procainestart
procainestart SuperDork
10/18/23 6:02 p.m.

I picked up some used, heavy-duty tables from a school, which had them outside, they got wet, and the faux-wood laminate is separating at the edges. Not exactly sure what the laminate is -- I guess I'd call it formica?? It's plastic. 

I'm not much of a woodworker and haves failed to find good glue advice -- got a recommendation for wood-to-plastic?

 

triumph7
triumph7 HalfDork
10/18/23 6:27 p.m.

Either MDF or particle board is usually trash if it gets wet.  It swells up and loses strength.  Maybe, maybe you can sand it smooth but not sure it it's worth it.  As far as glue contact cement is common for formica.

jgrewe
jgrewe Dork
10/18/23 7:43 p.m.

Particle board or MDF are two things I classify as "wooden sponge." The best thing to do is replace the entire top if you can. Another option is to brush on some fiberglass resin on the damaged areas and hope for the best.

wae
wae PowerDork
10/18/23 7:53 p.m.

Dad used to get the 5 gallon pails from Wilsonart and Formica back when he had the cabinet store.  Those could be loaded up into a spray gun and you'd shoot both bits than stick it together.  Recently, we were making a top and all the old pails had dried out, so we brushed on regular Weldwood contact cement.  Watch out for sources of ignition with that stuff and wear your respirator.  Get both bits completely covered, let them dry until they're tacky, and then press them together and keep them clamped or under weight for a day or so.

But, as was stated above, once MDF gets wet it's basically trashed.  It's just a bunch of sawdust pressed together with some fairly weak binders so it will stretch out like a sponge when it absorbs water - and absorb it will! - and it breaks free of the binders.  That said, though, the laminate is going to have some flex to it, so you might be able to get it stuck back on to whatever shape the MDF has taken.  I'd use a bunch of clamps and some narrow bits of wood to try to clamp it back together while following its new contour.

procainestart
procainestart SuperDork
10/19/23 2:53 p.m.

I'll pick up some Weldwood; thanks. 

There are four tables, 48x30. Each tabletop probably weighs ~30-40 lbs?? Surprisingly heavy. The MDF has swollen a little on several, but they aren't completely wrecked. They don't need to be pretty/perfect, and they were free, so I'm just going to splooge Weldwood under the curled edges, stack them on top of each other, and throw a few bags of Sakrete on top to "clamp" them. One table is undamaged and will go on top. 

If it doesn't work, I'll replace them. 75% of why I picked them up is because the bases have a clever chain-and-gear system to raise/lower about 18" by spinning an exposed hex on either side of the tabletop. Takes seconds with a drill.

SV reX
SV reX MegaDork
10/19/23 3:05 p.m.

In reply to procainestart :

Contact cement is the right answer, but maybe not for a small repair. 
 

The way contact cement works is that you actually apply it to both surfaces, let them both dry, then stick them together dry.  If you are thinking of "splooging" some in the crack and hoping it will glue them together, that's not quite the way it works. 
 

Im gonna suggest some strong construction adhesive like Locktite PL3.  It works better for "splooging". 

procainestart
procainestart SuperDork
10/19/23 4:49 p.m.

In reply to SV reX :

Got it; thanks. There's not enough room between surfaces, hence splooge approach. I'll pivot to a construction adhesive. 

glueguy (Forum Supporter)
glueguy (Forum Supporter) GRM+ Memberand Dork
10/19/23 5:01 p.m.

All of the answers have been correct so far

1.  MDF / particle board don't recover well from a lot of water

2. Contact cement is the right adhesive for this.  It works by film strength - coat both sides/dry/press together

3. Aside from that, Weldwood wood glue is most likely to have success.  It applies wet and gets clamped until it dries.

 

 

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