What glue?

[Karle Woodward]

I'm gluing a plaque (raw plywood back) to a painted surface. What glue should I use? Will regular woodglue work? Superglue? What do you think?

Thanks,
Karle

[Lee Schierer]

You will need to rough up the painted surface with some 150 or 80 grit sandpaper to give the glue some bite. Regular yellow wood glue will work, but will take a while to dry. You can also use epoxy or urethane glue. Super glue will not hold unless the surfaces are perfectly flat and there are no gaps. If you use urethane glue, use a small amount and stay back a ways from the edges as it will tend to foam. Lightly dampen the plywood and leave it set for 5 minutes or so before you apply the glue. It only takes a very slight amount of moisture to trigger the cure. Let it set over night, but keep an eye on it to clean up any foam out before it sets up completely.

Depending upon the type of paint you may or may not get good adhesion, so I wouldn't recommend relying on the bond if the piece being applied is valuable.

[Rich Engelhardt]

Hello,
What I use isn't glue.
I coat the raw wood with a coat of primer paint.
When that dries, I apply a coat of paint that matches the already painted surface to it - and while it's still wet, I put the two together and set some weight on top for 24 hours.
Anything that squeezes out can be left since it matches the painted surface.

Edit to add:
If the "strength" of a paint to paint bond is a concern, keep in mind how difficult it is to pry the lid off a paint can that has paint left in the rim. That's metal to metal & also a type of "joint" that an adhesive that's formulated to resist shear isn't designed for.