Recommendations on paint over epoxy?

Discussion in 'Fiberglass and Composite Boat Building' started by leaky, Feb 10, 2014.

  1. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    Back in the middle ages, when I ran a boat repair operation, I installed a lot of non skid surfaces. It did not take long to discover that silica was not the best choice. It was, as previously noted above, a ***** to strip. After some experimentation I landed on granulated cork. It was sufficiently durable under top coats and even when exposed it remained suitably non skid. It was also kinder to elbows and knees. In extreme cases, for hard headed owners, I even used bird gravel for a sure thing non skid. I only used it when I believed that I'd never have to strip it.

    At one point in time I built slot car tracks. I used finely ground pumice for the subtle texture on the tracks. My tracks were wildly popular because the traction was superb. The hobby shop owners loved it because they sold a lot of tires. Of course the rubber piled up after a few hours and the tracks needed to be vacuumed. Nascar fans will know about the hazards of "marbles" in the high corners. Same thing on slot car tracks.
     
  2. SukiSolo
    Joined: Dec 2012
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    Location: Hampshire UK

    SukiSolo Senior Member

    So have you tried the pumice as a non skid surface mixed in deck paint?. It is available in 500 grit from jewellry suppliers. I have not tried it myself so I would be interested to hear your experience.
     
  3. rwatson
    Joined: Aug 2007
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    Location: Tasmania,Australia

    rwatson Senior Member

    Yeah - it works great. Apply the pumice on the deck, run a router in two continuous circles around the deck, glue down some copper foil that is used for stained glass windows on each side of the grooves. Then you can wire it up to your house battery.

    Take lots of spare slot cars on a long trip though, a few will go overboard on tight corners.
     
  4. pauloman
    Joined: Jun 2010
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    Location: New Hampshire

    pauloman Epoxy Vendor

    if you don't mind a silver or gray color our aluminum aluthane paint (you can google aluthane and or ask PAR about it) can be applied at temps just above freezing and is abd outstanding primer or topcoat.

    we are located in NH - you might even be able to pick up and save shipping


    Paul Oman - MS. MBA
    A.K.A. “Professor E. Poxy” - “Old Goat” - “Epoxy Guru”
    www.epoxyfacts.com
    www.everything-epoxy.info
    www.epoxyguru.com

    epoxies since 1994
    Member: NACE (National Assoc. of Corrosion Engineers) -- SSPC (Soc. of Protective Coatings)
     
  5. leaky
    Joined: Sep 2008
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    Location: nh

    leaky Senior Member

    Thanks for the help guys! Sorry, I just noticed these latest posts.

    This is what I've been doing; I'm using the water base deck paint for most everything. I got a sandable grit to add when I finish the decks. So far so good on performance - it dries really easy in my basement and yesterday half the tools I own found a way to fall off the gunnel onto a surface painted with it - not a scratch. Only annoyance was during cleanup of 5200, I found acetone easily strips the latex.

    On a couple other parts - like the transom pad that is partially under water, I'm using a single part polyurethane.

    The polyurethane is working fine but giving me some hell as far as dry times go, it dries to the touch within 8 hours but then is not well cured for what I believe is about 48 hours and I'm not sure at that point if I quite want to trample on it. Looking at the Interlux instructions I think that's about inline - they claim @50 degrees 16 hours to cure (add in a little manufacturers exaggeration of fast dry times, humidity in basement, being a bit under 50 degrees etc..)..

    The trouble experienced made my mind on the water based - I figure this way I can at least get my project wrapped up without being bogged down in paint. Then later if I'm unhappy with the water based at least it was cheap and can be removed with the most gentle of paint strippers for an easy re-coat on a 80 degree day in the summer.

    Thanks Paul - you are the guy with the Progressive Epoxy, right? I'm going to keep that in mind but am employing KISS with the water based primer for this project - figuring then if I decide I must use something better I can easily take it back all the way to the resin.

    Jon
     
  6. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Some single part polyurethanes don't cure well (if at all) on an epoxy surface, which is why it's always recommended with these and alkyd paints to use a compatible primer. If you did use an appropriate primer, it's likely just a temperature thing. You have to remember the manufacture's drying times are in a laboratory setting, with perfect humidity, ideal temperatures, etc., so your real world results will be different.

    I'll second the Aluthane paint Paul has suggested, as a tough coating. It can be over coated with whatever, knowing you have a solid base. In fact, I need to order some more, for a trailer I'm rebuilding.
     
  7. pauloman
    Joined: Jun 2010
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    Location: New Hampshire

    pauloman Epoxy Vendor

    as mentioned above - once in a while alkyd enamels have problems going over epoxies with nonyl phenol in them. It is rare - under certain conditions of temp and humidity - only seems to happen here in NH is the worst of summer.

    that said, a nice quick drying pigmented primer is really nice. The color makes everything even and shows spots that need or sanding or whatever.

    I would use aluthane moisture cure urethane as a primer and then oil based enamel from the hardware store.

