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Quote from Rod Gervais regarding Green Glue
Old 1 week ago
  #1
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Quote from Rod Gervais regarding Green Glue

I noticed this statement by Rod Gervais while doing some research on Green Glue.

From Rod:

__""Sorry - you can use 2 layers of drywall with green glue in between for about the cost of 3 layers of drywall - and get the result of 4 layers of drywall in return.""__

Hopefully Rod will chime in on this for clarity..

Is he saying that he's confident that using 2 layers of (presuming 5/8") drywall with Green Glue installed between them is the equivalent of using 4 layers of (same thickness) drywall without GG, of course..?
Old 1 week ago
  #2
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??

Never heard that 2 sheets of 5/8 drywall with GG would perform this way//
Old 1 week ago
  #3
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Jeff Hayat's Avatar
 

I cant answer you, but whoever picked that shade of green for their website need to be HD&Q

Cheers.
Old 1 week ago
  #4
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avare's Avatar
 

Compare TL-92-071 in IR 761 to the first test 0n Green Glue's test data. Rod is right.

Andre
Old 1 week ago
  #5
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I asked because it is very interesting to read the 'all over the place' opinions on Green Glue..from-'it does nothing' all the way to this quote from Rod where (assuming proper application) two sheets with GG between will equal the result of 4 layers, mass only.

And, as for application..That seems all over the place from site to site, too..

I've seen a few videos..i think from the GG people, where the application technique seems way way haphazard with no rhyme or reason to keeping track of repeatable amounts, or, pattern of application...the guy was squirting the stuff all over the place..

wondering if there is resource out there that shows minimum effective amount in a repeatable, organized pattern?
Old 1 week ago
  #6
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Quote:
Originally Posted by Pchicago View Post
I asked because it is very interesting to read the 'all over the place' opinions on Green Glue..from-'it does nothing' all the way to this quote from Rod where (assuming proper application) two sheets with GG between will equal the result of 4 layers, mass only.

And, as for application..That seems all over the place from site to site, too.
Why are questioning this AFTER I posted test data on similar walls showing the improvement of Green Glue? I chose that TL because it has extra mass compared to the NRC test. It also dampens MAM resonance.

Use Green Glue's direction's.
Old 1 week ago
  #7
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Quote:
Originally Posted by Pchicago View Post
I've seen a few videos..i think from the GG people, where the application technique seems way way haphazard with no rhyme or reason to keeping track of repeatable amounts, or, pattern of application...the guy was squirting the stuff all over the place..

wondering if there is resource out there that shows minimum effective amount in a repeatable, organized pattern?
haphazard IS the proper way to apply GG.

Hey ... can appreciate the skepticism ... I was too when we were designing our new Mastering Control Room.

Rod, Avare, SoundMan, Gulfo [and others] were incredibly helpful throughout the process.

We used GG for all Walls and Ceiling [dual-5/8" Type-X]. The final result was nothing less than stunning. [mind you ... extreme attention to details].

Avare points you straight to THE Documentation and Lab Reports, and cuts through all the 'opinion' BS.

As for GG application ... some people asked whether the GG should be 'trawled' for a 'predictable' spread. The official word ... NO.

The real question is 'how many tubes/4x8 sheet'? We didn't go crazy about that ... the results still amazing.

Considering the Cost ... Doubling the Drywall [rather than GG] has much to do with LABOR costs [those 5/8" are HEAVY].
Old 1 week ago
  #8
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Quote:
Originally Posted by avare View Post
Why are questioning this AFTER I posted test data on similar walls showing the improvement of Green Glue? I chose that TL because it has extra mass compared to the NRC test. It also dampens MAM resonance.

Use Green Glue's direction's.
Huh?

I don't see anything in my post that suggest that Im questioning anything. I was clearly reinforcing some fairly normal dismay at the distance between reactions to Green Glue and results that show up on the web, the extremes..and Im a little bit dismayed at the strength of your response, too.

I've also read several times that you can back off a bit on the amount of Green Glue per sheet of 4x8..anyone have any input on this?
Old 1 week ago
  #9
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Quote:
Originally Posted by RJHollins View Post
haphazard IS the proper way to apply GG.

Hey ... can appreciate the skepticism ... I was too when we were designing our new Mastering Control Room.

