Epoxy experts - quick question

[lakelover]

What's the best way to apply resin (without cloth) to wood for waterproofing? I got some of the US Composites 635 resin with the 1:3 hardener.

Any other tips?

Thanks.

 

[Bob_VT]

Re: Epoxy experts - quick question

It could be painted on but w/o cloth it will not last

You could at least muster up a single layer of cloth and you will be better off.

I don't believe anyone will tell you to use it straight (alone).

Are you working on the deck or transom?

 

[lakelover]

Re: Epoxy experts - quick question

Are you working on the deck or transom?

The transom at the moment.

 

[BigBoatinOkie]

Re: Epoxy experts - quick question

It would probably help if you stirred in a little milled glass. If you're working on the transom, I'd sure put on some fiberglass though.

 

[lakelover]

Re: Epoxy experts - quick question

Here's something I don't understand. My father-in-law worked for years producing epoxy items, even had government contracts, and working with resins; he often coated wood with resin and it is still around and in GC 25 years later...even outdoors in the north country weather. I haven't consulted with him on this....

If the cloth isn't needed for strength, what is its benefit? Why do you say it won't last as long without it? I thought I would paint it w/ marine paint afterward for UV protection. I could be persuaded that it's necessary, but I need convincing evidence.

P.S. Bob--your signature got topsy turvy!!

 

[Lrider]

Re: Epoxy experts - quick question

If you are working on the transom I would think added strength wouldn't hurt

As to why cloth or fibers, the resin does not stick to the wood very easily, especially hard woods. There are many types of resins for various purposes some are very flexible while others are like glass, I have used resins to cover table tops for years, but they are not work surfaces like a transom.

To make it short the resin needs something to bond to besides the wood to hold it together

 

[andgott]

Re: Epoxy experts - quick question

I too am curious as to why people seem to think that fiberglass cloth is required- Epoxy bonds quite well with dry, properly prepared wood, and a number of manufacturers wouldn't think twice to tell you to do it this way- West Systems, for example, has PLENTY of tech info on their page and in their books about this very application.

In a transom, the FG cloth would help by adding some strength, but there are tons of applications in boatbuilding where epoxy is used without any sort of reinforcement as a waterproofer/sealer or glue for plywood, or solid wood.

 

[bananaboater]

Re: Epoxy experts - quick question

I too am curious as to why people seem to think that fiberglass cloth is required- Epoxy bonds quite well with dry, properly prepared wood, and a number of manufacturers wouldn't think twice to tell you to do it this way- West Systems, for example, has PLENTY of tech info on their page and in their books about this very application.

In a transom, the FG cloth would help by adding some strength, but there are tons of applications in boatbuilding where epoxy is used without any sort of reinforcement as a waterproofer/sealer or glue for plywood, or solid wood.

What he said. With all those layers of ply (1.5") the cloth would provide only a fraction of the wood's strength. On my decking I did 2 layers of epoxy sealing (sanded between) and it worked fine.

 

[lakelover]

Re: Epoxy experts - quick question

I too am curious as to why people seem to think that fiberglass cloth is required- Epoxy bonds quite well with dry, properly prepared wood, and a number of manufacturers wouldn't think twice to tell you to do it this way- West Systems, for example, has PLENTY of tech info on their page and in their books about this very application.

In a transom, the FG cloth would help by adding some strength, but there are tons of applications in boatbuilding where epoxy is used without any sort of reinforcement as a waterproofer/sealer or glue for plywood, or solid wood.

Agreed, and bananaboater makes a good point too. With 1-1/2" of exterior plywood bonded with gorilla glue & SS screws, and the three knee braces on my boat, I think that transom will be as solid as anything in the original design. I seriously think this transom isn't going anywhere it shouldn't with a 50 on it, and how much difference would a layer of glass make?...

Anyway, to get back to my original question, what's best...roller? spreader, or is that just for cloth application?

 

[Doug N.]

Re: Epoxy experts - quick question

I use plastic spreaders like the ones used for Bondo. Since I am a cheapo, I started using key cards that you get at a hotel or motel. Just pitch them out when you are done. A roller soaks up too much epoxy.

My plywood boats soaked up the epoxy just fine. Make sure the plywood is dry so you don't trap moisture. If moisture tries to get out later it will crack the epoxy surface. If you apply the epoxy in the late afternoon, when the wood cools it will do even better drawing in the epoxy.

 

[lakelover]

Re: Epoxy experts - quick question

I use plastic spreaders like the ones used for Bondo. Since I am a cheapo, I started using key cards that you get at a hotel or motel. Just pitch them out when you are done. A roller soaks up too much epoxy.

My plywood boats soaked up the epoxy just fine. Make sure the plywood is dry so you don't trap moisture. If moisture tries to get out later it will crack the epoxy surface. If you apply the epoxy in the late afternoon, when the wood cools it will do even better drawing in the epoxy.

Makes sense, thanks for the tips. Wood is definitely dry, I put it together about a month ago and it's been sitting on my back porch, which can get pretty hot. I hadn't thought about how much epoxy a roller would soak up.

 

[BigBoatinOkie]

Re: Epoxy experts - quick question

I agree that epoxy resin is fine on wood without fiberglass. Since you said you were working on the transom, I was assuming it was a structural piece that would benefit from the strength of fiberglass, and I didn't know what kind of boat you had, or what kind of drive. I know I wouldn't suggest building a non-fiberglassed transom to someone working on an I/O boat. I also think that folks that are used to using poly resins prpbably know how the poly tends to crack a lot if not using glass. Now, I dont' know what kind of wood you are using, but I don't think it's good to put resin on treated wood, but if it's good and dry, it may be okay. Anywho, I like using the little 6" white foam rollers personally.

 

[lakelover]

Re: Epoxy experts - quick question

Thanks, BigBoatinOkie. I agree, when you need the strength, adding cloth is the way to go, but why add work when it's not necessary? (one of my guiding philosophies in life). I did a lot of reading and saw that poly tends to crack without glass, so that's why I decided to spend a little more and get the epoxy.

 

[BigBoatinOkie]

Re: Epoxy experts - quick question

I'm an epoxy man myself.

 

[Doug N.]

Re: Epoxy experts - quick question

Also, small disposable paint brushes work to get into the corners. Don't use the foam ones, they fall apart.

 

[BigBoatinOkie]

Re: Epoxy experts - quick question

I've just glassed a new transom, partial stringers, and deck using 6" foam rollers the whole time, and the only roller that fell apart was one I was cramming into tight corners. I've probably used 20 of those on my project without any problem, except for the one I was way too hard on.

 

[Doug N.]

Re: Epoxy experts - quick question

I meant the foam brushes, not the rollers. I'm sure the foam rollers work fine for a bigger area. I thought even the foam rollers would soak up too much resin, but I guess they worked out OK for you.

 

[BigBoatinOkie]

Re: Epoxy experts - quick question

Yeah, they do soak up quite a bit of resin initially, but as you run out of resin in your batch, you can just apply a little pressure to the roller and squish most of it back out. I don't like to waste high dollar epoxy either. And yes, the foam brushes suck.

 

[ghamby]

Re: Epoxy experts - quick question

I like the West System brand yellow foam rollers. They're designed for epoxy.
They don't fall apart. The gray foam brushes work well for tipping and tight
quarters. GH