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The Comparative Safety of Rockwool, Fiberglass, and Organic Fibers (a review) Effects Pedals, Units & Accessories
Old 29th September 2011
Gear Head
Alonso Contreras's Avatar

What about mineral wool? I'm in a 3x3 m studio and i'm surrounded by these panels, like all surrounded.

I would normally not worry about it, but from time to time it itches. Considering that I'm 10 hours breathing it I do notice a change in the air when I go in and out from the studio.

Old 30th September 2011
Surrounded By Music
HDJK's Avatar
Originally Posted by tINY View Post

You're going to die

(it's a fact of life)


Old 13th November 2011
Lives for gear
Melgueil's Avatar

Wow - no comments for a while - great thread. I have been progressively installing more and more Rockwool-based traps (modular and corner DIY supechunks. I was beginning to be worried about it - o somewhat more reassured.

Q: Will putting foam in front of (or layered onto) these Rockwool traps in the corners do any harm, sonically speaking ? It would seem they would contain the loose fibers better (currently covered with light fabric). They would also look nice and, finally, I have left overs laying around from my high frequency treatment duties I could use. Keep in mind as I ask - my goals is indeed a rather dead room (it is small). Maybe the extra 2" of this foam material would actually marginally help the low end that the Superchunks were put in place to tame ?

Thanks in advance
Old 13th November 2011
Gear Guru
DanDan's Avatar

One could be hypothetically worried about the dangers of sound travelling past the borders of two different density materials. However I wouldn't sweat it, we readily accept fabrics which are in fact quite reflective at small angles. I reckon foam will be just fine. The pyramid stuff has a lot going for it.
Old 13th November 2011
Lives for gear

Originally Posted by Alonso Contreras View Post
What about mineral wool? I'm in a 3x3 m studio and i'm surrounded by these panels, like all surrounded.

I would normally not worry about it, but from time to time it itches. Considering that I'm 10 hours breathing it I do notice a change in the air when I go in and out from the studio.

if you are itching
your lungs are being cut to shreds
and you will have big breathing problems later on
if not cancer

do NOT stay in that environment

sue the idiot that put that stuff there
polluting the indoor environment
Old 13th November 2011
Lives for gear
Melgueil's Avatar

Thanks for your quick reply. My latest creation was a very thick trap into an empty corner under an extended desk / work area. I was getting headaches yesterday but that may have been from working directly with the Rockwool without a mask (not a good idea, I know).

As for the foam - it can be useful for high's. So far my ad hoc treatment has improved my Fuzz Measure results considerably. Will post about that in another thread so we don't veer off topic.
Old 24th November 2011
Gear interested

Which product is Roxul HT? Is it the same thing as Safe n Sound? I'm confuse.

Is "Roxul RHT" the product line?

Also, if it's not the same, how safe is the Safe n Sound?
Old 28th November 2011
Gear Head

I must say, I don't think there are majorly inherent dangers with any of these materials if handled with care. The distributor that sold me my JM 3# board and knauf ecose 6# board made it very clear to me: wear a mask, wear gloves and a jacket and tape their wrist openings of the gloves. Wash clothes used while installing the fiberglass separately from others. And cover the fiber board with cloth.

He argued with me that the relative safety between knaufs non-formaldehyde product and the jM product with formaldehyde was so small it's hardly worth mentioning... He said that the rigid board off gasses relatively little.

I followed his advice and didn't have any reaction to working with the raw materials... And no one in my family has had any kind of reaction to the roof where all of the traps are installed
Old 28th November 2011
Lives for gear
avare's Avatar

Originally Posted by soundoff View Post
I must say, I don't think there are majorly inherent dangers with any of these materials if handled with care. The distributor that sold me my JM 3# board and knauf ecose 6# board made it very clear to me: wear a mask, wear gloves and a jacket and tape their wrist openings of the gloves. Wash clothes used while installing the fiberglass separately from others. And cover the fiber board with cloth.