Rod, Avare, SoundMan, Gulfo [and others] were incredibly helpful throughout the process.

We used GG for all Walls and Ceiling [dual-5/8" Type-X]. The final result was nothing less than stunning. [mind you ... extreme attention to details].

Avare points you straight to THE Documentation and Lab Reports, and cuts through all the 'opinion' BS.

As for GG application ... some people asked whether the GG should be 'trawled' for a 'predictable' spread. The official word ... NO.

The real question is 'how many tubes/4x8 sheet'? We didn't go crazy about that ... the results still amazing.

Considering the Cost ... Doubling the Drywall [rather than GG] has much to do with LABOR costs [those 5/8" are HEAVY].
Thank you..interesting that you seemed to have backed off on the amount of GG,,,im assuming your mention of --"we didn't go crazy about that..the results are still amazing"-- is referring to maybe using a little bit less?

But, having been in the trades for many years, it still strikes me as odd that 'haphazard' application has a actual reason behind it..

it is much easier to track the amount of product you're using, and, perhaps, create more consistent and predictable sound tempering results, if you create some sort of organized scheme for application..-bead size and pattern..i see so many different approaches to this as I read and look at images.

And i think, in the most honest sense..the GG company does want to sell as much product as they can...what company doesn't?

It would be very interesting to see a well executed test using Green Glue in different amounts.., like, 1 tube per sheet, 1.5 tubes per sheet, 2 tubes per sheet..maybe a couple of different tip snips that alter bead size..

Has anyone ever come across a well planned test like this??

As for the results Avare pointed to, I read them all and appreciated seeing them
Old 1 week ago
  #10
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avare's Avatar
 

Quote:
Originally Posted by Pchicago View Post
Huh? I was clearly reinforcing some fairly normal dismay at the distance between reactions to Green Glue and results that show up on the web, the extremes. Im a little bit dismayed at the strength of your response, too.
You reinforced confusion about Green Glue and its effectiveness AFTER I gave clear objective information.

Andre
Old 1 week ago
  #11
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Quote:
Originally Posted by avare View Post
You reinforced confusion about Green Glue and its effectiveness AFTER I gave clear objective information.

Andre
I'm not gonna do this, Avare. Im not sure why this got you so angry.

What i did was express some dismay at the extreme range of opinions on this product..nothing more.

I read the results you posted, they were very interesting...and i still have more questions on this topic..hopefully you can help. Thanks
Old 1 week ago
  #12
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Part of the problem im having with the recommended ( by Green Glue co ) application technique is that, in my experience with a huge variety of products like this over the years..glues, mastic, loose thinset, even something like Tightbond. When you apply product unevenly..crossing over, or, doubling (even tripling in the case of the GG recommended technique) your application lines..You create high points. And unless you spread it (and even if you're using fasteners) sometimes those high points can remain under or between sandwiched materials, especially large sheet material like drywall where you cant lay into a screw

..I've seen this happen even with clamping..It is extremely common with drywall..Ever remove a sheet of drywall that has been glued and screwed?? It's very common to see areas where glue has been compressed very unevenly...due to inconsistent screw sets or whatever..i would think, with GG, you'd be going for a consistent level of product

In the case of drywall..this becomes a very relevant issue because of the fine line between a properly set drywall screw and an improperly set drywall screw..ie: paper tears...So, high points can and will remain because you can only torque a screw so much in drywall before failure.

Very difficult to torque a drywall screw to mitigate uneven glue/material points in any situation, let alone across very large sheets of material..If this was two pieces of 1x4 pine being glued together...very easy to apply enough pressure to kill the high points..large sheets behave much, much differently

This is one reason why I'm a bit skeptical about the recommended application technique..it's the crossing over of the beads..which seems very unnecessary to me, not wise, even. Understanding of course that GG is a bit soupy..it still will happen..again, very tough to torque a drywall screw to compress a product like this between two large sheets..without tearing.
Old 1 week ago
  #13
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Quote:
I'm not gonna do this, Avare. Im not sure why this got you so angry.
I'm not so sure that Andre is angry.... you'll need some more time to get to know him. His comments are generally very terse: short, pithy, to the point. And always accurate. But that can be mistaken for anger, or a whole range of other emotions. Maybe he's more like "mildly miffed" that you didn't seem to be taking his very accurate information into account. But anyway, you really should listen to him: he's probably the best, most respected acoustician here on GS, and in many other places too! Even if he does sound angry some of the time!

