I glued formica to plywood for my table top.I used contact cement.No problems in 5 years. Also I cut some stall matting rubber for my front passenger to sit on and protect the top of the table.We use the rubber mats on the floor of my 156r as floor mats when the table is in camp.

 

Trust me on this, you don't want to use MDF for your top in a wet enviroment. Water will gain access through some place and it will turn into a mass of wood pulp. There is no practical way to waterproof MDF enough to avoid this. A marine or exterior grade plywood is a much better way to go.

 

agree with fishnut. twice the weight and half the strength and any knick in the finish will introduce water. For backyard use it would be fine. On the river not so much.

 

WARNING: Stupid question to follow...

Is marine plywood impregnated with water-proofing-ness not just coated?

 

WARNING: Stupid question to follow...

Is marine plywood impregnated with water-proofing-ness not just coated?

Marine plywood has no voids in the laminations,the glue is the same as any exterier plywood.So for a table top don't waste money on marine plywood,cover it with uathane spar varnish.

 

WARNING: Stupid question to follow...

Is marine plywood impregnated with water-proofing-ness not just coated?

Among other things the glue is waterproof

 

Ok ixnay on the perfect table blanks that fit over the bays, off to the hardware store to order a sheet of marine plywood.
Thanks for the info.
Any one need a table top?

 

Oh a controversy... Here is what I found on eHow:

Differences in the Marine Plywood Manufacturing Process
Waterproof wood is necessary for marine use since standard plywood grades rot after exposure to moisture. The lumber used in marine plywood differs somewhat from regular plywood. In addition to Douglas fir, spruce and cedar, marine plywood suitable for boat and dock construction is made from long-leaf yellow pine, cypress, western larch, and eucalyptus. The main difference in construction is that the surfaces of the plies are better smoothed so as to reduce the "voids," the micro-spaces in between layers, to tightly adhering joints that do not let destructive moisture in. The adhesive is once again the water-resistant phenol-formaldehyde resin used in exterior-grade plywood. All parameters of finishing, grinding and cutting are done with closer tolerances than standard plywood, accounting for the very high cost of marine plywood.

 

More information on plywood:

Marine Ply vs Exterior Ply
Marine Plywood and Exterior Plywood have a few minor differences. Both products use the same adhesiveto bind the layers. The biggest differences have to do with the plies. Marine plywood is not supposed to have any voids in the plies where as exterior grade plywood often will have voids within the plies up to 1.5" in diameter. Also, exterior plywood usually has fewer plies than marine grade. This is especially true in CDX grade of plywood. For 3/4" nominal material CDX has 5 plies, ACX has 7 plies and marine plywood has 7-9 plies depending on the manufacturer. I would not recommend using CCA treated plywood for any boating projects. It is almost always CD grade and is VERY heavy because it is sealed with CCA compound. It also is not save to have around food and splinters from treated plywood are toxic. Stick with higher grades of exterior grade or marine plywood for the best results.

FWIW, I work for a lumber yard and I am often asked to get marine plywood for clients. In Colorado it is only available in 3/4" paper coated (the exterior finish is actually a paper product). IT goes for about $100 a sheet compared to about $35 a sheet for ACX.

Dan

Taken from this thread: http://www.mountainbuzz.com/forums/f15/3-4-or-5-8-plywood-35116.html

 

You don't need marine grade plywood for a river table. Ive been a carpenter since I was about 14. That stuff is nasty. Its rough and the splinters cause infections. I wouldn't want to do any food prep on something treated with CCA. Its really only used in conditions where there is constant ground contact.
AC plywood or birch plywood will work just fine. Seal it with a high quality varathane type sealer before you install it on the table frame.

 

I haven't tried it yet (project #347), but I would like to see how the brush on truck bed liner stuff would work on a table top like that. I've seen it at AutoZone before, might be worth a shot but not on MDF. That stuff is only good for interior trim and mouldings.

 

An outfitter friend of mine told me he started coating beaver boards with truck bed goo. Maint interval on his rental boats went from annual with varnish to every three or four years.

 

There is an adhesive I can only find online called Marine Goo. It's the best adhesive I've ever used. I've sealed punctures in rafts with it as well as reattached a bumper to a car.

 

I used a bed liner product called grizzly grip to coat a plywood roof of my truck camper. It is pretty expensive stuff, but seems pretty bomber. I have only had it for a couple months now though.

It is available in lots of colors. Be sure to use in a very well ventilated area.

 

We use 1/2" MDO. It is a plywood that has a paper covering that is water resistant. It is used mostly for outdoor signs, where it has to stand up to the weather. We paint it well, and it has worked great. Much lighter than 3/4 also.

 

Well here it is, pipe leftover from the frame, fittings ordered from buyrailings.com and poached rubber florring from my last job

 

It looks good!.....in my imagination

 

Well here it is, pipe leftover from the frame, fittings ordered from buyrailings.com and poached rubber florring from my last job. and it is marine ply

 

Looks like you got a critter trying to mate to one of your table legs. That is Colotucky!