He argued with me that the relative safety between knaufs non-formaldehyde product and the jM product with formaldehyde was so small it's hardly worth mentioning... He said that the rigid board off gasses relatively little.
A big +1 to the voice of reality!

Really impressed,
Old 8th February 2012
Gear interested

I recently made 3, large 4' x 8' traps made with JM 3.5" rigid fiberglass. I built the frames with 2"x4", pedboard in the back, and wrapped the fiberglass with polyester batting (not so thick), and heavy canvas twice all the way around (8-3/4 ft. x 11-3/4 ft. Heavy-Weight Canvas Drop Cloth-634203 at The Home Depot)

I'm still worried that maybe the fluctuations caused by bass and if someone comes in contact with the hanging panels, mineral fibers will fall out and become a health hazard. I agree with one user who mentions coming up with a material to wrap or spray on the fiberglass that will keep the fibers intact, but is there any way to be sure of the safety factor?
Old 8th February 2012
Gear Guru
DanDan's Avatar

There is no way to be fully sure. Once doubt is there, it's there.
However, many people wrap overhead cloud traps in clingfilm or similar.
With poly batting and fabric outside of that, HF reflection is unlikely. To be sure of no HF reflection, one could angle the traps to deflect any potential HF to behind the listener.

Old 4th April 2012
Gear interested

Order from less dust to more dust

I would like to think that the dust in your system would be proportionately inverse to the amount of Roxul exposed and the amount of airflow in the room.

From all the posts I have read, this would be the order of choices of installations from less dust to more dust in your system:
1. Roxul with .6 mil plastic on both sides + fabric.
2. Roxul with .3 mil plastic on both sides + fabric.
3. Roxul with .3 mil plastic in the back, and fabric allaround.
4. Roxul with .3 mil plastic in the back, hair spray, glue, and fabric in the front.
5. Roxul with .3 mil plastic in the back, and fabric in the front.
6. Roxul with fabric allaround.
7. Roxul with fabric in the front and nothing in the back (not recommended).

Seems that option 6 is the most liked by the community.

The order of the list would be inversely proportionate to the amount of high end absorbed by the panels.

The readers have different rooms (from a 3x3x3mtx square room filled with Roxul to large studios), so the main difference and cause of dust in our systems would be air flow:

A. No air flow. Use of air conditioner all the time.
B. Indirect air flow from other rooms
C. Direct small amount of air flow from the window(s)
D. Unknown and variable amount of air flow from the window(s) since the window is directly heading landscape and there are no buildings blocking.
E. High window(s) air flow.

In my specific case, I have C/D air situations... because of that I am planning to go for option 2., but I will loose high end absorbtion. What happens if I combine the positioning of blankets in the walls with option 2.? Would blankets absorb what was not absorbed by the panels, and at the end, I would have a very healthy and excellent sounding room?
Old 31st October 2012
Gear Nut

Poll of personal experience

I guess the only way to find out is to have more personal feedback, positive or negative, from as many people as possible with installed acoustic treatment. Brief responses if possible.

Built a massive 8' high trap. I didn't have time to let the rock wool with phenolic resin binders off-gas. Got the headache in the morning. I am sensitive to such things, so, I am building my second bass trap with Knauf fiberglass insulation ( they also carry rock wool but supposedly less density reaches lower frequency when thick enough). Knauf uses safe ECOSE binder at nearly the same price as the phenol-based stuff( sweet)! I have no idea if the batting will generate dust but I hope the black garden fabric will be good enough to envelop it.
Old 11th July 2013
Gear interested

Thanks so much for this. I was reading the results of these tests on line but, it's great to have somebody break it down in simple English.
Old 18th February 2014
Gear Maniac
Areft's Avatar

Thanks for sharing this.
I used rockwool in my bass traps and now am getting worry because of the smell in my room (especially at mornings) and dusts which are visible under sunlight (Yep, I have a window in my studio)
Decided to not risk my health and use an air purifier like this;
Neo Tec.
Hope it works. If not, do you recommend to open the traps a wrap them in a thin layer of plastic?
Old 24th February 2014
Gear Maniac
Areft's Avatar