- Stuart -
Old 1 week ago
  #14
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Quote:
When you apply product unevenly..crossing over, or, doubling (even tripling in the case of the GG recommended technique) your application lines..You create high points.
That's correct. That's how they want it to be applied. If you read the instructions on the package, it's quiet clear that this is what they recommend, and I can understand why. They coverage recommendation is also stated quiet clearly. I don't have it with me right now, but if I recall correctly, for best effect you should squirt on three tubes per 4x8 foot panel of drywall, or you can cut that to two tubes and still get something like 75% of the full effect, or one tube and get half the full effect. I'm hoping somebody can correct me with the actual numbers, as I'm just working from memory here. I always recommend full application.

Quote:
And unless you spread it (and even if you're using fasteners) sometimes those high points can remain under or between sandwiched materials, especially large sheet material like drywall where you cant lay into a screw
I'm not sure if you have actually used the product (GG), but I think you'll find that when you do, you'll see that your concerns are unfounded. It's very "gooey" is probably the best word, and won't end up leaving humps and valleys in your drywall. The overlapping beads will "squash down" (for want of a better term) quite nicely. Your drywall will end up quite flat and smooth.

Quote:
..I've seen this happen even with clamping..It is extremely common with drywall..Ever remove a sheet of drywall that has been glued and screwed??
Green Glue acts nothing at all like construction glue. It never actually hardens, to start with. Because it isn't glue! I sometimes wish they would have found a better name for the product, because it has nothing in common with adhesives, and cannot be used as an adhesive. And it should never be clamped either. Just apply it as instructed, then screw or nail the drywall in place as normal, and that's it. It will work just fine, doing what it does best, which is "constrained layer damping".

Quote:
Very difficult to torque a drywall screw to mitigate uneven glue/material points in any situation,
And it would be a big mistake to even attempt that with Green Glue. In fact, I can't even see you ever needing to do that! If you did, it would be because you didn't follow the application instructions correctly...

Quote:
again, very tough to torque a drywall screw to compress a product like this between two large sheets..without tearing.
There is no other product like this (despite the claims from some manufacturers...), and it would be a major mistake to attempt to "torque a drywall screw to compress" Green Glue. I've never heard of anyone needing to do that.

Quote:
This is one reason why I'm a bit skeptical about the recommended application technique..it's the crossing over of the beads..which seems very unnecessary to me, not wise, even.
It is very necessary, actually, and very wise. If you were to lay it out in nice neat rows that never cross over each other, you'd be creating a pattern that could adversely affect how it works. I'm speculating here, but it occurs to me that a regular repeating pattern could cause the same type of issues that regular repeating patterns cause with diffusers...

Random application is what the manufacturer recommends, and that is what has been tested in their own labs, as well as in independent labs, and shown to work. I would presume that they were smart enough to test other application patterns, and found that they did not perform as well... They have pretty smart engineers there, and I'd bet good money that they tried out every possible method for improving the performance of their product, in terms of both coverage pattern and coverage percentage... and "randomly squirted 3 tubes per panel" turned out to be the best. It sees logical that if there was another pattern that would make the product perform even better than it already does, they would have published that too. Why would they recommend an application method that doesn't bring out the best in the product?

Quote:
it is very interesting to read the 'all over the place' opinions on Green Glue..from-'it does nothing' all the way to this quote from Rod
I've never seen anyone say that GG does "nothing at all". It is very effective, as shown in numerous lab tests, and numerous real-world studio builds. What I have seen is people complain about the price: it ain't cheap! But this new data that you highlighted puts that in a whole different perspective: Like some others, I had always assumed that a full application of GG was the equivalent of one additional layer of 5/8" drywall, so the cost/benefit was questionable from that point of view: it worked as advertised, but cost a lot of money. But it turns out I was wrong, and it's actually equivalent to more like TWO additional layers of drywall, as confirmed by Andre. That changes the entire "cost benefit" equation quite a bit! So not only can you save on the material and labor costs of putting up those two extra layers, you can also save an inch and a quarter of total thickness in each leaf of your wall, so likely 2 1/2 to 5 inches in a typical studio where GG is used on both leaves of all walls. That's substantial, for most home studios! Gaining 5 inches of room length and width, and 2 1/2 of height, is very much worthwhile. This puts GG in a whole new light for me: I'll be recommending it far more often than I used to, because the cost/benefit objection just crashed and burned. It makes sense all the time now, especially for small rooms, and especially for rooms that need high isolation.

