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Author Topic: Layering glass  (Read 9008 times)

whatismisophonia

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Layering glass
« on: April 12, 2012, 11:45:21 AM »

So I was looking over some acoustic testing on glass from the NRCC (that Canadian place), where they found that a thin oil film between two layers of glass helped with the resonance/coicidence dips a little, as opposed to nothing in between two layers simply placed against each other.  Seeing as how laminated windows cost out the ass, I was wondering if an oil coat was feasibe in real life application, or perhaps a window film application solution?  And what about layering acrylic onto glass, since acrylic resonantes differently?  As a side note, I can almost gaurantee that the damping glue companies are working feverishly on a replacement for pvb in laminated windows; it'll be nice when they finally come out with a double stick sound-damping window film or something.

johnbergstromslc

  • Guest
Re: Layering glass
« Reply #1 on: April 12, 2012, 10:45:48 PM »

Now you're talking about oil in between glass layers????

To answer your question, no, it's not one bit feasible.  It would be a complete nightmare to just construct an assembly like that...

And to answer your other question, no, 'damping glue companies' are NOT feverishly working on a replacement for PVB, because there isn't a good one.  There's a reason that PVB has been used to laminate glass for 75+ years - it sticks to glass the best. 

You're not going to get exceptional performance from a single piece of glass (of reasonable thickness), laminated or otherwise. 

whatismisophonia

  • Guest
Re: Layering glass
« Reply #2 on: April 13, 2012, 05:49:21 AM »

It would be a complete nightmare to just construct an assembly like that...

Well it you havent tryed, how the hell do you know?  In putting it together, just off the top of my head I can think of several uncomplicate ways to construct it without air bubbles, I'm just curious as to what kinds of issues might come about later on down the road; but I guess nevermind. 

And as far as a replacement for pvb goes, they WOULD be working on one precisely because there ISNT currently one.  People who are set in their ways like to think that technology doesnt evolve.  I still can't figure out why.  I swear to Jesus, the saints, Budda, Krsna, and Zeus himself that in the near future you will find Quietwindow laminate, or something like that; windows are the only thing they haven't got anything for, and it would be a huge market.  Of course theyre working on it if theyre smart.

As for your final comment, I am aware of that.  I was talking about the one issue here, that of the individual panes in a complete system (with air gap).  And glass is a dense heavy material if its thicker, at least, than 1/8 inch, and no worse than any other building material.  All the lab testing + individual personal experience reviews (I've checked around, not just on the quietglue and greenglue websites) vouche for damping glues;  I can't figure out why you guys give damping so little credit.  Actually, I have a theory, but I won't say it.  :-X

Randy S

  • Senior Soundproofing Technical Specialist
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    • Super Soundproofing Co
Re: Layering glass
« Reply #3 on: April 13, 2012, 04:46:24 PM »

Im not going to chime in on the window conversation (Im not a window expert) but I will comment on the green glue dampening compound product...

We love Green Glue and sell quite a large volume of it... And it does work in the right applications...but it is NOT the magic fix all and Never will be...period... and if you havent used it  and experienced the results in the field than you have NO idea!! even the difference from a 2 tube to a 3 tube formula.... I know, Ive seen the results First hand...
Randy Sieg

Super Soundproofing Co
www.soundproofing.org
888-942-7723
Ph. 760-752-3030
Fax.760-752-3040

johnbergstromslc

  • Guest
Re: Layering glass
« Reply #4 on: April 13, 2012, 10:36:48 PM »

Well it you havent tryed, how the hell do you know?  In putting it together, just off the top of my head I can think of several uncomplicate ways to construct it without air bubbles, I'm just curious as to what kinds of issues might come about later on down the road; but I guess nevermind. 

You are exactly right - I haven't tried it.  That's because I'm knowledgeable and experienced enough to not waste time trying to come up with concepts that won't work any better than a product that's already out there (designed by engineers and PhD's), readily available and effective.

Here's an idea:  Why don't you try it?

If it turns out to be a big waste of time and money, then I am right, and maybe you are cured of some of your idealism in this field. 

If you can come up with a solution that is better than regular old laminated, with a PVB interlayer, then you are right (and maybe rich...)

Good luck.

houseon

  • Guest
Re: Layering glass
« Reply #5 on: April 15, 2012, 02:45:01 AM »

HI! So Maybe this will lighten up this thread...Can someone tell me if the basic idea of adding another single pane window into the frame of an existing window would provide me with decent enough sound blockage compared to buying windows from 'soundproofwindows'.com? 

I've been reading this forum and trying to figure things out and currently live in a 1951 house with single pain windows and annoying neighbors.  So Pay $3600 to have soundproof windows installed in my bedroom - 4 windows OR get a contractor to install 4 basic windows over the original windows for $1000 or so - any ideas?

