Glass on wood boat question?

[sublauxation]

Hope you don't mind helping with this one......technically it is a boat though! My kid is building a 4ft long RC boat out of Luan plywood. I can include pics tomorrow if it helps. He glued the 2 bottom pieces of hull and the 2 sides together with wood glue and fiberglass applied a coat of fiberglass resin. Everything worked great. He then resigned both sides of the top and used a glue compatible with fiberglass to glue the top to the sides. When he put on the next coat of resin some of the glue let loose along the seem. It almost seems like the resin ate the adhesive.

Would it be possible to just add resin to the opening and clamp them together? Would that hold them together? Any other adhesive that may work?

Also, he applied another coat of resin to the top. He added the hardener but forgot to mix them before applying so after 24 hours most of it didn't dry. He wiped off everything that will come off but it's still tacky. Is there a cure for that? I've read that adding a hot coat of resin could work, how hot would that have to be? Twice the hardener or more?

Any advice is much appreciated.

Thanks.

 

[tpenfield]

resin tends to attack adhesives that are not fully cured.

No real cure for uncured resin. Wipe with acetone to remove the slime and do over.

 

[Scott Danforth]

When i was building RC boats, we would cover the entire model with resin and cloth

 

[sublauxation]

Can the resin itself act like an adhesive to fill in the seam or will it just crack?

 

[Scott Danforth]

If the resin was epoxy, it would work. Poly resin needs glass to have any strength and soesnt work as an adhesive

 

[sheboyganjohn]

Straight resin will not work. If you have some thickener. like cabosil, and then snip up a bunch of small glass fibers, or buy some 1/4" or 1/8" milled fibers, you can make an adhesive that will work. For something the size of an RC boat I would spring on a small batch of epoxy and use that to glue it together. I think even something like JB weld would work in this situation.

 

[sublauxation]

I bought an epoxy type glue, will that possibly stick over the polyester resin or should I look into an epoxy resin?

Most of the polyester resin is dried but what can I do about the tacky areas?

 

[mickyryan]

either use epoxy or poly not both or bad results can happen you can use epoxy on poly but not vice versa, make thickened resin and use that or thicken your epoxy and use that . but once you use epoxy you can no longer use poly and some paints wont work well with epoxy as well without proper prep

 

[Woodonglass]

Epoxy pretty much sticks to anything, Poly...Not so much

 

[sublauxation]

Thanks for the help.

We stuck a 5 minute epoxy into the gap and clamped it shut. It seems to have kept the top tight. My kid scraped/sanded off the wet/tacky poly resin, cleaned it up, and put on another coat of poly resin (mixed up this time).

That dried nicely and he primed it this evening. So far everything seems to be playing nicely together and drying as it should.

The sides have some epoxy that seeped out. He'll sand that smooth tomorrow, and hope for the best as far as top coating that.

 

[sublauxation]

.....he's not happy with the finish as it's not as baby butt smooth as he'd hoped but I keep reminding him that he's built a wood boat from scratch for the first time at age 14 and absolute perfection was an unlikely outcome.

Now to get the engine back in and hopefully it will be on the water for Labor Day!

 

[sheboyganjohn]

If he wants it completely smooth introduce him to high build primer and sanding blocks. When he is sick of sanding he will be half way there.

Here is a good video on what he needs to do, but on a slightly larger scale then what he is doing.

 

[sublauxation]

LOL, I've tried several times to get him to understand that concept that prep is key to this whole thing. It's a lesson he's trying to learn the hard way.

Sunday night we stayed up until almost midnight sanding what was there down to 400 grit, and he was going to shoot color yesterday when he woke up.

He really wants this done and looking good for Labor Day weekend so being a dad I woke up early yesterday, bought a can of high build primer and laid out a couple coats that would dry for him to sand when he woke up. When I finished it actually looked really good.

He was pretty excited when he called after first seeing it, then he called back an hour later after spraying color complaining that the whole finish is nothing but swirl marks. Turns out, despite my advice, he started and finished with 150 grit paper.

Sometimes learning the hard way is best, a little more sanding............and maybe a spray gun for Christmas!