Thanks very much for bringing this to me attention! It's VERY interesting. I love it when I'm wrong about something, and learn something new that corrects my opinion, but in a good way... It turns out I was a fan of GG on the low level, but now I'll be a fan on the high level, because I wasn't giving it enough credit!

- Stuart -
Old 1 week ago
  #15
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GreenGlue ... should have been called Green Goo.

There was 1 video posted on the Web that showed a demonstration that COULD have left an impression that GG had an 'adhesive' ability. It does NOT.

Glad to see SoundMan's response here. [He was also key to my build]

Personally, I find Avare to have a wonderful sense of humor. Not only the depth of his knowledge/experience ... but his UN-selfish sharing of that ... WITH SUPPORTED, Documentation. He provided me plenty of Research Data. Gervais is this way too. [I've several of his books].

When they express an 'opinion' ... they'll tell you that.

When we did our build, I had so many questions. Common sense is not always applicable with Acoustic design/treatment ... that is UNTIL you Re-Learn what is
happening.

2nd ... the amount of investment $$$ that goes into these builds can be very serious. The mentioned GURUS help guided to NOT waste $$$ and time. [yes, it is a level of trust ... heh ... its the Internet].

But when it was completed as to their guidelines, my Room would rival most any Top Control Room that I worked in over 3 decades. [it only cost me some voluntary DONATION to the JS Studio Design site ... which I was happy to do. Maybe you should visit that dedicated site.
Old 1 week ago
  #16
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Quote:
Originally Posted by RJHollins View Post
GreenGlue ... should have been called Green Goo.

There was 1 video posted on the Web that showed a demonstration that COULD have left an impression that GG had an 'adhesive' ability. It does NOT.

Glad to see SoundMan's response here. [He was also key to my build]

Personally, I find Avare to have a wonderful sense of humor. Not only the depth of his knowledge/experience ... but his UN-selfish sharing of that ... WITH SUPPORTED, Documentation. He provided me plenty of Research Data. Gervais is this way too. [I've several of his books].

When they express an 'opinion' ... they'll tell you that.

When we did our build, I had so many questions. Common sense is not always applicable with Acoustic design/treatment ... that is UNTIL you Re-Learn what is
happening.

2nd ... the amount of investment $$$ that goes into these builds can be very serious. The mentioned GURUS help guided to NOT waste $$$ and time. [yes, it is a level of trust ... heh ... its the Internet].

But when it was completed as to their guidelines, my Room would rival most any Top Control Room that I worked in over 3 decades. [it only cost me some voluntary DONATION to the JS Studio Design site ... which I was happy to do. Maybe you should visit that dedicated site.

Thank you RJ. I'm not building a control room or a proper studio. Im basically adding some mass to an existing ceiling in a very large room (1500 sq feet with 13 foot ceilings) and then building a complete shell room and a second ceiling below the existing ceiling. The space is going to be multi use for shows-both art and music..and some recording. I throw large parties/events that are community oriented-directed at and for the creative community in general. I also record demos for folks when i have the time.

The walls will have two layers of material-top layer of drywall, base layer of a mixture of drywall and either MDF or Plywood..the reason for the wood in the walls is so i can accommodate screws anywhere in the wall for visual art shows ..where installations are being displayed etc..

I have enough experience to know that what I'm doing, even without Green Glue and a lot of products that are available these days, will make a huge difference..

My budget is pretty tight right now and all that I'm looking for are a few ways to add a little bit of sound containment value here and there...

Hence, my questions about Green Glue..which i think are extremely reasonable questions. for a long time now, leading up to this build out, I've watched and read a ton of material on Green Glue and other products..and what I come away with is this..There are a LOT of gray areas with this product and similar products, many misunderstandings, definite 'unkowns'

..The application seems odd, haphazard and wasteful to me. If it's necessary to apply it like this..i want to know defintively 'why' and how this came to be the way to do it..pretty reasonable i think.

