Gorilla Glue OK For Rocker Glue Up?

[Derek Arita]

Just wondering if Gorilla Glue works well for a rocker glue up of 4, 1/4" laminates? Will it give me enough open time?

[Mort Stevens]

Gorilla Glue has it place in the shop (mostly gluing metal/rubber to wood), but when the glue really matters I reach for epoxy.

[Richard Coers]

Are you talking their white glue, or poly?

[Malcolm Schweizer]

If you mean their PVA glue, no- it expands and foams and therefore is not good for laminations. It would cure too quickly and require huge amounts of clamping force. Go with yellow wood glue or better yet epoxy. I always use epoxy for laminations, especially for rockers where there is a lot of force put on the part.

[Mike Henderson]

I've used PVA for bent lamination for rockers, and Maloof used the same on his rockers. If you don't like that, urea formaldehyde is very good and gives you a long open time.

I don't know about the open time on Gorilla glue but the foaming is a mess.

Mike

[jack forsberg]

Hi Mike

I don't think SAM used it for the rockers? only the leg joints IIRC and i'm not sure he keep up with it?

i been wrong before though.




I've used PVA for bent lamination for rockers, and Maloof used the same on his rockers. If you don't like that, urea formaldehyde is very good and gives you a long open time.

I don't know about the open time on Gorilla glue but the foaming is a mess.

Mike

[Steve Milito]

If you mean their PVA glue, no- it expands and foams and therefore is not good for laminations. It would cure too quickly and require huge amounts of clamping force. Go with yellow wood glue or better yet epoxy. I always use epoxy for laminations, especially for rockers where there is a lot of force put on the part.

The foaming, messy Gorilla glue is a polyurethane glue. Yellow glue (titebond) and white glue (Elmer's) are a polyvinyl acetate (PVA) glues and don't foam.

[Mike Henderson]

Hi Mike

I don't think SAM used it for the rockers? only the leg joints IIRC and i'm not sure he keep up with it?

i been wrong before though.
Nope, I specifically asked him which glue he used on the rockers (once when I visited his shop). He pointed to a couple of bottles of Titebond and said, "I use the light colored one on light wood." I was very clear that I was asking him about the rockers themselves.

Mike

[Mikail Khan]

I use a white PVA glue. Hal Taylor recommends Titebond in his plans. Gorilla glue now sells a white PVA glue in addition to the original polyurethane Gorilla Glue.

[marty shultz]

I use PVA gliue in AZ on rockers and it works good. To keep if from drying out too fast you can stack the lams as you glue them so the air doesn't dry out the glue.

[Art Mann]

The "open" time of Gorilla glue is actually considerably longer than any of the PVA glues. I have used it a few times for that reason. Mostly, I think its foaming properties and long clamp times make it undesirable for woodworking.

[Jamie Buxton]

For bent lamination, here's the possible glues and their pros and cons....

PVA (common brands Titebond, Elmers) The knock on PVA is that it cold creeps. That is, even though it looks solid, it actually flows very slowly under pressure. For bent lamination, the fear is that the glued-up piece would slowly change shape. I used PVA for bent lamination long before I heard of cold creep, and didn't notice any shape changes. So maybe this issue is more theoretical than practical. However, it is easy enough to use non-creeping glue, so that's now what I do.

Polyurethane. (Common brand Gorilla Glue). Non-creeping. One issue is that it foams up as it cures, and gets over everything. It bonds to everything, so clean-up is a big nasty. The other issue is that the glue itself seems weak. I've tested PU joints to failure, and it was the glue that failed. In contrast, if I stress PVA joints to failure, it is the wood that breaks. So I don't recommend PU for bent lamination.

Urea-formaldehyde. (Unibond 800 and others). Non-creeping. Open time measured in hours. I used this for a long time, but my worry is the formaldehyde exposure. Formaldehyde is carcinogenic. I was never able to understand how much formaldehyde is outgassed by the glue, nor how much would be toxic, so I eventually gave it up for epoxy.

Epoxy. (West Systems, System Three). Non creeping. Open time in hours. No foaming, no concerns about toxicity. Strong bond to wood. It is what I use now for bent lamination.

[Mel Fulks]

Another glue thread! Since most of the laminations I've done have been for trim that would ultimately be nailed to something I don't hesitate to thin PVA or use water mixed plastic resin glue. I don't know how many lams you will be using
but I'm pretty sure that even though the rockers are freestanding its probably enuf that spring back will not be a pproblem and I wouldn't be concerned about creep if the chairs designer used PVA. I like to put glue on both sides on that type wwork and that is less messy if you thin it .As Peter said ,5 percent water. Have no idea why I'm getting more letters from computor than I'm ordering .Fan letters?

[Curt Harms]

Re polyurethane glue and foaming. I wonder if we tend to use too much water when prepping joints. From what I've gathered, it's not necessary to wet joints at all in humid climates, arid or semi-arid is another story, polyurethane requires some moisture or it won't cure. Too much moisture=lots of foam=weak joints.

[Mike Cutler]

Derek

It would be my last choice. It is a mess too work with.
Epoxy would be my first, but only because I work with it so much and am comfortable with it. It takes fewer clamps than a traditional PVA glue up. Open time, pot life, can be minutes, to hours, based on ambient air temp and hardener selection.
I'm certain Titebond Extend will work fine also, and should give you more than enough open time to lay up the rocker plys in the form, and get the clamps on.

Are the rocker plys pre bent ?

[Lee Schierer]

Most people dampen their wood when using Gorilla glue and get lots of foaming as a result. I've found that there is enough moisture in the air and in the wood to use it without wetting the wood first. As a result, when I use it, I get far less foaming and the bonds are still strong. It does give you longer open times than PVA and some epoxies, It is waterproof. The claim that the foaming action fills voids is true, but teh foam is not very strong so you still need tight joints for strength.

