you see what I mean... so in the interests of a completely balanced view... i mentioned it, but clearly WITH the caveat that it's unsubstantiated.

Max

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if you don't know who i am, i aint gonna tell you.

Quote Max The Mac:

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That is why i made it very clear that the question of the lobbying should be considered as hearsay... I had been told this, by several people, but had seen no evidence to support this,"

---

\

Max,

I hear you - and I suppose this is a personal thing for me - but the very fact that the people making these claims cannot provide any evidence is why I avoid mentioning it.

To mention what they say is to give it some semblance of reality - even if this is not the intent.

There are thousands of people who will only remember 1/2 of what they read.......... the problem is - it might well be the wrong 1/2. And then they're passing on that "Max said..................and he really knows what he's talking about"

Nuff said - letting it go now.

Sincerely,

Rod

Many thanks for all the information.It's good to hear rockwool isn't carcinogenic. My apologies for spreading mis-information, but no-one can verify possibly every piece of information they come across or would reasonably repeat.

I don't have asthma, but am nonetheless concerned about particles of rockwool in the air (and my lungs) given that I will be moving the traps around occasionally and given that I'll be in the room with them for extended periods of time.

Presumably taping a bin-liner across the back only of a DIY corner bass trap wouldn't affect its absorption properties, since the high frequences (the only ones that would be stopped by a bin liner) would already have passed through the trap and just be reflected back into the rockwool....?

There's still the issue of the fronts. I've treated the rockwool with a quick lick of very diluated PVA glue, but whilst this may help it's not totally effective (especially since I then have to squash the rockwool into the trap which breaks down the pva coating. I've then covered the front with a double thickness of curtain lining cotton twill (which is lamentably thin...). Hopefully this is sufficient.

Comments welcome. Thanks in advance.

D

if you make the traps the right size, the rockwool doesn't require much in the way of squashing.

the application is normally done with a plant sprayer, and thoroughly, it can be repeated once in the frame and before you wrap with material.


i would still advise against the bin liner... it WILL reduce the effectiveness, because no matter which side you place it on, it is still an impermeable layer.


it's not a question of bass being stopped by it, more of it allowing the pressure wave to grab hold of the trap and induce resonance , thus reducing the efficiency of the trap.

so don't do it.

Max

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if you don't know who i am, i aint gonna tell you.

Quote Dan B:

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Many thanks for all the information.It's good to hear rockwool isn't carcinogenic. My apologies for spreading mis-information, but no-one can verify possibly every piece of information they come across or would reasonably repeat.

---

It's impossible to check all info, as such it's the responsibility of the writer not the reader to give honest substanciated info.
It's plain impossible for the average reader to find all related documents and studies. And if one couldn't trust summaries of so-called experts why then do they exist?

In this Topic Jeff (Auralex) linked (as info) to a page combining one site of the argument.
When reading that page, as a layman, one comes never near a glassfiber board anymore.
Rod gave a very powerful reply by writing to the page author.
It's a sticky Rod made in his forum: http://www.recording.org/ftopict-21013.html

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The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

Quote Max The Mac:

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i would still advise against the bin liner... it WILL reduce the effectiveness, because no matter which side you place it on, it is still an impermeable layer.

---

Max,

Aren't there different types of bin liners?
Have you ever measured the difference?
This is just a question.

Correct is certainly that it's an impermeable layer, which physically distinguishes from being acoustic transparent by 100%.

Packing them in foil is done a lot, even with commercial absorption material (mineral wool) mostly around 30 microns PVC or polyethylene foil. I think some bin liners aren't heavier than that.
This "one use" (didn't knew correct word) cheap foil one sells to protect furniture during painting certainly isn't.

I agree that uncertainty speaks for not doing it.

I've done some extensive testing in a lab on mineral wool without and covered with foil. Out of my head between 10 and 12 m2 samples, should have to check. And with the same foil clamped between perforated sheet and the wool, as well as the wool with the perforated sheet without the foil.

As shown by 1/3 octave lab measurements, when the foil can vibrate freely as when laid free directly on top of the sample, the effect is the typical effect of hardly none in the lows to increasing in the highs.

However when the same foil is clammed between perfo sheet and the wool, the effect of the same foil can even become the reverse with more negative impact on the lows than the highs.
This gives some scary effects which hardly anyone has ever seen and one finds it nowhere described.

Therefore a glued foil is more risky and introduces more uncertainties than just when the wool is packed in it.

But I also agree, I never tested the difference using boards on a cavity.

I'm not sure yet if I want to release those measurements themselves on the net (expensive & time consuming studies and typical lack of respect for copyright on the net. One rarely will find the original source of absorption data on the net if not from the manufacturers site).


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The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

For the ones interested.

The ISO EN standard (covering all member states), latest edition, now forces any absorption measurement to be executed with edge screening also for standard measurements.

If not doing this, for whatever accepted reason, one is forced to calculate the edge surface in the calculation.

This does not NOT mean this covers exactly the edge effect and diffraction, but sanctions a bit non-screened measurements.

The ASTM with much smaller samples, as such more significant influenced by this edge effect in the 2000 edition does not have this obligation.
However there is a newer (I think 2002 edition) which I don't know yet if this is altered too.

Anyhow those stipulations and their application can significantly influence comparisons of different absorption measurement data ALL expressed as absorption coefficients as per Sabine.

Jeff do you have the 2002 ASTM edition?

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The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

Max,

To prevent misunderstanding. I was not disputing your spray method which certainly works.

I've a series of measurements where Rockfon ceiling tiles are sprayed. (New: measured, sprayed and dryed then measured again, sprayed .... and so on) And even when the fiber covering such tiles is already very dense, it's surpricing how much layers of light spray paint can be used before noticing it on subsequent measurements.

Doing the same with brush or roll and it's damaged of course.

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The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

Quote Eric Desart:

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Max,
Doing the same with brush or roll and it's damaged of course.

---

So painting the pva solution on wouldn't work? Oh dear... I was having difficulty getting the sprayer to work with the pva solution, and ended up painting it on ... Argh! What have I done? And what consequences will this have? It was only an extremely diluated solution.

Dan

Dan,

I don't know exactly what a PVA solution is, so you better ask Max.

The idea is the whatever you put on top does not form a closed film. Dat you still can blow trough it.
But I should gamble, not knowing exactly what you talk about.

For me it always surpriced me how much gasflow resistance a surface can have.
If you use a paint roller on an absorptive ceiling tile you really lay a closed film on top and that's bad.

Which also shows that the mass of such a film (compare with foil) can have different effects on absorption depending on how they are connected with it.

I think Max can help out better here for your PVA.

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The important thing is not to stop questioning. Curiosity has its own reason for existing ............... Albert Einstein

Pva Solution

1 part PVA
10 parts Water

1 moderate drop of washing up liquid per Litre.



Choose a plant sprayer with a variable or relatively coarse Spray pattern.

alternatively, Some of the hand held trigger spray dispensers for products like "Pledge with orange oil" are suitable for this work....

you just have to refill them more often

also rinse thoroughly through with warm soapy water every so often to help prevent premature clogging.

eventually they give up, but generally you can get a dozen panels easily done


What's even better is using a glue called "Adiabatic resin" as it has more long term impact resistance.

As Eric says, the important thing is that this method fixes the fibres, but doesn't significantly change the Gas flow impedance.

you need to get it thoroughly damped, but not dripping.... if it's dripping off, it's likely to be too thick and form a closed membrane.

Best regards
Max

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if you don't know who i am, i aint gonna tell you.