I never totally trust any old company's guidelines..if something feels funny or i don't understand 'why', i read about it..You should too..everyone should..i always want to know the logic behind the action because there are almost always options, sometimes better ones..

You never know, Green Glue could be replaced with synthetic Oatmeal someday..you never do know.

..When Soundman 2020 says the following..he is speaking to one of these gray areas because, as he says, he is speculating..

--"It is very necessary, actually, and very wise. If you were to lay it out in nice neat rows that never cross over each other, you'd be creating a pattern that could adversely affect how it works. I'm speculating here, but it occurs to me that a regular repeating pattern could cause the same type of issues that regular repeating patterns cause with diffusers..."__

Speculation can be an extremely important thing..it speaks to curiosity and asking questions about stuff..it's all that im doing in this thread.

Also, Soundman, as an experienced person in this field, was also very surprised to find that the quote I started this thread with, from Rod Gervais, was new information for him...I posted it because I had never heard this either,,,and I've done a lot of reading on Green Glue..

Asking questions is one of THE most powerful things..and when I get answers that feel dismissive and 'cut and dried' about a product..it almost always makes me ask more questions.

I know what dismissive IS and I am very careful to make people who ask questions feel good..feel great, about asking those questions..very destructive to crush that spirit in anyone.

..Soundman 2020 reinforced the value of this in certain recogntions he made here.. IMO..there are ALWAYS things, that even the experts, can learn.


I don't need this space to be perfect and acting like a pro studio and my budget does not allow for a lot of this stuff..My eye is on adding mass in some existing spots (existing ceiling) and adding a basic decoupled room within this room.
Old 1 week ago
  #17
We used GREEN GLUE when building my mastering studio. Phenomenal product when used with the supplied directions. I can't recommend it enough. We used two sheets of 5/8" plaster board, one running horizontally and one sheet running vertically. Sheets were 12 foot long to minimize seams. The nay sayers all seem to be promoting their own acoustical products. FWIW
Old 1 week ago
  #18
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Quote:
The space is going to be multi use for shows-both art and music..and some recording. I throw large parties/events that are community oriented-directed at and for the creative community in general. I also record demos for folks when i have the time.
That clarifies a lot! So your room is basically going to be a performance room, with secondary use as a live room. Knowing what the goal is makes it a lot easier to offer advice.

The normal process I follow with clients when they are just starting out, is getting them to define measurable, realistic numbers for their goals, to avoid guessing. One of the firsts numbers I want, is isolation: How much isolation do you need, measured in decibels of Transmission Loss? The next is: How low do you go? In other words, what's the lowest frequency, in Hz, that you need good isolation for? If you know those, then it's a lot easier to define what construction materials and what techniques you could use to get the isolation you need at the frequency you need it. There are research papers, equations, tables, charts, graphs, and other things that you can look at to see what materials and techniques are open to you to achieve that goal, then you can choose the one that best fits your budget, skill set, and local conditions.

Silly examples: if you say that you need to isolate a Grateful Dead impersonation band rehearsal in there, with all their gear, and that you have a nursery for newborn babies on the other side of the wall... well, that's one extreme. But if your worst case is a singe piccolo player practicing scales, and the building is located in the middle of the desert... that's quite a different scenario.

So, I'd suggest that, instead of looking at materials and comments on those materials to decide if you'd like to use that, rather you should start by defining your numbers. Define "How many dB of TL do I need?". And define "What is the lowest frequency I need to isolate?". Based on that, we can help you find proven systems and methods that will produce what you want. They might of might not include Green Glue, depending on your numbers. For typical performance spaces / rehearsal spaces in typical locations, there's probably going to be at least half a dozen possible ways of getting what you want, and by asking more questions we can help you narrow that down some more.

That's the way I approach studio design. Even though your place isn0t really a studio, the same process still works. That's pretty much what we did with RJ )Hi there RJ! Good to see you over here! )

- Stuart -
Old 1 week ago
  #19
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Quote:
Originally Posted by Pchicago View Post
This is one reason why I'm a bit skeptical about the recommended application technique..it's the crossing over of the beads..which seems very unnecessary to me, not wise, even. Understanding of course that GG is a bit soupy..it still will happen..again, very tough to torque a drywall screw to compress a product like this between two large sheets..without tearing.
We found it much easier to trowel the GG on the sheets then loading/using the dispensing gun with 5gal buckets. I contacted my supplier about it and this was the response I got-

It's really all about getting from point A to point B withe correct ounces per square foot. The bead won't really matter because it will all lay flat to 1/32" of an inch anyway. Some people online will say it matters, but it doesn't. They refer to a test that shows a 1 STC difference between dispensing and troweling. That's within the margin of variables seen from test to test on different days, different labs, different equipment, etc.

