MDF glue up question

[rdewinter]

I want to laminate two MDF "pre-primed" boards together using Titebond II yellow glue and screws to make a vertical panel. Would the undercoater on the boards affect the holding power of the yellow glue?

[reible]

How about taking two scraps, glue them together, wait 24 hours and then separate them. Look at the results to see if the primer is a weak spot or not.

I don't know how standard the primers are on this material so even if you get other answers I'd still test what you have.

Ed

[Gene Howe]

Try scuffing with 50-60 grit belt sander on your test pieces.
A light scuff should do the trick.

[charlese]

Both of the above - good recommendations! Another reason to have scrap laying around!

[wa2crk]

Hi;
If memory serves me correctly (and it may not) the yellow carpenter's glue is best suited for bare wood. The glue penetrates into the cellular structure of the wood to provide the bond. Have you thought about a polyurethane type of glue?
Bill V

[pennview]

The primer will affect the bond between the two pieces of MDF -- You'll end up with a paint-to-paint joint, but if your're also screwing the pieces together, it may not make any difference. For a strong glue bond, it needs to be clean MDF. Regardless of what glue or adhesive you use, you'd still end up with paint stuck to paint.

[Stitch]

This might be a question that should be directed at TiteBond; unless someone here is uniquely qualified. I am much too new at this wood working thing to know. For now I will just read and ask questions.

[rdewinter]

Just to close the question on how pre primed MDF would glue up. Well, I used TiteBond II with clamps and the result was a very strong bond. I did glue up the less primed side of the MDF however. Before gluing my project piece, I glued up scrap pieces, clamped and let dry for 15-20 minutes. I clamped the scraps in a vise and used a water pump pliers to break apart. The piece broke but not on the glue line. I am impressed with this woodworking glue.