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PostPosted: Fri Aug 21, 2009 6:45 am 
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Okay, I know this has been addressed in the past, but I would really appreciate to hear from someone who really has experience in hardening the edges of O.C. 701, 703, 705 etc.

I'm working on finishing up my home studio and building panels out of 703 to be covered with GOM. I plan to use impalers mounted on 1"x2" strips in order to space the panels 2" off of the walls. The studio that I work in by day had their panels made by someone in Nashville TN and they have hardened edges, and look beautiful. They're as hard as wood along the edges, and you could cut your fingers on the corners!

I contacted the maker and asked if he'd tell me what he used to do the hardening, but he said it was a "trade secret." He did hint to me that you could actually use Elmer's glue products to achieve similar results. I've tried spraying on Elmer's white glue, and Elmer's wood glue, which can be purchased by the gallon at hardware stores. They do work, and are non-toxic thankfully, but they take forever to dry, and obviously don't set up with nearly the same effect.

I have a compressor, and a sprayer. I've worked with resins and hardeners before, and if anybody has any advice on the best kind of resin, method of application, or if I'm just plain crazy for even attempting this myself, then I'd appreciate any and all help.

Thanks so much.

Jim
Nashville, TN


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PostPosted: Fri Aug 21, 2009 11:47 am 
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I am going to guess here.

Hardening the edges defeats the purpose of the product so if I were making this item then in my shop we would develop a perimeter around the panel, rounded edge, sharp, whatever you want really, Roman ogee, it can be done.

Spraying the material changes the properties and affects how it performs in the acoustic arena.

I think they may have been bs'ing you, but people do all kinds of things when money is no issue.

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PostPosted: Fri Aug 21, 2009 8:06 pm 
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X is right.

A non-hardened panel will absorb more/better since the edges will be exposed.

You can create a frame made out of wood, metal (a metalstud for example!) to get a cool looking panel. Check realtraps for example. The look fantastic. Notice the cuts on the edges, that gives it more exposed wool and therefor better absorbing properties.

Hey, you can even make a "plastic" transparent frame. Might be cool, dunno. :)


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PostPosted: Sat Aug 22, 2009 1:18 am 
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Slipperman wrote:
He did hint to me that you could actually use Elmer's glue products to achieve similar results.


I think he's trying to throw you a curve ball. I've never done this, but I have read many times that the way to do it is with 2-part epoxy applied in one or two thin coats with a paintbrush. Of course the other comments are correct about losing a little absorption. It's no big deal on a panel one inch thick. But when panels are four inches thick, having exposed edges adds 50 percent (!) more surface area. See the drawing and text below, from my article Alternative Test Methods for Acoustic Treatment Products.

--Ethan

Image

Figure 2: This panel is 2 by 4 feet by 4 inches thick. During testing the edges increase the total surface area by 50 percent, yet the edge surface is excluded from the calculation to absorption coefficients from sabins. Further, when a group of panels is mounted adjacent to cover an entire wall or ceiling, none of the edge surfaces are exposed, even though some of those surfaces absorbed during testing.

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PostPosted: Sat Aug 22, 2009 1:34 am 
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:shock: OMG Ethan. I was just writing a reply, but decided to check the date of the authors post first. I come back and low and behold..you posted what I was going to suggest.

As to the real product, I believe GELCOAT is the name. It is the resin used for "fiberglass"..and seeing how 703 IS fiberglass..it might work good. Although I would use the woven fiberglass "cloth" as a "structural" element. Thought about doing this myself at one time.

Hey, getting back to the "exposed edge" adding absorption issue...wasn't there a huge war about this. :mrgreen: I thought the battle line was the "exposed edge" wasn't the cause of 1+ coeffcients... :oops: maybe I shouldn't go there. :horse: :roll: :mrgreen:

Anyway, getting back to this "hard edge"..if the panels are covered with fabric, whats the point? Seems like just using wood or even metal angles would do the same thing..only MUCH eaiser. And less messy. :mrgreen:

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PostPosted: Sat Aug 22, 2009 1:36 am 
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OMG, whats going on. The PICTURE just appeared....my bad. :shock: :roll: :oops:

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PostPosted: Sat Aug 22, 2009 2:05 am 
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"GELCOAT" is the surface and coloring coating applied to the waxed surface of the mold(former) when a fiberglass object is made. It gives the object a smooth, shinny, colored surface. It is very brittle by itself. Not what we need for this application. A resin is what is needed.

