Wooden Boat People
By McKenzieDriftBoat.com
EPOXY vs POLY RESIN TEST RESULTS
Hello all - just finished a couple of tests last night and thought I would share the results.
I used 2 pcs of 2' x 4' of 1/4" plywood.
On 1 pc I just put a coat of poly/iso resin on approx. 1-1/2' of the board
then 1 layer of fiberglass for the next 1-1/2'
then 2 layers of fiberglass for the rest of the length.
I left the back side of each board free of any type of coverage.
On the other piece, I did the same thing but used System 3 Clear Coat Epoxy.
My garage is not heated so I let both pieces "cure" for 10 days, with an avg.
temp. in my garage of 45 - 50 degrees.
Here are the results of the comparison.
Bend test.
I stood both pcs on end and bowed them at the same time with the dbl coverage end at the bottom.
I was able to bend both pcs in to an almost half circle. There was a little cracking noise when both pieces
were at their greatest point of flex, but there was no noticeable cracking or delaminating on either piece.
I was very please with the performance of each.
Impact test.
I started with a 10 lb weight and dropped it on edge from a height of 2' and then 3'
I dropped the weight 3 times from each height, on each board, impacting each different layer of coverage.
With both pieces, I was very pleased with the results. There was not any noticeable cracking or delaminating, nor could I even see any denting in the face or on the back of the boards from where the weight impacted.
Hammer test.
I used a 21 oz framing hammer and beat the crap out of both pieces.
It took a very hard swing until I even started to leave marks in either piece.
But the first to fail was the piece covered with the poly/iso resin and 2 layers of glass.
the failure was on the back side. The glass held, but the plywood behind fractured and
eventually broke completely apart.
As soon as the wood fractured behind the poly/iso the biggest problem became evident.
Delaminating.
As stated on this site before, the adhesion properties of the 2 are VERY different.
Even when the wood broke on the piece covered with epoxy, there was still significant
adhesion the wood, so much so that as I broke the board completely apart, it came apart
with the fiberglass and wood still together but broken into slivers.
With the poly/iso resin, as soon as the wood broke, it almost completely delaminated from the entire piece.
I am curious as to what will happen when I test with fiberglass on both sides????
Final thoughts... As far as working with either the resin or epoxy I was really pleased.
But as anyone who has ever worked with the resins before can attest, As soon as the resin
starts to kick, the smell is VERY intense. Completely drove me out of the garage, even with one of the doors open, and that night, completely overwhelmed my entire house. I had to open both garage doors and leave them open all night.
12 days later, you can still smell it in my house.
Pissed off a couple of my neighbors with the smell the next day as well.... oops.
Much better adhesion/absorption into the pw with epoxy,
didn’t notice much difference between the 2 for brittleness, maybe a little worse with the poly/iso.
Impact resistance was really good on both of them. I really had to beat the crap out of them before any face impact marks started to show. Although the epoxy did hold up better.
The poly smell is HORRIBLE and probably toxic as hell. (Still haven't read all of the warnings yet but I did have help from a person that uses it almost daily and we had full carbon respirators, good gloves and were suited up).
Price - the resin is significantly less $$$$. And right now, for me, that is a big issue.
Overall, I believe the epoxy to be a much better product for my particular project (18' HD), but for this boat I will be using the poly resin, because of the price difference.
BUT - If I ever build another boat, I will definately save up a little extra and use epoxy.
Greg
Views: 592
Replies to This Discussion
-
Permalink Reply by Frank R on
-
I have read that polyester resin absorbs water over time.
Like you said, the difference in price is not worth the trouble.
-
-
Greg/Frank
Polyester does in fact absorb water. One of my former bosses(worth millions) bought a 47' Gulfstar Motor Trauler. He was a Navy WWII vet and loved the water. After a few years the hull developed "blisters" and he had to lay it up for over a year to let it dry out and then get refinished with(I think) epoxy and Aulgrip. Talk about a POed vet. The boat was always in the water at a dock . A drift boat would not be subject to these conditions. You should be fine with poly- hope it dosen't rot out your brain.
Good Luck
-
Permalink Reply by Greg Jensen on
-
Thanks for that... I think lol
-
-
I was finally able to speak with a really good tech rep from the resin comany, and here is a brief update of the information I received.
The most critical aspect of the bond with poly resin and wood is the ambient temp when it is applied. It must be over 60 degrees for best results, the warmer the better.
On my original test, my garage was between 45 - 50 degrees. While the resin did bond, the likely hood for delamination increases because at the colder temps, the resin will not soak into the wood as well.
Also - use 30 or 60 grit sandpaper and HAND sand the wood in one (1) direction. This creates small grooves in the wood and increased the surface area for the resin to bond to. Do not use an orbital or power sander as it will smooth the wood and decrease the surface area for bonding.
I did an additional test piece of 1/4" 2 x 2 plywood, covering each side with one layer of glass, built a small heated inclosure (wood framed, covered with blue insulation board and heated with a 100 watt light bulb).
waited 5 days and then knocked the crap out of it with a hammer.
The results were very rewarding.
In my first test, when impacted hard enough the wood under the glass was shattered and broke apart, this is when the pieces started to delaminate.
With the latest test have glass on both sides of the wood, while eventually the wood core did break, it did NOT delaminate from the resin and glass. and trust me when I say I REALLY had to beat the hell out of it to break it.
I was not able to puncture the glass with the face of the hammer. It wasn't until I placed the sample on the grass and used the claw that I puntured the sample.I was quite please with the results and have a much better peace of mind about my project.
As a side note, I glass the inside bottom of my boat last night and had a wierd side effect of the resin vapors. Apperantly it make me want to cook.... I made brownies, cookies and cooked 6 pieces of chicken.
So if anyone wants to come over and see how resin works on wood, come on over....
I will provide the treats...
Greg
-
Permalink Reply by Guy Fredrickson on
-
Greg, I would like to stop by some time today or this weekend to see your progress. I am expecting a plywood delivery this afternoon (the two additional sheets that I need because I made an ordering mistake with the first order). I will start scarfing the plywood today. Guy
-
-
Guy - I will be doing my final cut and installing my bottom Saturday.
Then sanding and laying glass on the outside hopefully Sat. afternoon.
You are more than welcome to come by.
180 E. 20th Street.
208-220-7996
Hope to see you.
Greg
© 2024 Created by Randy Dersham.
Powered by
