I need to glue some 1" square 3/4" plywood blocks to the underside of a styrene plastic turn table pit. The plastic surface has been painted with Floquil rattle can paint. The wood is unfinished. What kind of glue will provide a strong bond?
Epoxy for sure. In actual fact, the bond will be no stronger than the bond between the paint and the plastic. But epoxy will bond to the paint and the wood, no sweat. Alternates. latex caulking compound, or Walther’s Goo. Not so strong, cellulose cement, or white glue.
Is there going to be any stress applied to the bond? If it just needs to sit there, I’d go with something simple like Aileen’s Tacky Glue from a craft store. But, if the bond really needs to hold, then you should sand off the paint and use a CA (superglue) adhesive.
If you decide to use CA, I recommend, ZAP-A-GAP, Medium CA+. I use it all the time, for balsa wood to Plasic buildings with great results, also has a stronger bond, than just any CA, also thicker.
Frank
The most important thing you can do is strip the paint from the plastic surface. Then I would use medium viscosity CA (I like the Sinbad variety) if the bond does not need to be that strong. If strength is needed, go with epoxy.
I would sand or scrape as much paint off the plastic as you could first.
A trick I learned for gluing wood to plastic was to first coat the wood surface with CA and let it dry. This seals the wood fibers. Then use CA to make the actual bond between the two pieces.
The first coat seals the wood preventing it from drawing the glue away from the joint when the second coat is applied. You will be hard pressed to break this joint easily !
Mark.
Interesting technique, Mark. I never thought of that, although I always seal wood with an acrylic sealant prior to painting. I bet using the sealant prior to gluing would work just as well. My recommendation for the medium viscosity CA is to keep it from getting sucked into the wood.
First remove the paint from the contact areas, then use contact cement, and follow the instructions on the container.
Any glue or cement which will stick to paint will likely form a bond stronger than that of the paint to the plastic, and you’re simply altering the point at which the joint will fail.Epoxy forms a poor bond with plastic unless there’s also a mechanical connection, such as interlocking surfaces - I always mix epoxy on a plastic surface, as once it hardens, the excess can easily be peeled off and discarded.
Wayne
Wayne,
Thanks for the contact cement suggestion. For whatever reason I have not used any contact cement in several years so it just didn’t occur to me. After reading your post I bought some contact cement a dnused it very successfully on the subject project. Thanks again!
Some good answers here. But I do have some concerns.
First off, sanding is recommended (as said). A couple of scraps with 60 grit will not only remove the paint, but leave a rough surface which bonds better to most glues/adhesives.
Second, I must ask, why do you need such a strong bond? Is it simply to keep the pit from rotating in the hole? Or do you need this on a portable unit?
If the former, a basic strength flexible glue is what I recommend. (Contact Cement, Rubber Glue, Glue Gun or Latex Caulk) It will be strong enough to hold the pit in place, yet easy enough to peel away for maintenence with a putty knife without breaking it.
I am motorizing a small TT, fabricating my own mount and gearing. The motor is mounted on a short metal bar which, in turn, is mounted on the underside of the TT pit. The motor needs to be approx 3/4" from the pit underside. I had a couple of small pieces of 3/4" plywood at hand so I used them. I didn’t want a screw head visible in the pit so I elected to glue the wood blocks to the underside. And, yes, I did sand off the paint.
Agree with Wayne on using contact cement for a far better and flexible bond. As w/ using the CA (“prime” coat first), the same is true w/ the comtact cement. Coat the wood first and let dry then coat both surfaces and let dry to touch and mount. I found this to be quite important for all the many years of doing plastic (Formica) laminate work. The porous wood can draw a considerable amout of the glue into the grain and cause weak bonding. Pliobond rubber cement is also another excellent choice. It would be applied in the same manner.