I feel the air purifier isn't enough as I can smell and sometimes see the dusts.
Can you recommend a way to solve this issue?
I've read people left these directions;
-Garden plastic or blanket
-plastic food cover
-poly batting
-thin layer of foam
-Hair spray
reliable input is so appreciated
Old 24th February 2014
Gear Nut

If there's no wrapping, definitely put one. I used the black garden sheet used against weeds. It does not feel like hard plastic, more like softer material fiber. Strong enough through but as long as you can feel the air when you blow through it .
I used Knauf batting, no knoxious binding agents. The Roxul will take a while to gas out, maybe months( not sure). run your house fan on continuously and keep your door open as often as possible.

Last edited by umarekawaru; 24th February 2014 at 02:48 PM.. Reason: more info
Old 24th February 2014
Gear Guru
Ethan Winer's Avatar


Originally Posted by Areft View Post
I've read people left these directions
Felt is a good material because it's thick enough to trap all fibers, yet passes sound easily.

Old 24th February 2014
Gear Maniac
Areft's Avatar

Thanks Ethan,
Felt should be good for holding dusts. Does it help the gas (smell) as well?
How long should I keep the windows open, if I want to get rid of this smell?
Old 25th February 2014
Gear Guru
Ethan Winer's Avatar


Originally Posted by Areft View Post
Does it help the gas (smell) as well?
Probably not. Hopefully it will go away over time.

Old 4th March 2014
Gear Maniac
Areft's Avatar

Thanks all,
Just want to report that I used a thin layer of white material, which dealers call it foam here. Just wrapped the rockwools in it and the same fabric and it does the job!!
I don't smell the same thing and my air purifier doesn't show much dust in the air anymore.
Good luck
Old 31st March 2014
Gear Maniac
Areft's Avatar

Old 31st March 2014
Gear nut

Originally Posted by Areft View Post
This is what I'm talking about;
Malaysia PE Foam Roll / White Foam Roll Supplier Distributor and Manufacturer
Polyethylene foam...
What you've got there is polyethylene, which is a closed-cell foam. The reason you can't smell any odors or find any particles is because it's effectively a solid material, ie: it has no breathability like fabric coverings.

I can't make a blanket statement and tell you it's going to be fine or, conversely, that it's going to hurt your traps, but I can tell you that material will be more reflective than traditional fabric-covered trap builds, and even moreso than just leaving the insulation in its thin plastic wrapping, since it's bound to be thicker - foam can't be cut to the thinness of plastic sheeting.

Now, if you had sucked out too much liveliness from your room with the traps, that reflectivity may be a good thing, But, you may also be reducing the low-frequency effectiveness of the traps as well. There really isn't any way for us to be able to tell outside of ballpark advice. Your best recourse would be to test your room with the coverings and without. That way you can see how much of an impact it is having and and whether any changes that may be present are worth dealing with for the scent and particle coverage.
Old 31st March 2014
Gear Maniac
Areft's Avatar

What you mentioned might be so true, but at some point I had to decide about my health or my level of perfectionism about my room acoustic. I can say that I don't hear a drastic change after the new covers. I had so much flatter effect before placing these traps and now I can experience some terrible bass tones at some points in the room, but everything become to its place at the sweet spot.
I hope to measure the call and response test soon.
Old 1st April 2014
Gear nut

Originally Posted by Areft View Post
What you mentioned might be so true, but at some point I had to decide about my health or my level of perfectionism about my room acoustic.

I hope to measure the call and response test soon.
Absolutely. I just wanted to clarify that I wasn't saying you needed to take them off or anything, just pointing out the potential effects they may have, both for you and anyone else reading, since no two spaces are alike. A happy medium is all most of us can hope for, so if your system works for you in all the areas that matter to you, that's the most important thing
Old 12th September 2014
Here for the gear
Originally Posted by audiovisceral View Post
After several threads here on the relative safety of rockwool, fiberglass, and organic fibers, I did a few days of digging through the medical literature to satisfy my curiosity. I thought I'd share a summary of what I found, as it may be surprising, particularly regarding organic fibers.