Try this link:

www.defender.com/category.jsp?path=-1|10918&id=12212

It's the maintenance/ resin section if the link gets lost.

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PostPosted: Sat Aug 22, 2009 2:39 am 
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Quote:
It is very brittle by itself. Not what we need for this application. A resin is what is needed.

:shock: Hmmm, I used Gelcoat back in the 80's for Signage projects and it wasn't brittle. Of course I'm no expert. I thought Gelcoat WAS the resin :oops: Oh well, Ah learn somthin nu evra daigh! :mrgreen:

Thought about making molds for frames like these. Now I know what the Gelcoat is for. Thanks. Who needs boring absorption! :mrgreen:
Image
Image
Image
Image
Image

I love Diamond theory. And now I see Auralex took me seriously. :roll: :mrgreen:
I forget the name of their product, but it uses DOUBLE Diamond theory(split and inverted) to do things like this.
Image
fitZ

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PostPosted: Sat Aug 22, 2009 3:36 am 
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I think that Polyester or Epoxy Resin is what this job needs. Probably the Polyester Resin, as it's less expensive and easier to work with. The virtues of Epoxy don't apply here (but they do if you are building a boat).

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PostPosted: Tue Aug 25, 2009 1:56 am 
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cadesignr wrote:
wasn't there a huge war about this. :mrgreen: I thought the battle line was the "exposed edge" wasn't the cause of 1+ coeffcients.


It only makes sense that exposed edges presents more total absorbing surface to the room. Now, it may be that even when the edges are sealed there's slightly more absorption than the front surface area would imply. But it can't be more, or even as much as when the edges are exposed. At one point in that discussion Jeff Szymanski guesstimated the difference. As I recall, he figured that reflective edges absorb about 25 percent of what you'd get from absorbing edges.

--Ethan

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PostPosted: Thu Mar 07, 2019 3:26 am 
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I recently discovered (by accident in a way) that the stuff called "No-Frame Edge Hardener" is actually Roman-543 or Roman-838 adhesive that you can buy at any good hardware store, including Home Depot. I had recently used the 543 for a wallpapering project and then went out and bought the No-Frame Edge Hardener because there was no other recommendation online. With shipping it was $25/quart the Roman-543 and Roman-838 is about $25/gallon and readily available. When I opened the No-Frame super generic can it smelled exactly like the Roman adhesive. I open the Roman adhesive and gallon jug with some left over and sure enough, its the exact same stuff only the dilute the No-Frame down a bit with water. I tried both on a 703 panel and they hardened up exactly the same. It worked great for DIY panels with no frame. So if you want to save some money and hassle I would recommend buying the Roman products, it's just glue that soaks into the fiberglass and hardens up. Hope this is helpful to someone!


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PostPosted: Thu Mar 07, 2019 4:22 am 
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As many others have already said, hardening the edges greatly reduces the acoustic absorption of the panel, and I honestly can't think of any good acoustic reason why you'd want to do that.

- Stuart -

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 Post subject: Differing
PostPosted: Fri Mar 08, 2019 7:30 am 
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I have seen this discussed at length before. Non intuitive perhaps, but my take-away was that framed or hard edged panels benefit from edge effects which add up to be approximately equal in absorption to soft edges.
https://www.gearslutz.com/board/showpos ... stcount=37
https://www.gikacoustics.com/diy-acoustic-panel-frames/
DD


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PostPosted: Wed May 15, 2019 12:49 am 
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Location: Dallas,Tx / New Orleans, LA
I used clear fiberglass resin on the 4 corners of my 703 panels. Just mix the resin then use a paint brush to apply small strips about 2-3" long. The edge harden and made the panels a little easier to grad an move around without crushing the edges. Next time I will also do a small section at the middle edge as well.


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