Hi there,

I'm working in a very small box room 5ft x 8ft and I recently added some absorbers (on the mirror points) and bass traps made from high density 30ml rockwool with timber frames covered with relatively thick Ikea fabric on the front and sides and Nylon material at the back, all stapled down well with a staple gun. I used a good dusk mask whilst making them outside however after hanging them and working in my room (albeit with a much more even frequency response) I started to experience a heavy chest and some shortness of breathe. I cleaned the room a number of times to get rid of any particles that may be in there air etc. but still experienced the problem. I took them off the walls and have since not experienced the kind of symptoms I had been getting but alas my room is back to being fairly unworkable!! I can't ventilate the room because there is acoustic glass over the window as I live on a main road.

Would you have any advice? is it that the Nylon I used on the back is too pourous? Should I recover the whole lot in some other kind of material? Has anyomne else experienced anything like this?

Many thanks,

Mark.

For this exact reason, I made my bass traps using compressed cotton or sheep's wool instead of rock wool.

You can source them from any decent Eco Builders Supplier. They come in exactly the same size and density as rock wool but being cotton/ wool they are 101% SAFE!

Best
tht

There is test data out there suggesting that organic fibres can be much more dangerous than the inert rock or glass ones.

The Comparative Safety of Rockwool, Fiberglass, and Organic Fibers (a review)

There is also data showing very poor performance of cotton in deep traps.

https://gearspace.com/board/2867011-post19.html

Sorry but there is a treasure trove of good information gathered here. Free to those who search.

Many of us wrap overhead traps in plastic film.
If there is a slight HF reflection through the fabric, a small angle will divert the offending reflection away from the listener.


DD

That would be my recommendation also.

Just to note though, you might have a allergy, but keep in mind that rigid fiberglass is used in ceiling tiles you see through out offices and homes. Also a lot of the cubicales you see in offices also have rigid fiberglass.

Regardless of what product you use - it is imperative that you be provided with a constant supply of fresh air to your space - that means fresh air in - stale air out.

IMHO that is your biggest problem here.......

Rod

It definitely sounds like an allergic reaction (I say this as someone that has some mild allergies to dust, and kids with more serious allergies to dust). The question is: what is causing the allergy? Is it the fiberglass itself? Or the fabric? (Did you wash the fabric before using it?) Or even materials (wood, glue, caulk, etc.) used for making the frames? Or could there be dust/particles trapped in the materials from where you built/assembled them?

BTW, I can say that I noticed that all of the insulation I used (pink fluffy stuff, mineral wool, and rigid fiberglass) all initially had very unpleasant odors that did seem to slightly effect my breathing (probably outgassing). But upon letting them sit out for several days, the odors and my breathing problems abated. So maybe let the absorbers sit outside the room for several days and try 'em again?

Thank you all so much for your replies, I should have posted weeks ago!

Rod, I have no doubt your right and I probably wouldn't have noticed it as much had there been fresh air throughout the room. Unfortunately I can't open the window anymore as I put acoustic glass over it.

I may well have an allergy although I've recently been through a house renovation where there was lots of rockwool, MDF dust and all manor of other dust and I never noticed anything throughout those hellish few months.

I'm curious about wrapping them in plastic film, what type of plastic do you use? Also when you say an angle, could you explain further?

Thank you so much,

Mark.

Clingfilm may be a bit too light to work with but otherwise would be great.
If such traps are used as clouds there is a possibility that some HF will be reflected down to the listener. If the trap is angled a little the reflection will hit elsewhere, e.g. behind he listener.
Similar situation to Desktop Reflection Revealed

An ETC would be ideal for testing if there such a reflection and if so, how loud/significant it is.

DD

It really does sound like allergy-induced asthma. If I were you I'd get rid of those traps and buy some alternative insulation products and before you commit to building traps leave the material in your room and see if it causes the same allergic reaction.

It's quite possible that there is outgassing taking place that could be averted as pointed out by Wyatt - this can happen with a lot of different construction materials - and the answer in that case is to allow the product to completely air out before placing inside of your space.

A fresh air source can help alleviate the problem somewhat - and eventually it will go away - but fresh air is really needed for another reason - and that is because in a well sealed room you begin (quite quickly in fact) to deplete the oxygen in the space - and this is not good for your health regardless of the room finishes.......

You should really think about getting at least some fresh air piped into your space - and remember that if all you do is install a small duct inlet - that you will not be able to move fresh air in unless you have an outlet - otherwise the fan will reach it's static limit (due to room pressurization) and just stop pushing air into the space.

If you really want to breath well - fresh air is key..........

Rod

Being an mechanical engineer/hvac contractor,I doubt it is the rockwool.The other materials maybe,but just ventilate the space.

Sent from my PC36100 using Gearslutz.com

Clear Plastic Sheeting from Husky | The Home Depot - Model CFHK0410C

Literally any type of plastic sheeting will work. You can grab it at your local DIY shop. Thickness of the plastic is measured by mils - and I believe I remember someone stating you probably wouldn't want to use anything thicker than 6 mil, to keep most the sound still absorbed. I'm not too sure on the facts of this, though. Perhaps one of the professionals could comment on this?

When DanDan said angle, he was referring to angling the entire traps, not the plastic. Just a small angle, but enough so that if you were to picture a mirror there instead of a trap, the sound would bounce from the speaker, and bounce away from your ear instead of towards it. Hope that makes sense.

Good luck

no thinner than 6mil for porous bass traps (LF absorbers) of which to reflect mid-HF specular content back into the room.



for specular broadband absorbers, if you're going to be wrapping the panel in a reflective membrane and then attempting to angle the panel to redirect the indirect reflection away from the listening position - then why even use a broadband absorber (wrapped with plastic membrane) in the first place? why not a large (with respect to wavelength) wooden reflector - which will minimize the broadband specular absorption within the room of which the redirected energy can be managed and reintroduced to the listening position at a later time?

Localhost, I appreciate your post, but he doesn't want mid-high frequencies reflected. I wasn't saying use thinner than 6 mil to reflect energy, he simply has an allergy of sorts to his traps - I was saying to use thinner than 6 mil to NOT reflect, and absorb closely to what he's getting right now. Pretty much, he likes the response in his room, but its irritating his throat. Thin plastic sheeting may help his allergy without affecting the performance of his bass traps.

Thanks for the graph localhost.
Perhaps someone could compare 6 mils with 0.14mm.
Quite a strong effect from a very thin sheet.

Thus the need for an angle.

However the fabric covering particularly if it has a polyester batting underlayer of 4-5mm will reintroduce some high HF absorption.

Hard clouds have been used, and hard side deflectors are common.
They typically divert a lot of energy into the back of the room, where it can be absorbed or diffused or both.

Given the enhanced effect at an angle it would appear beneficial to angle ZWER panels in all cases, soft, hard, or complex.

DD