My personal conclusion is that, from everything I read, Roxul HT rockwool appears to be the safest material available. Although traditional forms of rockwool may be harsh, Roxul HT dissolves with incredible ease in the lung and is completely noncarcinogenic in even the most intense animal tests. It's relatively gentle and has great absorption characteristics.

The types of fiberglass we use also seem quite safe and, like with rockwool and organics, have absolutely no history of causing lung cancer in people or animals from even long term exposure. Typical fiberglass like OC703 is, however, much more abrasive than Roxul HT, and thus at least more theoretically capable of inducing lung irritation issues, particularly with high-level, unprotected exposure.

Organic fibers (like cellulose, cotton, and hemp), unlike rockwool/fiberglass, do not break down in the lungs or body at all. As a result, inhaled organic fibers too big for lung defense cells to ingest but too small to cough up can be more easily permanently trapped as irritants.

Whatever you choose, always wear a mask, gloves, and protective clothing when handling any of these materials raw and you should be fine. All the materials we use should be safe for normal studio applications. Studios/manufacturers that are still concerned about using any of these materials may wish to opt for a tighter weave fabric or a layer of polyester batting or other wrap glued to the insulation underneath. In fact, that might be good advice for anyone, but that's each person's call to make.

Research below includes animal breathing and injection studies, health reviews of factory workers, and rare and unusual case studies. It isn't meant to be exhaustive or definitive. I am also not a doctor or expert and this isn't medical advice. I do have a biomed background though, so if you have any questions/comments, I can do my best to clarify.


Biopersistences of Man-Made Vitreous Fibers and Crocidolite Fibers in Rat Lungs Following Short-Term Exposures,
Rats were exposed 6 h/day for 5 days to massive amounts of long fiber rock/slagwool (including one fiber by Roxul), and their lungs were studied over time. After 90 days, the residual fibers found in the rat lungs were broken down to 1/3 the maximum length macrophages (defense cells) can engulf and remove. At 9 months, retention of fibers was 1-6% compared to day 1. At 18 months, rockwool fibers were statistically undetectable. Asbestos was tested as well for comparative purposes. By contrast, it was not at all similarly digested, and at 18 months 29-47% of the original long fibers persisted.

Carcinogenicity Studies after Intraperitoneal Injection of Two Types of Stone Wool Fibres in Rats -- KAMSTRUP et al. 46 (2): 135 -- Annals of Occupational Hygiene
Rats were abdominally injected with two types of rockwool. One was a Roxul HT fiber. The other ‘typical’ traditional fiber induced cancerous growths, but the Roxul fiber had no adverse effect. These types of injection tests are important because they have higher sensitivity than breathing tests.

Chronic inhalation studies of two types of stone w...[Inhal Toxicol. 2001] - PubMed Result
Rats were hooked up to breathe the same two rockwools listed above. Exposure was 6 h/day, 5 days/wk for 2 years. Neither group developed any cancers. However, the ‘typical’ rockwool did induce some lung fibrosis/scarring. The Roxul HT did not.

Subchronic Inhalation Study of Stone Wool Fibres in Rats -- KAMSTRUP et al. 48 (2): 91 -- Annals of Occupational Hygiene
Again, a breathing test of the above two rockwools at the same dose but for 3 months only. In this case, no cancers or fibrosis were observed. Any inflammation was reversible, even with the heavy duty fiber.

The Biopersistence and Pathogenicity of Man-made Vitreous Fibres after Short- and Long-term Inhaltion -- KAMSTRUP et al. 42 (3): 191 -- Annals of Occupational Hygiene
Another two-year rockwool rat breathing test. No cancers observed. Risks with HT rockwool are deemed negligible to nonexistent.