What about Climatizers   http://www.climatizerwindows.com/faqs.htm -

do you think these are half-way decent?  They are about 1/2 the price of the 'soundproofwindows.com'

Your exptertise would be greatly appreciated!!!

Thanks!

johnbergstromslc

  • Guest
Re: Layering glass
« Reply #6 on: April 16, 2012, 11:10:30 PM »

HI! So Maybe this will lighten up this thread...Can someone tell me if the basic idea of adding another single pane window into the frame of an existing window would provide me with decent enough sound blockage compared to buying windows from 'soundproofwindows'.com? 

I've been reading this forum and trying to figure things out and currently live in a 1951 house with single pain windows and annoying neighbors.  So Pay $3600 to have soundproof windows installed in my bedroom - 4 windows OR get a contractor to install 4 basic windows over the original windows for $1000 or so - any ideas?

What about Climatizers   http://www.climatizerwindows.com/faqs.htm -

do you think these are half-way decent?  They are about 1/2 the price of the 'soundproofwindows.com'

Your exptertise would be greatly appreciated!!!

Thanks!

I would recommend installing windows with 2 glass panes separated by a layer of oil.... ha ha...

Another single pane of glass will help a lot, if you get a big as possible airspace and it is sealed well.  But you will have condensation problems in the winter.  You can compensate with silica gel between the panes, but you probably don't want the bother. 

I would recommend getting regular replacement windows with custom glass.  A 'normal' double glazed window is SS+SS (single-strength over single-strength).  The panes of glass are 2.5 mm thick and rate an STC in the low 30's.  You can go with double-strength (3.0 mm) or thicker for better sound reduction.  Also, you want to have different thicknesses of glass to minimize resonance.

You'll have to price out the options, but I would recommend getting 1/4" over 3/16", and try to make sure the 1/4" pane is the outside pane, where it will do the most good.  If your contractor tries to tell you he can't get custom IGU's, dump him!  He's just being lazy

Another advantage is that you can get low-e and maybe argon filled, if it's not too pricey.  You will reduce the neighbors noise, save money on heating/cooling and be more comfortable.

Oh, yeah, avoid Soundproof windows like the plague.  All you have to do is peruse the posts on this site to see how much they rip people off...

Not sure what Climatizers are, but even half the price of Soundproof windows is too much.

Shoot another post or email me if you have any questions.   

 

whatismisophonia

  • Guest
Re: Layering glass
« Reply #7 on: April 17, 2012, 05:31:56 PM »

Glass has big resonating problems.  Damping helps with resonating; ergo, damping for glass = good.  I'm not trying to replace pvb because I don't care about making a shatter-proof window.  We're talking about damping here, nothing else.  As such, I'm having difficulty wondering why a thin film of something between two panes of glass that would help with damping besides pvb would be such an outragious notion, or "idealic"; the oil was just an idea because the NRCC actually took the time and expence to test it.  I'm not crazy or idealic; I'm honestly trying to be sensible.  If the oil or whatever doesn't break down or turn yellow in the presence of uv light, is not damaged or hardened by a little cold weather, and is clear enough for light to shine through well enough, and is easy enough to implement, I fail to see the problem.  If nothing else, the added weight for minimal cost would add to the soundproofing, not to mention the fact that it wouldnt resonate like the glass.  As a side note, I think that the NRCC was also tossing this idea around because separating solid layers with oil might be helpful for heat retention during cold canadian winters.  There is also the fact that the oil would not freeze, allowing it to continue working as a damping agent.

At any rate, I do intend to try; I was just curious if anyone here who is interested in soundproofing had at least bothered to experiment.  I have a single paned window on the outside of my wall.  I have attached a layer of 1/8 inch acrylic to the interior of the wall with 3 or so inches of airgap. 
Because acrylic is so light, I know that I should attach more layers to it, and so I shall.  What I want to do is remove the current acrylic layer, buy another one, and adhere the two together with thin strips of durlar plastic around the perimeter that would separate the two panes, thus allowing a very thin gap in the middle.  I would have an opening at one corner with a sort of makeshif funnel where I would slowly poor in the "substance".  I would then attach this unit to a wooden frame which would be mounted on the interior wall opening.  I'd have a larger airgap and a thicker heavier setup at the very least.  Right now I'm more than a little tight on cash (do not have a job currently), but eventually I'd like to do this and report back.  That is all.   

johnbergstromslc

  • Guest
Re: Layering glass
« Reply #8 on: April 17, 2012, 10:34:59 PM »

I'm not crazy or idealic; I'm honestly trying to be sensible.  If the oil or whatever doesn't break down or turn yellow in the presence of uv light, is not damaged or hardened by a little cold weather, and is clear enough for light to shine through well enough, and is easy enough to implement, I fail to see the problem. 

