How to fix bubbles in 1708

[GSX455]

I tabbed with 1708 and it wet out great, I put 1 layer of CSM with isophthalic resin, let it cure. Came back today wiped the area with acetone, put 2nd layer of CSM followed by 1708. Had a few spots not wet out, white areas. Other areas were fine. It was warm out so the acetone flash off was complete. I rolled it out some more with a short nap roller, maybe try fiberglass rollers? Would it wet out better, maybe follow up in the evening so the acetone seeps into the cured polyester?

2nd question, the plywood stringer is glued 3/4" pieces (1.5" thick) and is about 1 foot shorter than the original stringer (see photo for original). Should cut out a notch and lengthen the stringer 1.5 feet. I realize a butt joint would offer no strength, but if I cut a 6" long notch and added 1.5 feet of 3/4" plywood it would be the same as the original length.

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[kcassells]

Wrong on the butt joint it is all strength.

if the white spots are bigger than a dime then grind out and relay some new glass. You have to always sand out the glass then acetone then apply glass.
Looking good!
You should try to keep all your questions in your original thread.

 

[tpenfield]

You need to pre-soak the underside of the 1708 in resin first and also wet out the surface you are laying up. It sounds like the way you are wetting out the cloth is trapping air. Yes, a resin roller is a must. A nap roller will just make a mess . . . as you now know.

 

[GSX455]

Thanks for the advice, fiber glass rollers on order, and epoxy for the stringer butt joint. Since it is epoxy I can use 17 ounce bi-axial cloth instead of CSM/1708?

 

[tpenfield]

Sure . . . As long as you get to the desired thickness

 

[kcassells]

You'll be much happier applying the 1700. After the other you won't have bubble problems as much.
You will need to hang out with it while it sets up and work it.
For the patches just precut pcs, one bigger than the next and layer each one, then the next until you get the thickness. The
process is called wetonwet.

 

[kcassells]

Oh yea, make sure the area you remove the bubble from has a slight bevel. That makes the 1700 lay better and lets air out easier.

 

[jynxbone6986]

I used a scarf joint to make my stringers from ply. PL glue to join them. I had to make a jig for it and u need a router but it worked great for me. I tryed breaking a piece that i trimmed off afterward and it wouldnt break at the joint. It snapped at the solid plwood instead. I believe it was a 1:10 angle

 

[Woodonglass]

It is very important to apply a heavy coat of resin to the bare plywood prior to laying the fiberglass cloth. For stringers it's also very important to ensure the plywood edges are saturated with resin and covered with glass. If you do this correctly your grandkids will be able to enjoy this boat.