Behavior of new type of rock wool (HT Wool) in lungs after exposure by nasal inhalation in rats
Roxul HT rockwool rat breathing study. The half-life of fibers was 34 days for all fibers and only 11 days for the longest (and thus normally most persistant and dangerous) fibers.


Cookie Absent
Researchers injected rats with highly dissolvable fiberglass to assay whether or not byproducts of fiber dissolution were likely carcinogenic. No tumors were generated. They concluded that the degree of carcinogenic potency of a fiber depends primarily on the extent to which it retains its fibrous structure over time, not its chemical composition.

Pulmonary response of mice to fiberglass : cytokinetic and biochemical studies
Comparison of fibrogenic effects of fiberglass and asbestos in rats. Demonstrates that fiberglass requires doses 10x that of asbestos to induce similar levels of fibrosis (scarring) to the lung. Unknown what type/durability of fiberglass was used.

Biopersistence of synthetic vitreous fibers and am...[Toxicol Appl Pharmacol. 1998] - PubMed Result
Comparative look at fiberglass, rockwool and asbestos in hamster inhalation. The very biopersistent fibers like asbestos and specialty high durability ceramics/fiberglass were carcinogenic, while the more rapidly clearing fibers, like normal commercial fiberglass equivalent to oc703, were not at all.

Cookie Absent
A one year fiberglass vs. asbestos breathing study in hamsters. Animals exposed to typical commercial fiberglass experienced only nonspecific pulmonary inflammation. However, exposures to a special, high durability fiberglass and asbestos were associated with lung fibrosis and possible mesotheliomas (lung cancer).

Science of the Health Effects of Fibers
OC's research paper references.

Fiberglass Case Studies

Wiley InterScience :: Session Cookies
Case study of carpenter who inhaled fiberglass unprotected for 41 years. Fibrosis, cystic lesions, and fiber deposition was noted. The authors conclude that this patient's heavy smoking history and long term exposure to fiberglass have contributed to pulmonary fibrosis. Fibers found had all broken down to short lengths, indicating the lung fluid was effective in breaking them down, but macrophages were not able to digest them. Cigarette smoking has an interactive relationship with fibers like asbestos-the asbestos worker who smokes has a much higher chance of developing lung cancer than does the non-smoker.

Clinical Pulmonary Medicine - Abstract: Volume 14(5) September 2007 p 296-301 Respiratory Disease and Fiberglass Exposure: Report of a Case and Review of the Literature.
Describes a 23 year old with an unusual adverse reaction to fiberglass. It is noted that rare cases of pulmonary fibrosis, acute eosinophilic pneumonia, and sarcoidosis-like pulmonary disease have been described after exposure to fiberglass.

Elsevier Article Locator
Studying 50 cases of sarcoidosis, an immune system disorder, 28% of patients recalled exposure to fiberglass/rockwool. Findings suggest that in susceptible people, mineral deposition from MMVF exposure may contribute to immune issues.


ATSDR - Toxicological Profile: Synthetic Vitreous Fibers
The full version of the 2004 US Government review on synthetic vitreous fibers aka manmade vitreous fibers (MMVFs), the group to which rockwool and fiberglass belong. It summarizes all available knowledge on how the body react to these fibers and any associated risks in relatively layman friendly terms.
One subsection of the above containing a referenced overview of all animal studies to date.
A good review article of epidemiological studies following MMVF workers long term. No ill effects have been noted except minor fibrosis among ceramic fiber works. Ceramic fibers are a specialty product that is far more durable and dangerous than any form of fiberglass/rockwool. Neither rockwool nor fiberglass workers were noted to develop the same effect.

Historical cohort study of U.S. man-made vitreous ...[J Occup Environ Med. 2004] - PubMed Result
Cohort sudy of 4008 women who were MMVF factory workers between 1945 and 1978. No elevated mortality or lung cancer has been observed.