Well, we will have to wait for the results of your experiment...

You'll see firsthand if using an oil-membraned glass assembly is at all sensible in a practical, residential application. 

whatismisophonia

  • Guest
Re: Layering glass
« Reply #9 on: August 28, 2012, 04:35:19 AM »

Figured I'd update this thing since I now have something to report for those who may be interested.  I went on ahead and got some cheap 1x4 lumber and created a rough window frame out of it such that the widths are attached together similar to wall framing.  Before I did this though, I had to rabbit out around the interior of the boards in order to make a continuous slot for the acrylic panel to slide into.  I made the rabbit so that it would be about 3/8" in from one side of the frame, and 3 1/8" in from the other side;  the deeper 3 1/8" side would seal against the window trim on my current wall so that the extra few inches would be added to the total space between the current single paned window and the new acrylic panel, giving me a total of almost 8" between the exterior glass window (little more than a storm window which sets directly on the outside of the sheathing) and the interior acrylic window.  The acrylic panel that I slid into the rabbits is actually composed of two individual 1/8" panels which are separated from each other by 1/16" or so.  The gap is created by 1/32" x 1/2" strips of plastic that are inlayed and glued around the edges of the panels (the glue on either side of the plastic brings the gap up to the 1/16" measurement).  The completed whole panel is then slide into the rabbits and the frame attached to the wall; I attached it at the top with hinges, installed a latch at the bottom, and sealed the gap between the frame and the original wall window trim with plastic weather stripping which is attached to the frame. 

So yada yada, long story short, I originally had a single 1/8" acrylic panel attached directly to the window jambs beneath the trim; I've removed that panel, doubled its thickness, and doubled the air gap by attaching it to a self-made interior awning frame work.  I intended to eventually fill the 1/16" gap between the two panels with oil, however I wanted to observe the effects of the doubled mass + doubled air space between the two window assemblies without the oil first.  The result is that I hear only the loudest of engines, and the sound coming through the window is almost equal to the sound coming through my wall (3/8" wood siding, 3/8" osb, 3.5" fiber filled air gap, 3/8" gypsum board). 

I did eventually try to fill the thin gap with oil, but even given the light weight of the oil and the small amount that I needed to add, the acrylic was more than flexible enough to bulge out to about a 1/2" gap close to the base of the panels.  I attached some 3/8" strips of wood to the front and back panels to keep them from bulging out so much, though this still wasn't good enough.  I then laid the frame flat on the ground and pressed the excess oil from the opening which I had poured the oil in through so that there was only the thinnest film of oil in the middle.  I sealed the thing up and reattached it to the wall, though excess oil is still settled toward the bottom, causing it to bulge out a little, and causing light to distort as it shown through it.  The window is 32" x 44" and the amount of oil I used was roughly 20 floz (600 ml).  I need to add more support to the panes, and the oil did start leaking out, though I knew my sealing job was crap because the glue skinned over too quickly and I couldn't get it to come out in a continuous bead like if I were using caulking; I was just hoping it would barely be good enough, which it wasn't.  I'd like to get some specific glue that is actually made to wield two pieces of acrylic together, and reseal the edges, though I haven't done this yet.  It's used often in the construction of acrylic fish tanks.         

whatismisophonia

  • Guest
Re: Layering glass
« Reply #10 on: August 28, 2012, 04:41:37 AM »

There are two positive results of the oil film:

1. Whether from the extra weight or any damping effect of the oil, the transmission loss was definitely noticeable over no oil at all.  Even if it were from extra weight, it would still be worth the money, as the oil was much cheaper than a third layer of acrylic.  My sealing issues were mostly a result of terrible application of glue (not sure why they don't sell that crap with an applicator tip), though a bit more research would have helped as well.

2. Two panes of material next to each other or with even a thin air gap will result in obscured light penetration.  I found that by introducing a thin oil film that the two layers became see through as though they were one.  If a guy had old fashioned windows with small individual panes and wanted to keep the window and upgrade the panes at minimal cost, he could remove his existing panes, buy some extra 1/8" panes, laminate them over his existing ones, and reattach them (even if he didn't have damping in mind). 

