Green Glue tests

Note: This is a post I very recent received via PM and my PM reply, but I do think this belongs in the forum. I preserved strictly the original formatting (incl. bold sentence) and text.

I removed the name of the poster. He/she can decide making that public or not. I also gently want to ask not to use PM for private free concultancy. The number of post I collected as such, and via Email, over the years is much too large. I started out with answering them, then writing gently my being on public forums was not meant to find private help and that the forum was meant for questions, and then I stopped answering at all, which may look impolite of me, but I have only so much energy to share. And in public forums the best thing is to ask in public, since there are a lot of judges present, and people can have different opinions. Plus: there can be people better placed than I am to answer certain questions.

XXXXX wrote:

Hi! Sorry to bother you like this, but I'm trying to decide whether to use GG or not... I've asked, in other forums, if there are any independent tests of GG, but all I've got is the tests ordered by GG themselves and I have to say, I don't count them as independent tests. My problem is that for every other "expert" I ask, I get about 50% of "GG is useless" and "GG is the thing". The last expert I asked works for a fairly large acoustical engineering firm in Oslo, which amongst other things works on the new opera building in Oslo. He said he never recommended GG for any customer (for sound insulation purposes). Now, why would he say a thing like that if GG really is working? I'm sure a lot of his customers have more than enough money to use on their projects. I'm getting crazy trying to decide about this GG stuff...

XXXXX, Normally you should ask questions in the forum that I and/or others can reply for all. That's the idea of a public forum. For me PM is meant for private stuff, not free consultancy. You noticed what I wrote related to GG on lot of spaces here in the forum and elsewhere. Not accepting these official measurement reports from an official lab, because they are ordered by Green Glue as a commercial company, is not clever to say the least. That way you can question 90% of all official lab measurements, absorption AND transmission loss, ever executed, and they can close their doors. How do you think they finance their operation? Even university labs are significantly financed by work for the industry. These labs are accredited versus official standards and/or regulations, and do not risk there name. They just execute measurements as per official published standards. If they shouldn't competitors should gladly make use of that, proving these measurements can't be trusted. Only few companies invested that much in measurements to prove their point. I wished there were much more of these. I also know the designer of the stuff (not on a real personal basis), and my impression is that of a real scientist, with the attitude I expect from a scientist. I don't know official measurement by others. I've used GG. I know the theory AND the material. One can discuss if you find it worth it in function of cost/performance ratio or not, which is also depending on your goals and purpose. But someone telling that GG doesn't work or is useless is NO scientist whatsoever, not worth to carry the name acoustician or expert, no matter how big his/hers name. What GG does extremely well is damping resonances with CLD (constrained layer damping), which is a for ages known and described physical phenomenon. Hence it's not "It" nor "Useless". It's very good in what it says it does, and I can confirm that from practical experience. I hate this kind of acoustics in slogans. Something "Is", whether that "Is" is useful for your specific purpose must be weighed to other parameters involved, which among other things, includes cost in absolute sense and cost efficiency. Please further questions in the forum please. Kind regards Eric

That exchange is truly fabulous on many levels. Thanks for posting it Eric. Also, with your permission I'd like to use this line:

For me PM is meant for private stuff, not free consultancy.

I have my own version, but yours is better and shorter. --Ethan

XXXXX Just to add something to my previous post: What surprises me is that once and a while, people start disputing data from a company investing a lot in official measurements and offering a lot of useful and scientific correct data and explanations, while simultaneously other companies substituting real scientific data by stories and pseudo-science aren't questioned at all. A reminder of some previous posts where John suggested a possible alternative for GG, feeling our related posts weren't balanced enough: http://www.johnlsayers.com/phpBB2/viewt ... ght=#65401 This is about ASC where Art Noxon founder and President is generally known and respected as a very knowledgeable acoustician, whom also publishes a lot. Rod Gervais triggered by John's post, typically keeping an open mind, takes the initiative to email ASC to ask for measurement data substantiating all related claims (and there are some questionable design pictures on their site). For me the related claims are still only covered by the notion stories (since no measurement data is available), and there is still something "physically acoustically" for which I gladly should give them the benefit of the doubt (too mathematical to explain), and for which it's even possible for me they aren't aware about the influence of the effect themselves (it certainly does not appear anywhere on their site), and which, if true certainly does not support their claim of being engineered and knowing it all. So what does ASC writes on their site about their alternative WallDamp system (I highlighted the bold characters): http://www.asc-soundproof.com/walldamp- ... double.htm

ASC wrote:

ASC is known worldwide for the best audio acoustics, and our soundproofing is no exception. WallDamp is ideal for high powered audio environments where quality counts. Unlike other damping systems such as "Green Glue", our product is engineered to give you a known result based on a known quantity of damping material.

1. They specifically refer to Green Glue, without substantiating anything related to GG (nowhere on the ASC site), which can only been explained by considering them a serious threat.
2. They suggest that Green Glue has little idea about known results versus quantity.
3. They suggest that their "engineered" product gives known results based on known quantities (hence they know all details how to advice customers in function of targets).

This are damned BOLT statements. But he, if it represents the truth .... honest = honest. Thoughts about the above:

1. No explanation needed. Commercial hype, let's just question the competition.
2. Green Glue has executed a lot of measurements,and discussed them in groups, publishing results in order to describe the effect of GG panel coverage tested in several manners, the effect of using less per board but more gypsum boards layers and so on. Basically they did everything a user could like to know in function " how to apply it in function of quantity (cost efficiency) versus to be expected result. What is the effect of using more, standard or less coverage in %, and so on, on the TL of the wall (non-linear relationship investigated by them). The alleged lack of the GG knowledge related to "quantity versus to be expected result" as stated by ASC is misleading and wrong.
3. The cynical part. While ASC suggests to know it all, telling Green Glue doesn't, Rod Gervais got reply on his request for measurement data from ASC, which he shared at Studiotips. ASC does NOT have one single lab measurement, and they told Rod that they plan to do some in the future. Not one single measurement was presented to Rod enabling him to check the truth of the above BOLT (dishonest?) statements.

Seen the statements of ASC in the light of the above, I even question their ethics here, and call this nothing more than cheap marketing hype, a company as ASC unworthy. Now the interesting part is that Green Glue is a very recent product (wild guessing: some 3 years), while ASC WallDamp is much longer on the market. I don't know dates, but in as far as I remember it was always there since I visited the net around 2000. Hence there is no reason whatsoever for ASC not to have this measurement data available, and their claims never, until this very day, were supported by official data. And no other comparative acoustic data is to be found either, only stories. And I'm still NOT the least interested that anyone uses Green Glue or not. I was perfectly clear about that in my previous post. That's a decision people ought to make for themselves in function of their own goals, purpose, needs, budget and whatever. Most walls build worldwide are build without GG, and I assume fulfill their proper purpose.

Good post Eric. :D cheers john

John, :) Many thanks ..