Since I'm still planning my HT build, I've been performing extensive research on various topics, and I happened to dig up this thread.
Getting past the mud flinging and since I don't have an emotional attachment to Green Glue or any other similar products, let me say that I actually read the reports that Ben cited.
First, they were performed by the same lab, same tester, on the same day. The conditions and pre-conditions for both tests as reported are identical. And guess what? The results of the 2011 tests are very similar. That is, both products performed comparable to one another. I don't view this as saying "Product X is as good as Green Glue," rather I'm saying based on this information both products appear to perform a similar function in a relatively equal manner. In fact, I'd say that to claim one or the other product is superior - based on these test results alone - is splitting hairs.
Read on and I'll underscore my point based on summarizing the reports and compare the 2011 GG lab test to the 2005 GG lab test that is referenced on the Sound Proofing Company's website.
Now, I know there is some question as to performance over time, but realistically who has a clue about that in terms of objectively measuring it? It's just going to remain an unknown for both products unless someone wants to pay a lab to make a realistic HT environment for both and beat them to death over time. The fact is the lab did cure both products for 35 days prior to conducting the 2011 tests. That's as good as we're going to get for objective scenarios.
Originally Posted by Ben Shafer
Originally Posted by Ted White
In the field we are not walking on panels to compress the damping compound. We don’t have heavy bladder presses. We have little drywall screws holding a paper-wrapped product (drywall), and not all that many of them.
In 2005 we assembled walls, securing with screws to studs, then removed the screws to view glue compression.
I wish I could let this slide, however despite specific comments to the contrary, all of the tests panels were methodically walked on. This was significant enough of an issue to the lab that it was specifically detailed in the formal lab test reports.
Just wanted to clearly explain the truth about panel compression and laboratory test results.
I did a little reading through the Orfield Laboratory test reports listed on The Soundproofing Company website for Green Glue and there are three different tests (OL06-0942, OL06-0920, OL07-0530b) completed by the Green Glue Company where it specifically states in the panel description that "the sandwich was thoroughly compressed by methodically walking over the entire face."
Ben, with respect to the reports you cited that is true. The lab reports for those particular GG tests
that you referenced indicate those panels were walked on. However, I don't believe this is a relevant comparison here. The GG tests you referenced were metal stud walls and we all know that sound attenuation is different in metal vs. wood studded walls. Considering the fact that 99.9% of HT rooms will be built using wood studs, I don't believe those tests you pointed out matter to 99.9% of people in this forum. To your point that GG's tests also used that method in some of their tests, point taken.
Not trying to sound like I'm putting you down, but rather trying to clarify the points here.
Which tests should you have compared? We need to find the equivalent Green Glue tests to compare to your QG Pro tests. Per the SoundProofingCompany website, the equivalent is OL 05-1035.
Let's talk about this test, which Audio Alloy, Inc. paid for
. The test was conducted substantially earlier, on October 15, 2005. Unfortunately, this test report is not as detailed as the 2011 tests paid for by Serious Materials, but let's see what we have here:
1. The 2005 tests used the same ASTM test references: ASTM E90 and ASTM 413
2. The test wall was composed of 2 layers of 5/8" drywall on one side and 2 layers of 5/8" drywall on the other, with 116 oz. of Green Glue in between each of the drywall sandwiches. That is (if I recall correctly) 6 oz. less acoustic sealant vs. the 2011 tests, but it's close.
3. Environmentally, the humidity in the 2005 test was 5% higher
4. The source room and receiving room sizes are identical between all 3 tests (2005 and both 2011 tests)
Let's compare the Green Glue test results in 2005 vs. 2011.
The great thing about these two GG tests is the materials used have the same description. Not only that, but the total weight between the two tests spaced 5 1/2 years apart is a variation of only 0.3 lbs. (644.6 vs. 644.9 lbs.)! Overall surface density is 9.99 vs. 10.00 lbs. per sq foot. How convenient!
Unfortunately, we don't know if the GG was applied exactly the same way or not, but IMHO that's a good thing. Other than following instructions, how do we know any two people will apply it exactly the same? (not like application is rocket science, but still a valid point)
Let's compare the results and see how they stack up to one another.
Green Glue testing 2005 vs. 2011 (same Orfield lab - yes same address)
Hertz | 2005 TL | 2011 TL
80 | 23 | 22
100 | 26 | 24
125 | 35 | 37
160 | 41 | 41
200 | 40 | 43
250 | 45 | 43
315 | 47 | 45
400 | 50 | 47
500 | 53 | 51
630 | 55 | 52
800 | 57 | 53
1000 | 58 | 55
1250 | 57 | 56
1600 | 59 | 57
2000 | 58 | 54
2500 | 62 | 56
3150 | 67 | 61
4000 | 70 | 67
5000 | 70 | 72
Of course, nearly all are not identical but they are all very close except for the 2500hz reading. Anyone with a layman's understanding of lab tests (like me) knows a slight variation is normal.
Now, back to the GG vs. QG Pro tests that Serious Materials, Inc. paid for in 2011.
I'd say this entire discussion is useful in the sense that it appears to establish QG Pro as an acceptable alternative to GG, without respect to any particular person's preferences for any other reason. It would be interesting if the makers of GG would pay for similar tests on their dime, though I don't see they have any reason to do this unless they strongly believe the 2011 tests were flawed or staged. If it were my dime, I wouldn't bother unless the chemical composition of GG has changed in the past 10 years.
Comparing sound attenuation between either product is quite frankly so close to the point that unless you are REALLY picky about getting the absolute best absorption, I don't see that it matters which you choose unless you are concerned about a very specific, tight frequency range.
I'll compare the two just based on the 1st chart (2011 tests) which shows TL for 19 different frequency ranges from 80hz to 5khz. Of those, GG "wins" 8 times and QG Pro "wins" 7 times, where "winning"= superior performance. However, we are talking about differences of 1 or 2 TL in most cases. Hardly worth mentioning.
If you look at the STC curves for both products, their average is identical (53). The curves are very similar in appearance.
From 100hz to 250hz, GG has SLIGHTLY better performance (1-2 TL per freq level). However, QG Pro has SLIGHTLY better performance (1-3 TL) on the high end (2khz - 5khz).
Therefore, as I mentioned... if you are REALLY picky, you might choose GG based on these lab tests if you are most concerned with LFE. You might choose QG Pro based on a priority of attenuating high frequencies.
My point.... I don't believe someone can go wrong with choosing either product. A person's decision should be more along the lines of whether or not they want to use a damping compound period, cost, availability, etc. etc. From a lab testing perspective, they both seem like fine, suitable products to me.
If anyone can make a logical objection to my points, please speak up (unless you haven't taken the time to read the reports as I have, in which case please don't comment out of ignorance).