Best Epoxy For A Given Use

[GrossApproximator]

Hi all. I imagine that this topic has been beaten to death already, but I've had a hard time using the search feature and prefer to talk to real people (I'm assuming none of you are machines in hiding . . .)

I have 2 layers of plywood that are laminated together and subjected to stress (see the figure attached to this thread). Under pure tension, the plywood is quite resilient, but in bending (as depicted in the figure), the plywood is failing easily. I'm currently using wood glue to secure the layers together, but I'm wondering if epoxy will give a better bond. Which epoxy do you think would be best?

View attachment Figure 1.pdf

 

[CarVac]

Hi all. I imagine that this topic has been beaten to death already, but I've had a hard time using the search feature and prefer to talk to real people (I'm assuming none of you are machines in hiding . . .)

I have 2 layers of plywood that are laminated together and subjected to stress (see the figure attached to this thread). Under pure tension, the plywood is quite resilient, but in bending (as depicted in the figure), the plywood is failing easily. I'm currently using wood glue to secure the layers together, but I'm wondering if epoxy will give a better bond. Which epoxy do you think would be best?

Aeropoxy ES6209 hands-down, based on my experience. It soaks into wood more strongly than wood glue, and sets up an incredibly strong internal reinforcement that makes the bonding strength fully usable. Laminating epoxies are nominally thinner than ES6209, but they don't have the wood affinity and take a long time to work in.

Whether or not it'll make a big difference depends on what failure mode the plywood is exhibiting. Is the surface ripping off? Is the glue joint staying intact while the layers of the plywood come apart?

Also, just for your information, I am a robot.

For more info, look here: https://jcrocket.com/adhesives.shtml. It explains that at least in lap shear testing, the ES6209 soaked deep enough into the plywood to reinforce the joint between layers, making the bond itself the weak spot (!).

 

[jd2cylman]

Putting on smart a$$ hat.............

CarVac, do you get a cut of all the Aeropoxy ES6209 sold? You should, cause you really sell that stuff :wink:

Not trying to offed, just poking fun.

Smart a$$ hat off.

I think I will try that stuff next time I'm ready to order some. You've sold me on it. Just need to replenish my rocket money.

Adrian

 

[COrocket]

A properly applied wood glue joint should be just as strong if not stronger than the underlying material. Epoxy is overkill for a wood-wood joint. If it is failing too soon I would look into changing the material or the way the stress is applied to it.

 

[CarVac]

Putting on smart a$$ hat.............

CarVac, do you get a cut of all the Aeropoxy ES6209 sold? You should, cause you really sell that stuff :wink:

Not trying to offed, just poking fun.

Smart a$$ hat off.

I think I will try that stuff next time I'm ready to order some. You've sold me on it. Just need to replenish my rocket money.

Adrian

I could never be a salesman for a living, because I only sell things that I truly believe are good. Nonetheless, I wouldn't mind being paid a bit of commission...

Just make sure to get some squeezebottles and a pair of disposable funnels; it takes a good 20 minutes to get the stuff into the squeezebottles because of the pre-mixing viscosity, and the squeezebottles make it super-convenient later.

A properly applied wood glue joint should be just as strong if not stronger than the underlying material. Epoxy is overkill for a wood-wood joint. If it is failing too soon I would look into changing the material or the way the stress is applied to it.

That's a generalization. Most epoxies have poor affinity to wood, so they only soak into the very top few layers. ES6209 is magical, or something, but it soaks in really deeply. It makes the wood itself much more resistant to delamination, thus making the joint stronger than any wood glue joint.

 

[kenstarr]

Generic brand ketchup bottles! Cheapest bottle you'll find. Pour out the nasty stuff, clean, dry, fill with yummy resin and catalyst!

Think I paid around a dollar for each bottle.
Ken

 

[Chuck]

Generic brand ketchup bottles! Cheapest bottle you'll find. Pour out the nasty stuff, clean, dry, fill with yummy resin and catalyst!
View attachment 117042
Think I paid around a dollar for each bottle.
Ken

I just got some ES6209 gonna have to do this. Thanks for the picture!

~Chuck

 

[kenstarr]

Huh, I guess I need to figure out how to hold the iPad.
-Ken