Recording - October 2010 - 34

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STUDIO

Green Glue
By Brian Gadson with Robert Ishida

Funny Name, Serious Noise Barrier
When Recording’s editor asked me about the new substance called Green Glue, and asked if I could share reallife stories of jobs involving sound control, I ran down a list in my mind, from clients with loudly snoring family members to a studio with a neighbor’s barking dogs (a job where I did a spectral analysis and devised a system of construction materials that kept the bark’s frequency range outside...). The problem area Shaggy dog stories aside: In general, the most difficult and costly frequencies to address have always been those in the area of 125 Hz and below, which coincidently happens to be, in our musical world, the power behind most of our music and special effects. Cut off everything below 125 Hz in your mix and see what you have left. Unfortunately, 125 Hz is where the all-powerful, yet imperfect and archaic STC (sound transmission class) rating stops. How convenient for the manufacturers! Don’t get me started on this subject. [See www.stcratings.com and www.greengluecompany.com/understandingSTC.php for more on STC.—Ed.] Realistic expectations When clients call and mention “soundproofing” I quickly suggest we’d better talk in terms of sound control, noise control, or noise abatement—all valid terms that don’t come with the baggage of unrealistic expectations that “soundproofing” carries with it. Sure, that word is being used by makers and sellers of many such products, but don’t you feel better knowing that we are discussing a goal that is achievable? Materials old and new The best ally the studio builder has had for low frequencies of 250 Hz and below, short of inner-wall and massive thick space-consuming construction, has been 5/8" layers of drywall in conjunction with layers of loaded vinyl or lead sheeting products. Loaded vinyl and lead sheeting products are very expensive for the project studio builder on a budget. Now there is help and hope in the form of a product called Green Glue. Yes, it really is called Green Glue. It comes in caulking tubes for a gun, and in bulk, in 5-gallon buckets if you are a contractor doing some volume work. This viscoelastic material (meaning it doesn’t harden or dry
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out) has some amazing lowfrequency damping properties, as well as being able to affect the rest of the frequency range. When applied correctly, and let me say that again, correctly, between layers of drywall, it can give you a huge reduction in lowfrequency transmission. And if you have the budget and can also throw in a layer of loaded vinyl, you are really getting considerable reduction without building threefoot thick walls that would reduce the size of most project studios by twenty percent! Less pricey, better in some ways By the time you factor in labor and materials, a wall which consists of two layers of 5/8" drywall with Green Glue in between is no more than half the price of a loaded vinyl wall of the same composition, and better in some parts of the frequency spectrum. It is also much faster, cheaper and easier to install if you are trying to do the work yourself. Green Glue at roughly $15.00/tube, with 2 tubes per 4 x 8 sheet of drywall, works out to be about $0.94/square foot. Loaded vinyl can be $3.00/square foot. I was introduced to Green Glue by my Drywall Contractor and friend Robert Ishida whose company specializes in sound-reduction product installation in Los Angeles. I always involve Robert in all my studio construction situations where this kind of knowledge and craftsmanship is needed. When I asked Robert to contribute information regarding how Green Glue helped in his field of expertise, this is how he responded. The main result we get from using Green Glue is the effective damping of low-frequency sounds through the dispersal within mass barriers (i.e., double layers of 5/8" or 5/8"+vinyl). On its own, Green Glue provides a 10 STC lower than double drywall by itself. Vinyl with Green Glue gives us 26 lower STC. When taking into consideration the cost of vinyl or #2 lead sheeting

http://www.stcratings.com http://www.greengluecompany.com/understandingSTC.php

Recording - October 2010

Table of Contents for the Digital Edition of Recording - October 2010