As for my soundproofing efforts, I intend to rip out the wall, add 2'' of staggered studs, add 5/8" drywall, and reattach the acrylic window, which will then have a 10" air gap.  I'd also like to frame in some thin 2" x 2" boards over the original window framing before I attach the wallboard and only have these boards attached to the added staggered studs with a small space between the new and old framing, such that the exterior and interior windows will be decoupled, and the framing only attached at the stud sill plates.  Not sure if that's within code, but wtf I'm outside of city limits and it wouldn't hurt anything anyway; considering that the splits in the finished window jambs to keep the windows decoupled are pumped full of acoustic caulk.  Also, the cost for all of the acrylic in my interior window is $50, just fyi.

whatismisophonia

  • Guest
Re: Layering glass
« Reply #11 on: October 12, 2012, 07:13:34 PM »

I’m posting pics from the NRC files in question.  The concept of layering glass with oil between layers was not intended to test damping, however it seems that the test data is showing something more going on than simply deleting the tiny air pocket.  As the last graph (which is from a different file) shows, the coincidence dip lowers in frequency with increasing thicknesses of glass, however, the first two graphs comparing oiled and non-oiled layered glass show an even increase in TL across all frequencies in the oiled layered panes compared to the single pane.  Now, the coincidence dip in the oiled panes may be more severe than in the non-oiled layered panes, however this coincidence is not lower in FREQUENCY than that of the single pane assembly.  This and the statement made about laminated glass in the second file pertaining to the last graph lead me to believe that the oil is not only removing the resonance by filling the air pocket, but is also creating a damping function by allowing the panes to vibrate somewhat independently of (and against) each other, which would account for the increase in TL without apparent change in frequency as I would expect if I were comparing it to solid 6mm glass.  This hypothesis is also supported by a later statement in their second file referring to the benefits of laminated glass.  Here are the statements pertaining to graphs one and two:

"In evaluating the effect of interpane spacing on TL it seemed desirable to establish the performance with zero spacing, as a reference case.  Figure 12 presents the data for single 3-mm glazing and two layers of 3-mm glass nominally in direct contact.  The change in TL is very similar to that reported elsewhere for gypsum board partitions, with three obvious features: (1) the coincidence dip at 4 kHz remains clearly defined, indicating that the two layers are not acting as a single layer of 6-mm glass; (2) for most frequencies the TL of the double layer is 5 or  dB higher, as one would expect because of the increased mass; (3) around 2 kHz the increase in TL is much smaller."

"Two simple hypotheses may be advanced to explain the smaller increase near 2 kHz:  one or more of the three windows may have sufficient contact between layers to make it act like a single layer of 6-mm glass (with fc~2kHz). Alternatively, there may be a small air gap between the panes; the resonance frequency of 2 kHz would occur for an airspace ~0.4mm (which could readily exist, considering the observed presence of minute glass chips). To investigate these possibilities further, an additional test was run with a very thin film of oil between the two layers of glass; the data are included in Fig. 12.  The resulting TL curve matches very closely the shape of that for a single layer of 3-mm glass, but it is higher by an average of 5.4 dB (with a standard deviation of 0.9 dB).  Because the oil would both reduce interpane friction and move in the mass-spring-mass resonance to much higher frequencies, this test does not discriminate between the two hypotheses about the origin of the dip at 2 kHz.  On the other hand, it does give a result that can reasonably be interpreted as the TL of double glazing in the limit as interpane spacing goes to zero."


whatismisophonia

  • Guest
Re: Layering glass
« Reply #12 on: October 12, 2012, 07:25:23 PM »

Here are the statements regarding the last graph included:

"At lower frequencies the measured TL is higher than the mass law prediction; this occurs because of edge constraints and the size of the window relative to the wavelength of sound waves. These effects are generally insignificant for large surfaces such as the walls separating rooms, but they increase the TL for small panels such as typical windows. How much the TL is increased depends both on the size and shape of the window and on how the glass is mounted in the frame. using soft resilient seals (such as neoprene gaskets) can increase the low frequency TL by several dB."

"At higher frequencies, the measured TL drops far below the mass law prediction. This sharp decrease in the measured TL is commonly called the "coincidence dip".1 It is caused by bending waves in the glass panel. The frequency at which this occurs is inversely proportional to the thickness of the glass. For 2 mm thick glass, the coincidence dip would be near 5 kHz. For 18 mm glass, the coincidence frequency is in the 500 Hz band, as shown in Figure 1. Near 500 Hz, the TL for 18 mm glass is actually lower than that for 4 mm glass. For frequencies above 200 Hz, the measured TL for 18 mm glass is far below the performance predicted by mass law. Because of this effect, the STC rating for single glazing increases very little with increasing glass thickness."

"Above the coincidence frequency, laminated glass (consisting of two or more layers of glass bonded together by thin plastic interlayers) can provide much higher TL than solid glass. Laminated glass may closely approach mass law performance above the coincidence frequency. This improvement is apparently due to damping (dissipation of vibrational energy) by the plastic interlayers. It should be noted, however, that damping is normally temperature dependent.5 At typical Canadian winter temperatures, the increase in TL due to glass lamination may be drastically reduced."