What glue for wood + PVC?

[JonW]

For a speaker building project, I’ll be gluing a 2” PVC pipe to the rear of the speaker cabinet. It’s a port. What glue would be good for joining PVC and wood? I’ll monkey around with my standard, Titebond II, and see if that works. Just thought I’d ask for some opinions. Thanks.

-Jon

[gerti]

Canonical answer:

http://www.thistothat.com/

[sacherjj]

I wouldn't even bother with a wood glue. Try something more along the lines of Gorilla Glue or Epoxy. That is unless it doesn't have to carry any load. In that case, you will probably be fine with wood glue. Make sure to rough up the outside before gluing.

[just4funsies]

I've used both Gorilla Glue and epoxy for such a weld, and both worked quite well. instead of roughing up the PVC prior to gluing, I used a PVC primer to remove the gloss finish, let it dry, and then glued it up. Extra note about the Gorilla Glue... be sure to clamp or fixture the workpieces, because GG expands as it cures, and will force the workpieces apart if given the room to do it.

[spf45]

In addition to the type of glue used, I wonder if you can improve stability and gluing area by putting a sleeve on the PVC, inside the cabinet? If the port is in the back (or covered in the front with mesh/screen/cloth) you could put a sleeve on both sides and then the wood/pvc joint becomes less of an issue.

Just a thought.

[JonW]

Thanks guys,

How’s about Titebond Cold Press cement? From my other post, it looks like I’ll already be buying some of that to do some veneering work.

Gerti- what a fun web site, I didn’t know about that one.

Sacherjj- No, it doesn’t have to carry a load. But I want it to be strong enough such that it doesn’t fall off years down the road. OK, epoxy or Gorilla Glue.

Just4funsies- Right, forgot about roughing up the shiny surface. Thanks.

Spf45- That’s _exactly_ what I have in mind, some sleeves on each end of the pipe. I was wondering how to glue the PVC into the sleeves.

[mdutch]

I'd steer clear of wood-wood specialty glues for anything but their intended purpose. They depend on penetration to adhere, which is something you're not going to get in plastic. For plastic-to-wood, the best is a solvent-based glue that will "melt" the plastic and make a chemical bond. Next best is epoxy, which is plastic-based resin, inherently sticky, which then hardens.

Being an audio-engineer, the "goop" or any soft adhesive like butyl or silicone will give you a dampening effect at the point of contact, which would not be desirable in a resonant cavity like a speaker cabinet. Though you certainly don't want the reverse (vibration) to occur!

To check the adhesive you want to use for its solvent properties, I'd take scraps of PVC and paint some on, rub it around thick and thin, let it cure, then try to chip it off. See if it has "melted" and really bonded to the surface of the PVC, or has just dried onto the surface without real adhesion.

The above-mentioned PVC "collar" idea is okay if it meets your acoustical parameters and doesn't take up too much room in the cabinet. In that case, I'd use PVC-PVC glue, with it's accompanying purple "primer", available in a two-can package in your plumbing dept.

Since you KNOW PVC glue will melt the PVC, have you tried seeing how well it bonds to the wood you're using? If that adhesive has enough penetrating power to adhere well to the wood, your problem is solved.

[JonW]

Hey Dutchman,

Thanks for the tips. “Melting” the PVC a bit is a good idea. Nope, haven’t tried PVC glue yet because I don’t happen to have any around the house. I can pick some up and try, though.

I’m not concerned about the collars taking up too much space in the cabinet because I’m building my own cabinets. I was just going to take the collar (and the associated bracing) volume into account in planning the cabinet dimensions. On paper, at least, I like the design I came up with that will both provide a collar for the PVC port and also brace the cabinet sides to reduce some of the vibrations. We’ll see if it really works out well or not when time to build it arrives.

[just4funsies]

The problem with PVC solvent cement is that it can't "melt" the wood. Just dried on the surface, it makes a poor bond. The stuff is not structural at all, and requires that the two pieces melt into each other and blend to make a good joint.

[JonW]

The problem with PVC solvent cement is that it can't "melt" the wood. Just dried on the surface, it makes a poor bond. The stuff is not structural at all, and requires that the two pieces melt into each other and blend to make a good joint.

OK, good point. So maybe it's best to use something like an epoxy. It's just plain sticky and should bond to both the wood and PVC, I'd think. Maybe I'll roughen the PVC first, with some sand paper.

[spf45]

OK, good point. So maybe it's best to use something like an epoxy. It's just plain sticky and should bond to both the wood and PVC, I'd think. Maybe I'll roughen the PVC first, with some sand paper.

I think if you have a tight PVC-wood joint, you have set yourself up for success. I would think that if you have a tight fit with the PVC-wood joint, any decent bond from Gorilla or epoxy will suffice. (Heck, bubble gum might take care of that tight joint.) It isn't going to be subject to any stress, right? It's just holding the port in place and keep it from vibrating. With a tight fit, the Gorilla Glue will expand and it's not going to move again. I, personally, don't see the epoxy coming loose whether it expands or not but I would probably use Gorilla because I have it and it is simpler than epoxy.

I've used the Oatey PVC cement plenty of times. It's a good point that it will not work on wood. I'd say use it sparingly on the PVC-PVC joint, you just need to coat the surfaces with the primer (purple stuff) and then get decent coverage with the cement. Twist the pieces together and you will never get the PVC pieces apart. The primer is nasty stuff, don't smell it too much and don't get any on your hands, as they will be stained purple.

[Tom in SoCal]

Jon,
I have done precisely what you are attempting to do and had good results with "liquid Nails" subfloor adhesive.

Tom