From what I understand quietrock has the viscoelastic layer with complete coverage- and what is inside there is essentially GG but purple...

I also felt that it depends a bit on if you are doing 2 tubes worth or 3 per sheet. 3 is A LOT. I found it hard not to have the beads going over each other multiple times and hand similar concerns (especially with studs/joists 24 oc and nothing to tighten it between). With ~3 tubes you can completely cover a sheet when troweling it on. I also felt that it was getting into some pretty thick in some spots with the dispenser and a lot more time consuming that way.

In terms of jobsite cost, my 3 man framing/drywall crew cost about the same as 40 gal of gg per week (in 5 gal buckets). When I saw how slow it was going with the dispensing gun, it made more sense to me to have one guy trowel it (gloved up) and the other two hanging and just err on the side of using a little more than 3 tubes per sheet. Messier, but way faster.
Old 6 days ago
  #20
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Quote:
From what I understand quietrock has the viscoelastic layer with complete coverage- and what is inside there is essentially GG but purple...
What's inside "quietrock" is not Green Glue, and not the same. It's called Quietglue...

Quietglue is nothing at all like Green Glue (despite the claims and hype). There's actually a very interesting video where some guys building a studio tried out both (among other strange things....) and ended up with a goopy mess from using Quietglue, while GG worked just fine, as advertised.

YouTube

Worth watching. I don't agree with some of their conclusions, but they did get good results with GG, and the results they got with Quietglue are fascinating. The video is long (about 20 minutes) but skip to the 17:30 mark for the direct comparison of the same application of both... It's not the first time I've heard of folks who used Quietglue getting that type of result...

So it's not the same. Not comparable.
Old 6 days ago
  #21
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Quote:
Originally Posted by Soundman2020 View Post
What's inside "quietrock" is not Green Glue, and not the same. It's called Quietglue...
Interesting-

I just know that I've taken apart a piece of quiet rock and the quiet glue, as best as I could see from the 6"x12" piece I had, was continuous between the two sheets. Maybe not a good comparison though as it is a different product.
Old 6 days ago
  #22
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My experience with the green goo has been positive, granted I used like 30 gallons, over the course of two walls, and dozens of sheets of drywall,
but the TL from the outside environment has been [email protected] least 75 db loss in both directions.

YYMV

Light

Temple
Old 2 days ago
  #23
Gear Addict
 

I am not sure I agree with Andre on this one. It is often not possible to reasonably compare tests done in different acoustic laboratories at different times.

I am aware of a test at a full size acoustic test lab (10m^2 test wall, 200m^3 rooms). The wall was:

* Light-gauge steel stud frame, lined one side only with plasterboard.
* Plasterboard was 2x layers 13mm thick
* Wall was tested with and without Green Glue (3 tubes per sheet of plasterboard). Glued sheets were allowed to cure for a few days prior to installation. Dozens of bags of sand were placed on the plasterboard sheets to compress the Green Glue.

The Green Glue did a great job of damping the coincidence dip but not much more. It was a pity the Builder did not try a double stud frame test but he had limited time and figured any low frequency damping benefit would show up in a single-sided test.
Old 2 days ago
  #24
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Quote:
Originally Posted by Sebg View Post
I am not sure I agree with Andre on this one. It is often not possible to reasonably compare tests done in different acoustic laboratories at different times.

I am aware of a test at a full size acoustic test lab (10m^2 test wall, 200m^3 rooms). The wall was:

* Light-gauge steel stud frame, lined one side only with plasterboard.
* Plasterboard was 2x layers 13mm thick
* Wall was tested with and without Green Glue (3 tubes per sheet of plasterboard). Glued sheets were allowed to cure for a few days prior to installation. Dozens of bags of sand were placed on the plasterboard sheets to compress the Green Glue.

