Does MDF Move?

[kwoodhands]

Dave, quality countertops are laminated on both sides. You may notice on the underside of these tops the dark choclate color. If you look hard you will see this is a very thin lamination of backing paper. Comes in large rolls, glued with contact cement same as laminate that shows. That being said, any good sealer will work,shellac, varnish etc.A counter top that is only laminated on one side has a great chance of looking like a banana in a few days.I once installed a L shaped top like this. I got it flat with clamps and braces from upper cabinets.Screwed well from bottom, looked good when I was done. Went back next week to remove and trash tops. The tops pulled the corner blocking out of the base cabinets.Got a new supplier that day. mike

[kwoodhands]

James, why do you have to trim the laminate?Reglue the laminate. If you used contact cement that is solvent based, take it outside, place a wide blade putty knife under the laminate. Then squirt laquer thinner under laminate, pry gently with knife. Work the knife and laquer thinner in until you either remove entire piece or enough to add more contact onto mdf base and laminate.Pro it open for 20 or 30 minutes or until cement is dry to the touch.Then roll out . Let excess cement if there is any dry. Then you can roll most of it off with your hand and clean remainder with laquer thinner. Laquer thinner and cement are highly flammable, use precautions. mike

[kwoodhands]

James, why do you have to trim the laminate?Reglue the laminate. If you used contact cement that is solvent based, take it outside, place a wide blade putty knife under the laminate. Then squirt laquer thinner under laminate, pry gently with knife. Work the knife and laquer thinner in until you either remove entire piece or enough to add more contact onto mdf base and laminate.Pro it open for 20 or 30 minutes or until cement is dry to the touch.Then roll out . Let excess cement if there is any dry. Then you can roll most of it off with your hand and clean remainder with laquer thinner. Laquer thinner and cement are highly flammable, use precautions. mike

[James "Cubby" Culbertson]

Thanks folks for all the great help! I found the can of the glue that I used and it looks like it is in fact solvent based, not water based as I remembered. I remember debating a lot on which one to use and finally broke down and used the solvent based. It is Hybond 80 Plus. Anyway, got to looking at the table a bit more and realized it's not just the edge that's lifting. I can feel pockets other areas that are lifting as well so the diagnosis that the glue up was the culprit appears to be correct. With the advice of how to remove it, I think I can get the old off and re-do this thing. I'd really like to do this as this was my first project that I did all the mortise/tenons/box joints, etc... by hand. It was actually a lot of fun chopping mortises with a mallet and chisel (not so fun in Hard Maple though!) and I'd hate to have to completely remake the top. I'll give it a try to remove the top and re-glue it. Thanks again folks for the help. Great to know this group has so many good inputs! Cheers, cc

[Phisherman]

[GerryG]

Yes, I'll agree with the others on the glue issue. While most "higher-end" tables do have the bottom surface covered, it's not at all the same issue with plastic as with a wood laminate or veneer. With a wood veneer on top of the MDF, its expansion/contraction will cause considerable stress on the top surface, and needs to be balanced with the same on the bottom. Obviously, plastic laminate doesn't have this issue.

As mentioned, make sure there's a thin coating of contact cement remaining on both surfaces before putting it together. Also as mentioned, the MDF will often absorb most of the first coating of cement. Do not, however, try to get really thick with the contact cement, or you will weaken the joint.

Although the edges of MDF are more porous, normally wood edging is enough. In a laundry, however, I'd seal the edges. Finally, again due to the laundry, I'd also seal the underside with shellac. I've done that in both the kitchen and laundry cabinets and counters. It not only reduces moisture absorbed from the air, but will make it much easier to clean up from any inadvertant spills.

GerryG