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 Post subject: Glue leaf layers
PostPosted: Fri Jun 11, 2021 8:03 pm 
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dont know if this is more theory than practice, but I remeber reading somewhere that it is bad to glue (in example your gypsum wall) double layers in leaf together.

This question actually came up when I was thinking options for my windows;
I noticed that you could actually buy PVB-foil and make your own laminated window
and as a brain teaser that got me thinking that one could layer up multiple glass sheets and make some "weird super massive window"

But.. how does this would work in real life? would many layers create bad coincidence dip? and what other downsides does it have in reality?


I wish they would make green glue in transparent and it would really glue things together :D


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 Post subject: Re: Glue leaf layers
PostPosted: Fri Jun 11, 2021 11:01 pm 
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the laminated glass will mostly act as a single unit when done with the proper materials. on drywall - the green glue acts as a damping agent, in glass, the very thin laminate also acts to damp slightly. presumably with no air gap the resonances effectively even out as if it's a single unit but you would have to verify empirically to determine.

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 Post subject: Re: Glue leaf layers
PostPosted: Fri Jun 11, 2021 11:40 pm 
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I am just wondering what the benefit is? Is this proposed window for a single leaf assembly with a high amount of mass?

If it's for a double leaf assembly then it would be cheaper and more effective to use two panes separated by an air gap anyway.

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 Post subject: Re: Glue leaf layers
PostPosted: Sat Jun 12, 2021 1:19 am 
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it's often 2 laminated glass panes separated by an air (usually an inert gas in sealed units or the structural frames). the laminations also provide some of safety without the restrictions of tempered glass.

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 Post subject: Re: Glue leaf layers
PostPosted: Sat Jun 12, 2021 3:21 am 
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gullfo wrote:
it's often 2 laminated glass panes separated by an air (usually an inert gas in sealed units or the structural frames). the laminations also provide some of safety without the restrictions of tempered glass.


Sorry Glen, I understand the various types of glass and what they consist of - I was directing my question at the OP. I am wondering what is the benefit of building up multiple layers of glass and PVB instead of the usual approach of using two laminated/toughened panes with an air gap...

As there's little benefit in having a window which has more surface density than the wall into which it's installed either the proposed window is for;

1. a very dense single leaf where the surface density of the wall is greater than the maximum available laminated thickness, and said wall is very thin so an appropriate MSM equivalent cannot be achieved using 1 pane or there is not room for big enough of an air gap between 2 panes...

or 2. the OP already has lots of thin glass which he is hoping to turn in to denser units using the PVB sandwiched between multiple panes, which would save money.

I am just being nosey, basically :lol:

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 Post subject: Re: Glue leaf layers
PostPosted: Sun Jun 13, 2021 4:20 am 
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thanks Paul!

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 Post subject: Re: Glue leaf layers
PostPosted: Wed Jun 16, 2021 10:30 pm 
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Paulus87 wrote:
gullfo wrote:
it's often 2 laminated glass panes separated by an air (usually an inert gas in sealed units or the structural frames). the laminations also provide some of safety without the restrictions of tempered glass.


Sorry Glen, I understand the various types of glass and what they consist of - I was directing my question at the OP. I am wondering what is the benefit of building up multiple layers of glass and PVB instead of the usual approach of using two laminated/toughened panes with an air gap...

As there's little benefit in having a window which has more surface density than the wall into which it's installed either the proposed window is for;

1. a very dense single leaf where the surface density of the wall is greater than the maximum available laminated thickness, and said wall is very thin so an appropriate MSM equivalent cannot be achieved using 1 pane or there is not room for big enough of an air gap between 2 panes...

or 2. the OP already has lots of thin glass which he is hoping to turn in to denser units using the PVB sandwiched between multiple panes, which would save money.

I am just being nosey, basically :lol:


Thank you both!
as I said this is a partly a brain teaser and part thinking could I really use this.
on the practical side could I just add layers to my existing window "leafs".
I have double glazing windows, but glass is thin and options would be to change whole window or try to install thicker glass (or add mass/layer to existing glass)

I replaced one glass with thicker one, but I noticed it would be just so much easier if you could somehow glue/melt PVB-foil with heat gun etc. to get more glass.

thinking the theory again:
what if the glue/laminate is hard like epoxy and not "like green glue", would this be good/bad in leaf (and will this be valid in both gypsum and glass, no airgaps just layer(s) of material glued together to form a one leaf in example in MSM wall)


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 Post subject: Re: Glue leaf layers
PostPosted: Thu Jun 17, 2021 6:44 pm 
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I would not use the existing double glazed units, they're very resonant.

Whenever you glue layers together they become stiffer and therefore more reflective. With enough mass this means better sound proofing since the sound will bounce off back in to the room instead of transferring energy through the assembly.

When the layers are not glued, they are limper and allowed to slide against each other which means some absorption will happen via the assembly itself. Similar to how membrane traps work.

So there's two approaches; build a room very heavy and very solid to bounce all that energy back, or build a limp bag that will be more easily excited by the sound hitting it which will vibrate, causing the air on the other side to vibrate and having the illusion of some of the sound passing right through the wall, using up some of that sound energy in the form of absorption. Add damping into the mix and you end up with an effective isolation assembly with less internal acoustic issues.

Imagine kicking a ball at a solid concrete wall vs a thick hanging drape for example.

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 Post subject: Re: Glue leaf layers
PostPosted: Thu Jun 17, 2021 9:35 pm 
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Paulus87 wrote:
I would not use the existing double glazed units, they're very resonant.

Whenever you glue layers together they become stiffer and therefore more reflective. With enough mass this means better sound proofing since the sound will bounce off back in to the room instead of transferring energy through the assembly.

When the layers are not glued, they are limper and allowed to slide against each other which means some absorption will happen via the assembly itself. Similar to how membrane traps work.

So there's two approaches; build a room very heavy and very solid to bounce all that energy back, or build a limp bag that will be more easily excited by the sound hitting it which will vibrate, causing the air on the other side to vibrate and having the illusion of some of the sound passing right through the wall, using up some of that sound energy in the form of absorption. Add damping into the mix and you end up with an effective isolation assembly with less internal acoustic issues.

Imagine kicking a ball at a solid concrete wall vs a thick hanging drape for example.

Thank you! great explanation!


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