Fibreglassing - a Dumb Question

[dankilb]

Can I put the layers of cloth over the bars before the fillets have cured, or must I wait for them to go off?

If anything, this is better as you get a chemical bond between the fillets and the laminate. However, you’ll want to let the fillets set-up/gel a bit, just so you don’t deform them while laying up and (especially) rolling the glass.

 

[dankilb]

Bear in mind the timber may want to absorb a lot of resin (to the point it may dry out your laminate). Suggest careful priming with epoxy (maybe even warmed up to aid viscosity - or at least keep the lot, timber and resin, indoors in the warm beforehand).

 

[Stemar]

Bear in mind the timber may want to absorb a lot of resin (to the point it may dry out your laminate). Suggest careful priming with epoxy (maybe even warmed up to aid viscosity - or at least keep the lot, timber and resin, indoors in the warm beforehand).

Did that yesterday. A quick wipe down with acetone and they should be good to go.

 

[geem]

Thanks, everyone.

The layup is done, with a 20w halogen light on it to help it cure overnight - I'd have liked more, but couldn't find the right kind of bulb. Next step is to do a couple of reinforcing bars in 30 x20mm pressure treated timber, with a few layers of glass cloth over them. I've rounded the top edges to help the cloth fit nicely and coated them with epoxy to help with adhesion. Tomorrow, I plan to fit them and build fillets in the same thickened epoxy I'm going to use to and stick them down. The weather's looking kind to dumb epoxiers again tomorrow, but then it turns a good bit colder, so I'd like to get everything done tomorrow, so dumb question no. 2 is, Can I put the layers of cloth over the bars before the fillets have cured, or must I wait for them to go off? Appearance is unimportant, but structural integrity is. Dumb question, no 3 is, How many layers?

We have added stringers to our dinghy to stiffen the floor. To keep weight down we used pipe insulation cut in half. The strength comes from the shape of the glass rather than the core. You glue the pipe insulation in place with some thickened epoxy and wrap pre wetted glass over the stringers to the required thickness. Thin glass cloth is easiest as it will follow the shape. Thick cloth won't.

 

[Stemar]

Well, it's done.

Before


After


And there's no movement in the skeg now.

Thanks for your help, everyone

 

[Spirit (of Glenans)]

An American boat builder friend taught me to laminate. He told me a story that when they were building high spec carbon epoxy skiffs the cost of acetone was crazy and they bought it in 50gallon drums. They found out that white rum was just as effective so bought a drum of that as it was cheaper than acetone ?

In that case, wouldn't isopropyl alcohol do the job?

 

[geem]

In that case, wouldn't isopropyl alcohol do the job?

No idea. Worth a try but is it cheaper than acetone?

 

[coopec]

No idea. Worth a try but is it cheaper than acetone?

In Australia Acetone is $17.95/L and isopropyl alcohol is $19.95/L

 

[Poignard]

Well, it's done.

Before
View attachment 126136

After
View attachment 126137

And there's no movement in the skeg now.

Thanks for your help, everyone

Good work, and you didn't hang about doing it. Less than a week since you first asked for advice.

 

[Stemar]

I had a weather window - warm enough for the epoxy to go off, and that wasn't going to last, not in November. Today was 5 deg colder, so I'm glad I didn't have to wait for weekends!