Glueing Ethafoam to fiberglass

What’s the best way to glue an ethafoam block (for a seat) to the bottom of a canoe? The canoe is a fiberglass over cedar strip design. The fiberglass is an epoxy base. The canoe is newly constructed at home.

First try the seat before you glue it in. Minicell is generally more comfy for a seat.

Barge cement works well.

Bill H.

contact cement
Minicell is better than Ethafoam and can be shaped better.

The most popular choice is flammable contact cement and the most popular brand is Weldwood by DAP which can be found at most hardware stores in a red and black can.

Don’t do it!
Ethafoam will absorb water and get heavy. If the surfaces that you sit on are not sealed or otherwise finished it will grind you raw.

Get some minicell and glue it with non water soluble Contact cement. (Dap red can)



Ethafoam is closed-cell and will not absorb water. It’s the same stuff used as swimming pool “noodles”.

actually not quite
Here is what Charlie Walbridge says about Ethafoam in his “Boatbuilder’s Manual”: “Ethafoam is a semi-rigid polyethylene foam used extensively by the packaging industry. It is rigid enough for bulkheads and walls, yet flexible enough for padding. Used extensively in outfitting whitewater boats. … Problem: being a ‘semi-closed cell foam’ it will absorb water and get heavy with age.”

Charlie wrote this back in 1982 when minicell foam was not as widely available as today. Ethafoam can be used for a pedestal but minicell is so much superior that you don’t see Ethafoam used much for outfitting these days. It doesn’t shape as well, it isn’t as soft to sit on, and it does absorb some water.

If you already have an Ethafoam pedestal or have made one, I would probably go ahead and try it. You could get a thin 1/4" thick piece of minicell to glue on the top to make it softer. If you decide you don’t like it (and you probably will) you could always take it out and glue in a minicell pedestal. If you don’t yet have a pedestal, by all means go with minicell.

I think Charlie is incorrect. I used

– Last Updated: Jul-12-09 10:47 AM EST –

Ethafoam packing material extensively in canoe pedestals. Saw no indication whatsoever that it was absorbing water, and I carried all my boats on my head. Under close examination, all its cells are closed. Only after sun degrades the surface do those damaged cells take on water.

Disadvantages of Ethafoam compared to Minicell.

1. Coarse cells do not take contact cement as easily. But Ethafoam can be contact-cemented to hulls. Just takes thorough application.

2. Heavier than minicell.

3. Somewhat harder to carve.

4. The black stuff in minicell makes it somewhat UV resistant. Ethafoam degrades quickly at the surface.

Is there some confusion on this point with Styrofoam bead block? Styrofoam does not absorb water, but make a float block from it, and water will creep between the beads.

I too
have used Ethafoam in the past. It’s still used for plenty of kayak bulkheads and I have an older WW K1 that has Ethafoam rather than minicell pillars.

It certainly does not soak up water like a sponge but it retains a damp feel much longer than minicell which can be a bit unpleasant to sit on. I think it is just the very outer layer that absorbs water, and it may well be that not all Ethafoam is created equal.

Bottom line: Ethafoam is usable. Minicell is better.

Yes, water tends to adhere to the
cut cells on the surface of Ethafoam, while it does not do that on Minicell. The finer cell structure on Minicell also makes it contact-cement to itself better than Ethafoam.

Where do you get minicell foam at a decent price?

My Experience

– Last Updated: Jul-12-09 5:54 PM EST –

In the Boston area Ethafoam was used extensively as side flotation before minicell became available. Over several years those boats got heavier and heavier as the foam slowly absorbed water. We're talking 100 lb Penobscotts and 110 lb Trippers here. UHGLY!

The Mowhawk Whitewater that we paddled the Clyde in three weeks ago had the side flotation and kneepads made from the stuff. Fortunatly we could take out the side floatation dropping about 30 lbs off the portage weight. But those kneepads chewed up our knees something awful.

My vote is just say no to ethafoam.


There are many weights of Ethafoam…
…so you can’t make blanket statements about it. It’s available in 1.2#, 2#, 4#, 6# and 9# per cubic foot densities. The lighter weights have very large cells that are poorly separated. They will deteriorate rapidly and absorb a lot of water. The heavier versions have progressively smaller cells and are more durable, but they’re heavy. Minicel is far superior to Ethafoam for kayak use in every regard except price. The reason you see it in cheap boats, pool noodles and such is that it’s cheap. It’s also more difficult to get a good glue bond with it than it is with Minicel.

I haven’'t seen a lot of variance in
minicell prices. Check out:

Now run by Davey and Jennifer Hearn, slalom racers of Maximum Whitewater Performance. See if their prices are a little better than other offerings you’ve seen.

Tommy, surface degradation of
Ethafoam can cause it to hold more water, but it is a thoroughly closed-cell foam, and water will NOT travel into foam cells that have not been cut.

I had a 3 to 4 layer Ethafoam pedestal running through the middle of our Tripper, and while it weighed about 90 pounds when I finished, it never weighed much more than that. When I took the foam out years later, it did not feel waterlogged.

The Ethafoam I saw and used was
relatively small celled. I can see where a cheaper grade with large cells could get spongy from mechanical cell damage.

Ethafoam was a Dow product introduced as

– Last Updated: Jul-13-09 7:29 AM EST –

a superior shock and vibration insulator for use in reusable packaging. Many competitors soon marketed less expensive and generally poorer quality closed-cell polyethylene foam products and experiences with these may have hurt Ethafoam's reputation. People often say "Kleenex" when they mean "facial tissues", and sales people often call inferior foams "Ethafoam".

When protected from UV, it will remain resilient and buoyant indefinitely. When exposed, it tends to degrade rather quickly. Minicel is a better choice, but if you really want to use poly foam, you can "skin" cut surfaces by careful use of a heat gun to seal the cut cells for better contact area for adhesives or just to make the surface feel smoother.


– Last Updated: Jul-13-09 2:03 PM EST –

"In the Boston area Ethafoam was used extensively as side flotation before minicell became available. Over several years those boats got heavier and heavier as the foam slowly absorbed water. We're talking 100 lb Penobscotts and 110 lb Trippers here."

I remember you Boston boaters well. You were experts in that side flotation obsession, which didn't propagate too far outside of Beantown. My peer pressure group in the greater NY area was early obsessed with light weight, even those who couldn't paddle. Hence, we could ferry faster and destroy more boats than the Boston group.

I was very impressed once when a Boston boater demonstrated how side flotation could assist water drainage.

I agree minicell is preferable for all the reasons stated.

3m Spray adhesive
I have used closed cell foam on the seat of every kayak i have ever owned. You can use an electric “turkey” knife to cut it with and bevel the edges to fit the seat pan. 3m spray adhesive or contact cement will work. I like the 3m spray since the foam can be removed if needed. You will destroy the foam but then be able to clean the plastic. I have never had any of the foam come loose using the spray. You can buy foam at Kayak fishing stuff or Austin Kayak. Some local heating and ac vendors or plumbing contractors will typically keep sheets of closed cell foam for pipe insulation. Not to be confused with the preformed pipe insulation everyone carries. One brand is called Rubatex.

Not me Bro
As a newbie I got to lug a few of those behemoths.

I was never nuts enough to paddle them though.

Well… maybe once. Oh the shame!


Another vote for Minicell
2nd for The amazing Barge Cement … night and day better than the typical Ace / Home Depot varieties.

You can try for a good source but make sure you tell them you want it cosmetically perfect.