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Box builders yellow glue

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Post Options Post Options   Thanks (0) Thanks(0)   Quote bee Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2017 at 10:09pm
Originally posted by I-shen Soundboy I-shen Soundboy wrote:

Originally posted by SouthwestCNC SouthwestCNC wrote:


if you can imagine the ply laminates that are already saturated both sides in phenolic glue that has the full un restricted ability to penetrate into that laminate

I don't believe the phenolic penetrates the ply laminates to an appreciable degree - the plys (surface and core) will suck up considerable amounts of liquid on their edges.

Stain some ply, then section: Observe how deeply the stain penetrates the edges but not the first phenolic glue layer (staining a surface, the stain won't penetrate past the first ply, but staining an edge it will go a few mm deep).

The phenolic resin is waterproof, but it doesn't impart this to the wood plys. Plywood in a puddle will warp and swell, but the glue does a job of holding it all together.
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SouthwestCNC Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2017 at 10:31pm
thats one way of looking at it. Another way would be to imagine taking an 18.2mm strip of birch hardwood compressing it into 17.7mm thickness (as to match the wood content in compressed ply) and dipping its end grain in a set amount of stain until it had soaked it all up. Now repeat with an exact same size piece of ply and then compare how long it took and how far it penetrated. That will give you a comparison as to it permeability. I wouldn't be at all supprised if the difference was over 50%.

Edited by SouthwestCNC - 12 April 2017 at 10:42pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote I-shen Soundboy Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2017 at 10:39pm
Originally posted by bee bee wrote:

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Uh, thanks...
I've spent a little time investigating longboard (skateboard) layups. Those nutters are damn serious about their plywood, up to the point of custom lamination using fibreglass or carbon fibre, orientation of grain and particular attention to glues and pressure moulding.

It's a way away from DIY with 18mm BB/CP, but worth seeing what we could learn.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SouthwestCNC Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2017 at 10:50pm
ok now to stir things right up. What's your opinions of pu vs PVa in regards to panel resonance? :o
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowflake Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2017 at 10:53pm
some plywood you can see the glue as a distinct layer in between the laminates - doesn't look like it soaks in very much at all. other grades of ply seem much denser and it is harder to separate the layers.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote I-shen Soundboy Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2017 at 10:59pm
Have ten ton press and buckets of stain, but birch hardwood I'm right out of, so I'll skip that midnight experiment. The phenol isn't going to absorb glue, but it will stick to the joint.

Key takeaway is butt jointing ply will only allow glue penetration one ply thick where plys are parallel to joint, but much deeper penetration where plys are perpendicular to joint.

Practically, a rebate, dowel, biscuit or even screw hole will expose more core plys to glue, which is why they're more useful in laminate woodwork than timber.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SouthwestCNC Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2017 at 11:13pm
Originally posted by I-shen Soundboy I-shen Soundboy wrote:

Have ten ton press and buckets of stain, but birch hardwood I'm right out of, so I'll skip that midnight experiment. The phenol isn't going to absorb glue, but it will stick to the joint.

Key takeaway is butt jointing ply will only allow glue penetration one ply thick where plys are parallel to joint, but much deeper penetration where plys are perpendicular to joint.

Practically, a rebate, dowel, biscuit or even screw hole will expose more core plys to glue, which is why they're more useful in laminate woodwork than timber.


I don't blame you lol, there will be loads of factors at work, grain distruption in ply layers will slow it for sure, surface tensions on the phenolic layers. It's going to be slower to absorb that's a cert. really the test would be better to compare standard ply with phenolic bonded ply. I don't know exactly how relevant the uptake of stain is to how far either glue penetrates tho in reality. Both are perfectly good at creating a strong joint when used in joints where more laminates are exposed by dowels rebates etc, and like you say how strong can a butt joint be when glued to a single laminate.

Edited by SouthwestCNC - 12 April 2017 at 11:16pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote I-shen Soundboy Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2017 at 11:15pm
Originally posted by SouthwestCNC SouthwestCNC wrote:

ok now to stir things right up. What's your opinions of pu vs PVa in regards to panel resonance? :o

Haven't a clue, but in theory the harder glue should provide the strongest inter-panel fixture. In practice, the hardness/viscosity might affect damping... ?
The difference is probably too small to measure or isolate from other variables.

How about building damping into the panels: Sandwich a sheet of cork between two sheets of 9mm plywood (don't start on which glue to use...) and use that to make a cabinet. The differential in material transmission properties should show a marked improvement over straight 18mm lined with cork on the surface (as a control)

Again, probably one for the morning...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SouthwestCNC Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2017 at 11:19pm
Originally posted by I-shen Soundboy I-shen Soundboy wrote:

Originally posted by SouthwestCNC SouthwestCNC wrote:

ok now to stir things right up. What's your opinions of pu vs PVa in regards to panel resonance? :o

Haven't a clue, but in theory the harder glue should provide the strongest inter-panel fixture. In practice, the hardness/viscosity might affect damping... ?
The difference is probably too small to measure or isolate from other variables.

How about building damping into the panels: Sandwich a sheet of cork between two sheets of 9mm plywood (don't start on which glue to use...) and use that to make a cabinet. The differential in material transmission properties should show a marked improvement over straight 18mm lined with cork on the surface (as a control)

Again, probably one for the morning...


Yeah not getting into this one lol. Damping without storing and releasing delayed energy.. all very complicated. Does gold wire produce better sound quality than copper lol.

Edited by SouthwestCNC - 12 April 2017 at 11:20pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote I-shen Soundboy Quote  Post ReplyReply Direct Link To This Post Posted: 12 April 2017 at 11:46pm
Depends, do you want to knock out good honest boxes for good honest people, or mahogany veneer some audiophile voodoo mumbojumbo​ and see just how rich you can get?

You're going to have to claim to use something fancier than Soudal PU for a start: Try luthier's hide glue from pashmin goats, applied with a badger bristle brush, of course 😉
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bee Quote  Post ReplyReply Direct Link To This Post Posted: 13 April 2017 at 12:12am
lol....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bee Quote  Post ReplyReply Direct Link To This Post Posted: 13 April 2017 at 12:13am
ive never been a fan of the expandable glues with ply. more a personal choice.
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