Review article regarding manmade organic fibers (MMOFs). Indicates that cellulose fibers can be more biodurable in the lung than even asbestos, which in turn is many times more biodurable than fiberglass or rockwool. Cellulose is less carcinogenic than asbestos despite this, likely because it triggers far less lung inflammation.

Tumorigenicity of cellulose fibers injected into t...[Inhal Toxicol. 2002] - PubMed Result
Researchers injected high doses of wood pulp derived cellulose fibers into the abdominal cavity of rats. Tumors were produced. They state that cellulose fibers, along with many other organic fibers, are durable. Therefore, if inhaled, they have the potential to persist within the lung, and may cause disease.

Organic Case Studies

Diffuse lung disease caused by cotton fibre inhalation but distinct from byssinosis -- Kobayashi et al. 59 (12): 1095 -- Thorax
Case study describing a 66 year old man who had inhaled cotton fiber for 50 years at his workplace. His lungs demonstrated callusing of their lining and diffuse fibrosis. Strings of cellulose fibers were found in his lungs. According to the researchers, this was the first study to show directly that cotton fiber inhalation can directly cause diffuse lung disease unrelated to byssinosis.
MedlinePlus Medical Encyclopedia: Byssinosis
Byssinosis is an occupational lung disease in textile mill workers exposed to the respirable dusts of cotton, hemp, and flax. It is characterized by a chronic, asthma-like narrowing of the airways and caused by the bacteria which grow on the fibers.

anybody knows what Roxul HT is ? Is Roxul AFB Roxul HT?

Old 24th August 2017
Ok, just read this entire thread.... Here's a summary

1 - OP concludes logically there's no danger.
2 - OP with a new name takes crazy precautions with the reportedly safe material and has crazy reactions.
3 - Lots of people write about how scared they are of sound panels.
4 - A smart dude tells everyone how stupid they are for fearing this stuff.
5 - A new person comes in and says he's scared of insulation, and is feeling ill from it maybe.

Well I'm here to say, I'm also scared of insulation... but that stuff made of recycled denim, how can it be dangerous? It must be like hanging jeans everywhere, right? Also, it seems cheaper than other options... so does it absorb the bass?

Again, Ultratouch must be no more dangerous than any other cotton fabric, yes? Couldn't I just make myself an UltraTouch blanket and sleep in it?

These children are snuggling the Ultra Touch, so why can't we?

NRC seems too good to be true; (well, impossible, but let's not go there)

Old 25th August 2017
Gear Guru
DanDan's Avatar

It is confusing. The notion of plant materials rotting in the lung, e.g. cotton, for 18 months...... Versus glass fibre which feels scary but in fact dissolves within weeks.
Ultratouch- No matter how many times the question is asked, the answer remains the same. UT has high Gas Flow Resistivity. It will perform fine when thin, but not when thick.
Many do the same as yourself, look for a holy grail. There isn't one, although Polyester seems very promising. Also combined techniques such as steel sheet and fibre......
See Caruso Isobond or Autex and others. Alternative Absorption

Last edited by DanDan; 25th August 2017 at 10:05 AM..
Old 25th August 2017
Are there actually a lot of dust particles coming off the UT? Or is it like my jeans, which don't scare me?

UT is the Holy Grail at 3", which is enough for it to absorb very well down to 125Hz. Below 125Hz I think you would need a 10" thickness (a cube) or diaphragm.

But lets estimate the coefficient of UT down to 50Hz? If it's 0.93 at 125Hz, could we say it should be 0.3 at 50Hz? So I'll just add more panels, right? Wouldn't a steel sheet be reflective? Anyhow, I'll ask those questions in your other thread.
Old 25th August 2017
Gear Guru
DanDan's Avatar

So I'll just add more panels, right?
In area yes, in depth no. At greater depths UT becomes REFLECTIVE at LF.
Steel sheet is used in the RPG Modex Plate, see the VPR threads here on GS. Also check out BBC whole wall designs using cheap steel fibre and studding.
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