Outdoor capable laminations

[Brian Holcombe]

Afternoon gents. I'm building a chair which will spend its life outdoors, but will be sheltered from the rain and snow and actually the majority of the sun.

For the back, I'd like to do a bentwood lamination, rather then attempt to steam bend the mahogany that I will be using. In doing so I need a glue that will not creep and will be capable of surviving in mildly harsh outdoor conditions.

Thanks in advance.

Cheers
Brian

[Mike Henderson]

Titebond III will work for you. Sam Maloof used titebond on all his rockers, and he laminated the skate.

I've done a fair amount of laminate bending with Titebond and no problems with creep or anything else.

Otherwise, use a UF glue or epoxy.

Mike

[James Waldron]

Afternoon gents. I'm building a chair which will spend its life outdoors, but will be sheltered from the rain and snow and actually the majority of the sun.

For the back, I'd like to do a bentwood lamination, rather then attempt to steam bend the mahogany that I will be using. In doing so I need a glue that will not creep and will be capable of surviving in mildly harsh outdoor conditions.

Thanks in advance.

Cheers
Brian

For outdoors (and in my case, on boats), it's hard to outperform a two part epoxy. For convenient sourcing and convenient guidance and convenient usage, I'd suggest West System, http://www.westsystem.com/ss/ ; System 3, https://www.systemthree.com/ ;or if you don't mind a messy web site (but with a good price point), you can go to Progressive Epoxies, http://www.king-cart.com/cgi-bin/cart.cgi?store=epoxy . The West site has really good tech information and the tech service people there are quite helpful by phone or e-mail if needed.

The one area to be careful about is the need to protect exposed epoxy (i.e., coatings, not glue lines) from uv exposure (sunlight in particular), as it will yellow over time (in the tropics, over a frustratingly short time). A good marine varnish over the surface will do, but as with any outdoor varnish finish, the varnish will need refreshing from time to time.

For laminating wood, it's good to add a reinforcing filler (cotton flock or milled glass fibers) to the mix. If you laminate with oily tropicals (teak, etc.) or with acidic wood (white oak, etc.), wash the bond surfaces with acetone and allow the residual acetone to evaporate before applying adhesive mix.

For the record, Titebond I, II and III will creep over time under stress, as in a bent wood laminate. Read the label.

[Dave Anderson NH]

Another option which stands up well in marine use is resourcinol but it is becoming harder to find.

[Mike Henderson]

For the record, Titebond I, II and III will creep over time under stress, as in a bent wood laminate. Read the label.

I've heard that story many times but I've used Titebond for laminate bending in many different applications and never experienced any creep in the laminates. And as I mentioned earlier, Sam Maloof used Titebond for the laminate bends in his rockers and I've never heard any stories of creep in his furniture.

I asked Sam directly what glue he used and he pointed to a shelf where he had Titebond glue. He said, "I use one or the other depending on the color of the wood" referring to Titebond I or III.

Mike

[Brian Holcombe]

Thanks gents, appreciate the information. On a separate topic, should I be at all concerned with spindles being cut into a bent lamination?

[James Waldron]

Used indoors, with controlled temperature and humidity, stressed Titebond PVA glue laminate joint creep may not show up for decades. Outdoors, exposed to high temperature and high humidity, things are quite different and bentwood laminate failures can occur in a matter of a few months. That's why the labels warn about creep and explicitly disclaim use of Titebond PVA as a structural adhesive. Again, read the label.

Or live dangerously. You pays your money, you takes your chances.

[Eric Schmid]

For exterior furniture I'd use epoxy. Polyurethane glues also work well, but I don't like combating the expansion in a bent lamination. If you have several pieces to glue at the same time, a slow epoxy provides plenty of time to get the surfaces coated and clamped.

I got scared off from TB 3 when some post wraps came undone on me a few years back. It probably was not all the glue's fault, but we did a few with Polyurethane on the same job and none of those failed.

Keep in mind that much of my work lives fully exposed to the elements, so I tend to stay on the safe side. That's not to say TBIII would not be suitable for your chair, it might hold just fine. For me, the extra effort and mess of Epoxy and Polyurethane glues are offset by the peace of mind (assuming proper technique).

[Curt Putnam]

@ 150°F, TB III is weaker than the wood - confirmed by Franklin. I would use epoxy or a UF glue like Unibond 800.

[Derek Cohen]

West Systems epoxy. I used this to repair my surfboards and windsurfers for many years, plus it was the choice of custom builders. Today I use it in situations where woodwork is exposed to rain and sun. Excellent track record.

Use packaging tape over the formwork, and then wax it for release.

Regards from Perth

Derek

[Mel Fulks]

One glue company rep told me they can't say glues are structurally safe without paying for expensive Independant tests. If they don't think that is a market they get a big piece of they decline to pay for the testing even if they think the product would be approved. So I make my own judgements based on what info is available and type of job.

[Mel Fulks]

I agree with Mike that creep is not a big deal now. When white glue was big,it was. A perfectly surfaced mortise and tenon joint could need some more work the next day, and I remember pieces sent to finishing room would be sent back for fix.

[Pat Barry]

@ 150°F, TB III is weaker than the wood - confirmed by Franklin. I would use epoxy or a UF glue like Unibond 800.

The glass transition temperature of the west systems epoxy is less than 150F. Onset temperature for glass transition is about 125F. The epoxy loses significant stiffness / strength at increasing temperatures above this. For example, sitting baking in the sun. Better epoxies (industrial) are heat cured and have significantly higher Tgs. Now I can't say how west systems epoxies will perform in your application, just that epoxy is not the perfect answer. Epoxies are also notoriously hygroscopic (water absorbing) - this can lead to adhesion issues / delamination. Forgot to mention the more obvious issues of measuring the two parts, mixing, pot life, cleanup, bond line thickness. Again, epoxy not a perfect solution. If it were me I'd go with the TB3.

[keith wootton]

don't worry about the strength of your bent laminations. they will be at least as strong and resist bending as well as single piece of wood that is steam bent. and it will never lose any of it's bend over time in any weather. and much stronger than a piece sawn to shape.

i have had good luck with gorilla (polyurethane) glue. simple to use, plenty of open time, sets fast, and i think forgiving. any excess will ooze out and be easy to remove (use duct tape on cauls and straps), you can use lots of pressure, and you will get very little springback.

you will also be able to shape your pieces after laminating easier than if you you use epoxy that hardens any wood it soaks into....that said, west epoxy would be my second choice, but you have to be careful not to starve the joints.

good luck!

[Sam Murdoch]

Thanks gents, appreciate the information. On a separate topic, should I be at all concerned with spindles being cut into a bent lamination?

Not any more than with solid wood of the same dimensions. The laminations will actually be less compromised by the "interruptions" than the solid wood.