Polyester resin remains tacky

[Mark Poole ModVP]

Ever seen an old Prather hull? Epoxy glass and full of pin holes. Required hours of fill and sand before paint. Don't know what brand they used but that was very unusual for the 'gas' bubbles to remain against the mold surface. Many life size boats that stay in the water at a marina develop 'blisters'. Mainly the result of poor, high production laminating practices. It's all about workmanship.

 

[Rudy Formanek]

All the epoxy glass products I have dealt with have had pinholes, including Phil Thomas boats, including Bridi fuselages, including Bob Smith fuselages, including Prather Lil Tony, including Prather tunnel hulls, including Prather Monos,. Bob Violet fuselages, are you saying they had poor craftsmanship???

 

[GraysonTaylor]

Now I don't feel so bad about the pinholes in my epoxy covered wood !

 

[Bill Gibson]

I build epoxy resin hand laid chemical tanks for our Piper Aztec mosquito control spray planes.....they get pinholes just like pretty much anything else that is laid up with epoxy resin......I just skim coat the tank with "Icing" and sand it lightly....no big deal! Epoxy is a bit more difficult to work with than polyester, but it is also superior in strength and chemical resistance than polyester resin......ive also built a couple of Phil Thomas hulls........it didn't take hours to fill and sand the pinholes that were in the boat....if you use the right stuff! Ive got nothing against polyester resins, I run a 20 seaducer mono, and im not sure what Jerry uses for his layups, but they sure look nice and hold up well!

 

[Kez]

I use epoxy to lay up tanks trays. radio box and cowlings. I make my own 'gel coat' by mixing colloidal silica with epoxy resin and brush this paste on the mold. After it has partially cured, I start the lay up process. Parts made this way have no pinholes.

I like epoxy and I think it is easier to work with because of the predictable pot life. Polyester resin, however, sets too quickly. So I can only make small batches.

 

[Mark Poole ModVP]

I am saying their resin application process needed rethinking. I have seen some of those boats with so many voids in them I would have returned them.

 

[SayMikey]

The easiest solution is to apply a first coat of epoxy and let it sit til its tacky then start your layup. Problem is its time consuming,I use a clean mold and just go slow

 

[Terry Keeley]

What if you got the bubbles out under vacuum like my props molds?

It's the bubbles that cause pin holes ain't it?

 

[Bill Gibson]

What if you got the bubbles out under vacuum like my props molds?

It's the bubbles that cause pin holes ain't it?

We tried it on an airplane chemical tank, still had the little pinholes...went back to hand layups as it was simply easier and the tank was still super strong