The Green Glue did a great job of damping the coincidence dip but not much more. It was a pity the Builder did not try a double stud frame test but he had limited time and figured any low frequency damping benefit would show up in a single-sided test.
I hope this is some kind of a joke. Three day (guess) curing time? Green Glue requires a 30 day curing time. This was confirmed by Eric Desart.

Andre
Old 2 days ago
  #25
Gear Maniac
 

In addition to the totall inadequate curing time that Andre pointed out, there's these other issues:

Quote:
Dozens of bags of sand were placed on the plasterboard sheets to compress the Green Glue.
WHY???!!! Did they not read the instructions?

Quote:
Glued sheets were allowed to cure for a few days prior to installation.
Ditto.

If thy didn't follow the manufacturers instructions in three different critical ways, I'm not surprised they didn't get the results. It seems like they set out to deliberately sabotage the test, by doing as much as possible wrong.

Quote:
I am aware of a test at a full size acoustic test lab...
Not much of an acoustic test lab if they don't follow the manufacturer's directions for installation of the product under test...

Quote:
* Light-gauge steel stud frame, lined one side only with plasterboard.
* Plasterboard was 2x layers 13mm thick
So what was the OTHER side of the wall made from? That's only one side.... What insulation was used in the wall cavity? How deep was the cavity? How thick was the insulation? What was the stud spacing?

Way too many unknowns here for this to be any use to anyone. Plus, not even following the manufacturer's instructions, makes the test rather invalid, and pretty useless.
Old 13 hours ago
  #26
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Acoustic labs are usually just paid to carry out tests, the client builds the wall however they wish.

In this case, it was 2010. The client was a builder that had a few things he wanted to investigate. I suppose he figured if he was going to get an effect it would show up after a few days - law of diminishing returns (e.g. get 50% effect after a week, 80% after 2 weeks, 100% after 4 weeks).

The wall frame was lined one side only. The Builder expected that if there was a benefit to be had at low frequency, it would show up. It didn't, so he moved on.

Doesn't mean he wouldn't revisit the situation again in the future.

When I had a look at the sheets they had a satisfying "thunk" when thumped and it certainly appeared the Green Glue had been squished to about 0.5mm.

But my point stands that a true A-B test should be a comparison with/without the product in a back-to-back test - same lab, same batch of materials etc. I am not sure that this product has been tested in this way in a double-stud wall.
Old 44 minutes ago
  #27
Gear Maniac
 

Quote:
the client builds the wall however they wish.
... silly client! To pay all that money to get acoustic testing done in a proper lab, then do an invalid test! You would think that, if somebody was going to go to all the time and expense of testing an isolation wall in a lab for many days, they would at least do it right, and follow the manufacturers' instructions! Doing it so badly wrong, totally invalidates the test: he didn't actually test anything meaningfully.

All that he demonstrated is that when you build a wall wrong, it doesn't work very well. I think most people knew that already...

But hey, it's his money! If he wants to throw it away like that, I guess he's entitled to do so! But then he should refrain from releasing his invalid results in public.

Quote:
The Builder expected that if there was a benefit to be had at low frequency, it would show up. It didn't, so he moved on.
In other words, he started with invalid assumptions, then built the wall wrong anyway, and proved nothing at all...

Quote:
it certainly appeared the Green Glue had been squished to about 0.5mm.
That's a BIG question: Why would he even want to do that? What was the point of clamping (or heavily loading) the wall to "squish" the Green Glue, when the manufacturer gives no such instructions, and anyone with basic understanding of how CLD works would tell you not to do that? Why would he even do that? It makes no sense... Perhaps the automotive equivalent would be deciding to test if your fuel economy and car handling improves by letting half the air out of your tires, running them basically flat: anybody who understands tires would tell you in advance how silly the test was, and could predict the outcome...

I guess the moral of the story is: never trust a builder to do the job of an acoustician...

Quote:
But my point stands that a true A-B test should be a comparison with/without the product in a back-to-back test - same lab, same batch of materials etc. I am not sure that this product has been tested in this way in a double-stud wall.
I'm pretty sure it has! Numerous times. All you have to do is look over the Green Glue website to find numerous examples of that: many tests in many configurations performed in independent acoustic test labs... but performed according to the manufacturer's instructions, and performed by acousticians who know what they are doing, not by builders who don't have much of a clue.
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