Fiberglass resin, primer and paint questions

[Johnny M]

Does anyone here know if the fiberglass resins used in the early 70's Boler's were polyester based or were they epoxy based?

Reason I ask is I am building a custom wet bath in ours and the question arose today as if I should use polyester or epoxy resin. I was told the epoxy would bind better to the wood in the wetbath, but would not work with matte as it could delaminate and to use cloth. Several questions were also raised as to the compatibility of primers with the polyester vs epoxy and if one resin would bind to the other existing resin if using two different ones.

Then there was also the question of epoxy paint vs urethane paint for the final top coat of the wetbath. Urethane is suppose to have the best UV resisting properties as well as colorfastness. I have considered using the epoxy based primer and paint for garage floors sold at the big box stores as epoxy is suppose to bind to just about anything and the garage floor epoxy paint certainly is a lot more cost effective.

Also considered using just a modified alkyd oil based top coat and primer instead of the epoxy or urethane paint/primers.

So many questions and not sure which direction to go with...

[VB_in_BC]

Others here could probably confirm but I'm fairly certain Bolers, Trilliums, and similar trailers used polyester resin, due to cost compared with epoxy. I chose epoxy for my trailer repairs. Lots of good info here on using it:

Epoxy by the Leading Epoxy Manufacturer | WEST SYSTEM Epoxy

I agree about using fiberglass cloth, not mat, with epoxy. The mat has a binder that won't dissolve in epoxy resin.

For paint, marine topcoats seem to be a popular choice. Many here have used Interlux Brightside or Rustoleum Topside. I used the Rustoleum and am very happy with the results.

[Johnny M]

Originally Posted by VB_in_BC

Others here could probably confirm but I'm fairly certain Bolers, Trilliums, and similar trailers used polyester resin, due to cost compared with epoxy. I chose epoxy for my trailer repairs. Lots of good info here on using it:

Epoxy by the Leading Epoxy Manufacturer | WEST SYSTEM Epoxy

I agree about using fiberglass cloth, not mat, with epoxy. The mat has a binder that won't dissolve in epoxy resin.

For paint, marine topcoats seem to be a popular choice. Many here have used Interlux Brightside or Rustoleum Topside. I used the Rustoleum and am very happy with the results.

Thanks I will check that link out. Being this is for the wetbath my main concern with resin, primer and top coat is water penetration and delamination

[D White]

Originally Posted by Johnny M

Does anyone here know if the fiberglass resins used in the early 70's Boler's were polyester based or were they epoxy based?

Reason I ask is I am building a custom wet bath in ours and the question arose today as if I should use polyester or epoxy resin. I was told the epoxy would bind better to the wood in the wetbath, but would not work with matte as it could delaminate and to use cloth. Several questions were also raised as to the compatibility of primers with the polyester vs epoxy and if one resin would bind to the other existing resin if using two different ones.

Then there was also the question of epoxy paint vs urethane paint for the final top coat of the wetbath. Urethane is suppose to have the best UV resisting properties as well as colorfastness. I have considered using the epoxy based primer and paint for garage floors sold at the big box stores as epoxy is suppose to bind to just about anything and the garage floor epoxy paint certainly is a lot more cost effective.

Also considered using just a modified alkyd oil based top coat and primer instead of the epoxy or urethane paint/primers.

So many questions and not sure which direction to go with...

Epoxy was never used on Bolers or any other trailer in the 70's and it isn't used on any that I know of now. Epoxy is for boats. You don't need or want it anywhere on your trailer. You don't get delamination or water penetration on your trailer exterior do you??? Water penetration is also only a problem for boats. I would build it out of Polyester mat, not cloth and then prime and paint with which finish system you choose. I would personally use bondo, polyester high build primer, epoxy sealer and then epoxy tub paint...all properly prepared before application of each step and using all safety precautions. Good luck on how ever you choose to do it...you can do it!!!
Fiberglass Dave

[Johnny M]

Thanks Fiberglass Dave! You are just the person who I was hoping would respond to this thread, glad to see you are still on this forum . Your expert advice here is highly valued by myself and many others.

That is what I am gonna do then. I will post pics of the process maybe it will be useful to others also.

[J Ron]

Boats are made of polester resin, epoxy too expensive. New polester will not adhere to cured poly. epoxy will adhere to cured poly. and most anything else. Read the West System info. that was mentioned earlier. We have lived aboard a fiberglass boat for years. FRP, fiberglass reinforced plastic systems are the same where ever they are used. Polisher and epoxy are plastics and very weak unless reinforcement is added such as fiberglss. Interlux Brightside is my paint of choice unless you are a pro painter. Ron

[D White]

Originally Posted by J Ron

Boats are made of polester resin, epoxy too expensive. New polester will not adhere to cured poly. epoxy will adhere to cured poly. and most anything else. Read the West System info. that was mentioned earlier. We have lived aboard a fiberglass boat for years. FRP, fiberglass reinforced plastic systems are the same where ever they are used. Polisher and epoxy are plastics and very weak unless reinforcement is added such as fiberglss. Interlux Brightside is my paint of choice unless you are a pro painter. Ron

This notion that polyester does not stick to polyester and that you must use epoxy is a total lie that has been perpetuated by the West people and other epoxy repair boat people. ARGUING THIS FACT is why I don't post here anymore. We have been fixing fiberglass with fiberglass for 40 years...SO PEOPLE YOU CAN MAKE A LIFELONG REPAIR TO YOUR TRAILER WITH READILY AVAILABLE FIBERGLASS MATERIALS. YOU CAN'T NECESSARILY MAKE A LIFELONG REPAIR TO YOUR FIBERGLASS BOAT THE SAME WAY. Please try it with fiberglass and not let statements like above scare you away from trying it. If it doesn't work the way you wanted, grind it away and try it until it does. IT WILL STICK. You can do it....Fiberglass Dave

[Mike Magee]

I wouldn't worry much about UV resistance for the interior. I mean, it wouldn't be at the top of my priority list.