    If you want to go fancy - a clear 2 part LPU on top. clear is cheaper and doesn't show the user flaws like the pigmented versions. A good way to learn 'roll and tip' application

    Paul Oman - MS. MBA
    A.K.A. “Professor E. Poxy” - “Old Goat” - “Epoxy Guru”
    www.epoxyfacts.com
    www.everything-epoxy.info
    www.epoxyguru.com

    epoxies since 1994
    Member: NACE (National Assoc. of Corrosion Engineers) -- SSPC (Soc. of Protective Coatings)
     
  8. leaky
    Joined: Sep 2008
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    Location: nh

    leaky Senior Member

    Thanks guys - Since I had the polyurethane and only planned on using like a pint on one area, I didn't bother buying primer. Actually it didn't even occur to me until I read a bit more on it that it potentially could have a problem.

    I do very thoroughly wash, sand, then wash again before painting. I will say the Marinepoxy I've been very happy with but seems to blush like nobody's business. Compared to other standard epoxies it has a really nice viscosity and seems to resist the tendency to crystallize in the cold, laminates as well as Silvertip for way less $$, however it seems to be a "high blush" formula ;)..

    What I did do though before even starting was I had blotched some wood with the end of a batch, let it dry, and then without even washing or sanding I put a little paint on both an epoxy and non-epoxy spot. It dried on both in the same unsatisfactory slow (but steady and complete) manner. I did the same thing with the water base paint actually - just have been bit by this so many different times and ways I test everything now.

    I'll put some more thought into what to do with the deck before I go putting paint on. Have just been painting sub-deck & trim parts so far. Sounds like nobody is a fan of the water base :(..

    FYI cosmetics though I simply do not care; I'm not even going to fair any of this when done. It's just a deck that will be covered in blood and scales with any luck come June. What I care about is that it lasts, hence the complete epoxy job over marine ply.

    The simple thing other than water-base is to go to West Marine and get a couple quarts of white Interlux Poly & their primer - it is very reasonably priced with a good Port Supply and after reading more they even recommend it over epoxy and document the process. I could roll the boat out of the tent and burn some kerosene to make an 80+ degree painting booth.

    Jon
     
  9. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Jon, if you use the slow hardener in Marinepoxy, it will not blush unless you're doing the work in the rain.
     
  10. leaky
    Joined: Sep 2008
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    leaky Senior Member

    Oh that's good to know. Water makes blush? Funny, we are also working on a friends lobster boat, just put like 80 square feet down on his new pilot-house roof. It blushed like they write about - during the process I was noticing the snow on the roof of the tent was melting due to the heater and it found a way to drip (not to mention my damn respirator always making me blow condensation on the work).. The resin did cure fine, just a good amount of blush.

    I'm working in temps that are very non ideal so it's all fast dry (and would by extra-fast if they made it) - actually did some layups in as low as 15 degrees. I bring the parts outside to glass them (to keep mess outside) and then move them inside for drying. Basement is 45 degrees, 50 if the furnace keeps cycling, but space is limited in there so other parts curing in the garage that is like 30-40 degrees. I sorta rotate parts around to get them time next to the furnace ;)..

    I'm sure this is on the far end of any reasonable fiberglass layup environment. Epoxy sure is great stuff though - I could never get away with this using polyester!

    Jon
     
  11. SukiSolo
    Joined: Dec 2012
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    Location: Hampshire UK

    SukiSolo Senior Member

    About 4 years ago I was refinishing from bare wood the deck of an OK with one pack poly. Outside was -15 Deg C at night but I could keep about 6-7 in my insulated workshop with no problem. I found that unless the temperature was above 10 Deg C the polyurethane would not cure properly. Once I boosted the temperature up above that point it went off and overcoated fine. That was with Hempel varnish, but I have found International to be similar at least with one pack paints.

    So far maybe I have been lucky but after abrading epoxy and cleaning with acetone and the relevant paint thinner so far I've not had anything not take properly.
     
  12. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Skip the acetone wash after sanding, just wash (a mild soap if you must, but it's not necessary, as blush is water soluble) and dry epoxy, then move on. Anything else runs the risk of contamination.
     
  13. leaky
    Joined: Sep 2008
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    leaky Senior Member

    That's what System III tells you in their documentation.

    Also what I notice is if you really dig into any resin or paint with acetone, it has a tendency to soften them somewhat (even epoxy).

    Slight softening of the resin could even help with bonding of polyester and a polyester gelcoat or something - but that effect seems very contradictory to what you'd want if attempting to paint epoxy (where if anything you want to post-cure it and not make it sticky).

    Jon
     
  14. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    System Three recommends an acetone wash? This is directly against what the other major formulators suggest and what I've found is desirable. You don't want a chemical reaction of some type, taking place within subsequent coats of whatever is going over it. This is just asking for a problem (one of several).

    If the next coating is chemically compatible with epoxy (like more epoxy), you can try to get some kind of chemical bond, while the epoxy is still green. Other wise the only other bond is a well toothed and cured epoxy, that gets over coated. This is strictly a mechanical bond, relying on the physical grip the next coating can get on the epoxy (and why it's heavily scratched).
     

  15. leaky
    Joined: Sep 2008
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    Location: nh

    leaky Senior Member

    No, I was pointing out what you stated is exactly what System III recommends (water wash not acetone).

    Jon
     
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