Darryl Keil Last Activity 2025-02-12 2:48 PM
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frank thomas

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Joined: 2008-01-04
Location: Folsom

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Subject : one part glue that cures inside vacuum bag?
Posted : 2008-07-09 4:07 PM
Post #34687

Are there any one part glues that will cure inside the vacuum bag?


 
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Darryl Keil

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Joined: 2003-05-22
Location: Maine

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Subject : RE: one part glue that cures inside vacuum bag?
Posted : 2008-07-10 12:14 PM
Post #34688 - In reply to #34687

Frank,

Unfortunately there is no one part glue that will fully cure in the bag, bond yes, but not cure. Any PVA glue (white and yellow glues) will achieve the bond phase in a vacuum bag. This happens by the water in the glue being drawn into the substrate and veneer through a combination of force and capillary action which pulls the glue in with it. This bond phase does not require air to bond the two surfaces together. Its the same principle that allows you to glue two boards up in clamps and then take them out in as little as 5 minutes, provided you don't work the boards. The cure phase takes place when all the water leaves the glue joint which does need air circulation.

Although not a true one part glue, polyurethane adhesive will cure in the bag along with the other two part glues.

Sincerely
Darryl Keil


 
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BigRob777

Posts: 142

Joined: 2008-05-26
Location: Newark, DE

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Subject : RE: one part glue that cures inside vacuum bag?
Posted : 2008-07-10 5:13 PM
Post #34689 - In reply to #34688

Man, you really know your stuff Darryl.
Rob


 
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Brian Gray

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Joined: 2004-01-21
Location: Sandusky, OH

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Subject : RE: one part glue that cures inside vacuum bag?
Posted : 2008-07-10 9:09 PM
Post #34690 - In reply to #34689

Darryl is the man.




 
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Darryl Keil

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Location: Maine

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Subject : RE: one part glue that cures inside vacuum bag?
Posted : 2008-07-11 9:09 PM
Post #34691 - In reply to #34689

Rob,

Well, there is a story behind my explanation that goes like this. Quite a few years ago I was at the very first trade show we ever did with the vacuum press and someone came up to me in our booth, looked at a part that I had sucked down in the bag and said, "how does the glue dry in the bag". Well I had never even thought about that before as the veneer had always stuck for me just fine, so I knew it worked. Being quick on my feet I said, "there's no more air circulation a 1/4" in from the edge on a conventional platen press than there is in a vacuum press" This seemed to satisfy him but I did make a mental note that I wanted to understand the process with PVA glues and give a better answer than that.

After the show I contacted someone I knew who was and expert in the glue field and he explained to me about the bond and cure phase of PVA glues, which of course made perfect sense when I heard it, I had just never thought of it before. It did get me thinking though, which was the beginning of the development of Unibond 800.

I will ad this, which is the first time I've put this out anywhere, we are in the early stages of attempting to develop a new glue that would still be catalytic like Unibond 800 but be as "green" as possible. I make no promises about our success or how long it will take but we are working on it. Stay tuned.

Darryl


 
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BigRob777

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Joined: 2008-05-26
Location: Newark, DE

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Subject : RE: one part glue that cures inside vacuum bag?
Posted : 2008-07-11 11:35 PM
Post #34692 - In reply to #34691

Darryl,
OK, now I'm going to show my newbieness. What is unibond 800? I've heard of it many times in this forum, but don't know what it is. I just bought a gallon of some sort of yellow glue, with pecan shells ground up in it to clog the pores of open grained veneer, but I'm really open to better things.

I'm guessing that it's a catalytic type glue, that cures in the bag.
Thanks,
Rob


 
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Brian Gray

Posts: 339

Joined: 2004-01-21
Location: Sandusky, OH

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Subject : RE: one part glue that cures inside vacuum bag?
Posted : 2008-07-12 7:29 PM
Post #34697 - In reply to #34692

Hey Rob.

In my opinion, Unibond 800 is hands down the best veneer glue out there.

There's only a couple of applications where I won't use it.

You can read more about it here.

http://www.vacupress.com/veneerglue.htm

Make sure to pick up some. You'll never use yellow glue again.

Yellow glues contain water. This will quite often lead to the veneer buckling and rippling when it absorbs all that water.

There's been a couple of projects that I've done that have completely flopped by using a yellow glue.

That being said, there's plenty of guys that use yellow glues without any problems, but I'm not one of them. The advantages are that yellow glues bond faster, and you don't have to be as attentive to the shop temperature. But those two items are not enough for me to learn how to use them, when Unibond is so simple (and I'm pretty sure that Unibond will give a much stronger bond, regardless)

And Darryl...you've got my attention! I can't wait to hear more about this new glue.


 
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BigRob777

Posts: 142

Joined: 2008-05-26
Location: Newark, DE

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Subject : RE: one part glue that cures inside vacuum bag?
Posted : 2008-07-12 8:55 PM
Post #34698 - In reply to #34697

Well, I certainly can't argue with that kind of logic. Is that the glue that Darryl uses in his 2nd video? I hope this is OK, as it isn't my thread. I don't want to hijack it, if all questions aren't answered.
Rob


 
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Brian Gray

Posts: 339

Joined: 2004-01-21
Location: Sandusky, OH

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Subject : RE: one part glue that cures inside vacuum bag?
Posted : 2008-07-13 1:02 PM
Post #34699 - In reply to #34698

I'm pretty sure that the glue in the vidoes are Unibond, but I'm going off of memory.



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