Paint or Gel Coat Over Epoxy - best way?

[jb93]

I have made bench seats for my aluminum boat and sealed with US Composites epoxy. I have read here on iboats and other places that oil based paints can have issues with drying and adherence when painted directly over epoxy.

Would it be best for me to put on 1 or 2 coats of Spar Urethane over the epoxy, lightly sand, prime and paint with my oil-based Rustoleum as usual...so my primer is adhering to the spar urethane instead of the epoxy?

Lastly....can I do the same process and use gel coat instead of oil based primer and paint...spar urethane over epoxy then gel coat over spar urethane?

Thank you...

 

[bakerjw]

Re: Paint or Gel Coat Over Epoxy - best way?

I think that it's always best to use a primer. WoodOnGlass is a proponent of using the Rustoleum (Majic) paints that are available at Tractor Supply. I'm going to be using epoxy on the deck of my restoration and all I plan on doing is sand the surface, clean it real good with acetone and prime it before painting it.

 

[jigngrub]

Re: Paint or Gel Coat Over Epoxy - best way?

No gel coat on epoxy, gel coat on polyester resin only!

Gel coat does not bond well to epoxy... if at all.

 

[jb93]

Re: Paint or Gel Coat Over Epoxy - best way?

I think that it's always best to use a primer. WoodOnGlass is a proponent of using the Rustoleum (Majic) paints that are available at Tractor Supply. I'm going to be using epoxy on the deck of my restoration and all I plan on doing is sand the surface, clean it real good with acetone and prime it before painting it.

I'm onboard with WOG's method. Painted my aluminum boat his recommended way and very happy with it. I just have been reading that oil based paints over epoxy could have mixed end results. Got me to wondering if putting a coat of spar over the epoxy would improve paint adherence or not necessary. I just don't want my bench seats to start peeling after all the work I have put into them.

 

[jb93]

Re: Paint or Gel Coat Over Epoxy - best way?

No gel coat on epoxy, gel coat on polyester resin only!

Gel coat does not bond well to epoxy... if at all.

I understand that part. If I put spar on top of the epoxy then will gel coat bond to the spar and I am good? Sorry my original question must not be as clear as I thought it was.

 

[Woodonglass]

Re: Paint or Gel Coat Over Epoxy - best way?

No, Gelcoat will not adhere to the spar varnish. It is a Poly based product and only likes to adhere to other poly based products, i.e. polyester or vinylester resin. If you scuff the epoxy with 120 grit and wipe down with Acetone then use the Rustoleum or Majic Metal primer (it works on resin too) you should have excellent results with your paint adhering . I would not Paint until the epoxy was fully cured. i.e. at least a week after application.

 

[pauloman]

Re: Paint or Gel Coat Over Epoxy - best way?

Edit: links to personal webpage

 

[jigngrub]

Re: Paint or Gel Coat Over Epoxy - best way?

I think I'd go with a product like Durabak instead of paint or gel coat:

Non-slip Safety Coating for Your Boat or Ship

 

[ondarvr]

Re: Paint or Gel Coat Over Epoxy - best way?

Also folks with big $$$ buy boats and immediately have the gel coat removed - not good stuff long term.

Paul Oman - MS. MBA
A.K.A. “Professor E. Poxy”
Internet Epoxy Confederation (IEC) Homepage
epoxies since 1994
Member: NACE (National Assoc. of Corrosion Engineers) -- SSPC (Soc. of Protective Coatings)

Paul

You have made this statement many times but have never backed it up with any examples, and I have asked you to frequently.

I deal with several mega yacht builders, not once has any of them removed the gel coat from a new hull to apply another coating. I'm sure at some time somebody has, but it isn't a common practice. Gel coat is rarely the failure point in a polyester hull, it is typically the laminate that blisters, so removing the gel coat does nothing to help the issue.

I have customers that use gel coat as the finish, I have customers that paint over the gel goat, and I have customers that use no gel coat at all, none remove it though.

 

[jb93]

Re: Paint or Gel Coat Over Epoxy - best way?

No, Gelcoat will not adhere to the spar varnish. It is a Poly based product and only likes to adhere to other poly based products, i.e. polyester or vinylester resin. If you scuff the epoxy with 120 grit and wipe down with Acetone then use the Rustoleum or Majic Metal primer (it works on resin too) you should have excellent results with your paint adhering . I would not Paint until the epoxy was fully cured. i.e. at least a week after application.

Thank you for the advice on letting the epoxy fully cure before painting. However, I am a little confused as gel coat is a polyester based product. That is why I thought it would be possible to apply spar over the epoxy and then gelcoat. I feel confident that I will be fine doing the Majic/Rustoleum prime and paint as you suggested, and I will likely just do that. I was just hoping to get a final answer on the idea of spar over epoxy then gel coat over the spar.

 

[Georgesalmon]

Re: Paint or Gel Coat Over Epoxy - best way?

the final answer is that gel coat is nothing more than polyester resin with color, thixotropic agents, and UV protectants + some secret stuff because each manufacturers is the "best". It will not do well over varnish. And its almost never vinylester resin cause vinlyester does not like UV and can't stand the sun.