[Chris Fournier]

It seems like many folks have an aversion to PU glues. Personally I consider it a very important and useful glue in my shop - for the right applications. If used properly there really isn't much foaming and it cleans up easily and is easy on tools. I can't understand why so many folks reach for epoxy so quickly, it is usually a poor choice for several reasons, again the caveat to this is that it is the right glue for some jobs. Why a poor choice? It is quite toxic relative to other adhesives, it is very messy, it is hard to clean up, it is tough on cutting tools.

If you are asking about bent laminating furniture parts I would reach for two part plastic resin glue for critical jobs or powdered plastic resin glue for run of the mill work. Why? Very cost effective, long open time, ease of use, not as toxic as epoxy, has the colour tone of many woods, easier on cutters than epoxy, doesn't creep, cold waterproof. One word of caution though, the squeeze out can be as sharp as glass, handle carefully.

I don't often use PVA for bent lams unless the lay up forces invloved are very minimal. I am not one to knock PVA, it is high value and handles the lion's share of gluing tasks in a woodshop beautifully.

Adhesives can make or break a project or a budget it pays to research!

One final thing, if you are colouring a project prior to top coating, choose your adhesive wisely, some take colour, most don't. Of course tight glue lines go a long way!

[Derek Arita]

I watched a YouTube vid where the guy did a rocker glue up and recommended Gorilla Glue, because it doesn't creep.
Are all Titebond yellow glues, PVA type? Is epoxy glue a more complicated glue to use?

[Sam Murdoch]

PVA type? Is epoxy glue a more complicated glue to use?

No it is not complicated. Epoxy will do a good job easily. I have recently glued up some curved rails for some benches using 3-1/2" x 3/4" with 1/8" laminates of cherry with West System epoxy and it went very well. There was some release from the intended curve but I believe that release is an expected result with any glue. You need to overbend a bit if your curve is critical.

[Cody Colston]

I just finished my fourth Hal Taylor rocking chair and on this one, I used Dap Weldwood Plastic Resin Glue on the bent lams for the rockers and back braces. I used TBIII on the previous builds. I think I'll stay with the PR glue on future builds because PVA glue has such a short open time and it also creeps. I like and use West System epoxy a lot but it doesn't want a lot of clamping pressure which is necessary for bent lams. I keep a very small bottle of Gorilla Poly glue for certain things but would never use it for bent lams or anywhere the wood will be stressed. The bond is too unpredictable in my experience. YMMV

[Mike Henderson]

One issue with both epoxy or urea formaldehyde (some people call it "plastic resin") is that you have to mix up more than you think you're going to need because you generally don't want to run out when you're in the middle of a glue up. Urea formaldehyde is not as expensive as epoxy so that's a bit less of an issue for it, but it does give off some formaldehyde during the curing process. I use it in a well ventilated area so I'm not that concerned about the formaldehyde.

Also, epoxy will generate heat and can "go off" on you (harden in the container, fairly rapidly, too, even though it's indicated as slow epoxy) if you don't keep it cool. I put the mixing container in another container filled with ice.

Between the two, I mostly prefer epoxy.

Mike

[Mike Henderson]

No it is not complicated. Epoxy will do a good job easily. I have recently glued up some curved rails for some benches using 3-1/2" x 3/4" with 1/8" laminates of cherry with West System epoxy and it went very well. There was some release from the intended curve but I believe that release is an expected result with any glue. You need to overbend a bit if your curve is critical.
Any bent lamination will have some springback, no matter what glue you use. Sam's right, you have to overbend a bit to get the final curve.

My experience is that the amount of springback is affected by the number of lams. The more lams, the less springback. Maybe also affected by the thickness of the lams, but more so by the number.

Mike

[Sam Murdoch]

It helps to slow down the off period of epoxy if you mix it in a shallow bigger dish like a sandwich storage container (or bigger) rather than say a cat food can.

[Mel Fulks]

Yes ,plastic resin glue has a label too boring to read ! Like a lot of things. But the guide lines for coverage are accurate. For veneer and big lamination jobs where I insist on putting it on 'both surfaces' I thin it to "immediately drips,not runs ,
off a stick". I've kept my own notes on proper ratio for that. On a few occasions I've mixed as much as 15 or 20 pounds and hit it right. I use the weight directions for powder and water on all but the smallest needed quantities .You save a lot of money by ordering 25 pound container. Shelf life is rated six months to a year,but I've taken as long as three years to
use 25 pounds by dipping out the powder quickly and closing container just as quickly. I keep silica gel in it ,whole container in plastic bag ,and store the whole thing in air conditioning in summer and shop in winter.

[Derek Arita]

Well, I just picked up a can of West epoxy and hardener. I got it at a boat supply, so I hope it's the right West epoxy. Using it as a glue seemed to be their last experience with stuff, so they didn't offer much info for it. Anyhow, I got the slow hardener. They only had fast and slow. Hope it's right. Also got filler. What consistency am I looking for?

[mreza Salav]

Mike, I think the more important thing (that will help reduce or eliminate spring back) is the thickness of plys. With 1/16" or so plys I think you get very little (if any at all) spring back.
At least that has been my experience.

[Chris Fournier]

Any bent lamination will have some springback, no matter what glue you use. Sam's right, you have to overbend a bit to get the final curve.

My experience is that the amount of springback is affected by the number of lams. The more lams, the less springback. Maybe also affected by the thickness of the lams, but more so by the number.

Mike

If you are careful with ply thickness there is no need to experience any measurable springback. It takes a bit of experience and experimenting but I don't consider springback to be inevitable and in many designs and applications it's unacceptable. The right glue, the right glue up and parts pop out of the mold like they are injections.