Tinting epoxy for inside compartments: mixing ratios

Discussion in 'Boatbuilding' started by Foxwedge, Aug 28, 2021.

  1. Foxwedge
    Joined: Sep 2019
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    Foxwedge Junior Member

    Hi All,
    I am building a John Welsford-designed 'Long Steps'. For these purposes, think SCAMP stretched out.

    So it has various water-tight hatches and storage areas, including a large storage area toward the bow, with two large hatches.

    I think I have decided to coat the interior of these areas with tinted epoxy, for improved moisture and UV resistance. I am thinking a mixture of West barrier coat (mica and aluminum) and titanium dioxide.
    I have already 3 coats neat epoxy over these areas, and would like to get the best protection in fewest subsequent coats. Barrier coat says to mix up to 15% by volume (3 tablespoons to 8oz or 10 pumps). What happens if I exceed that ratio?
    Could I add more for improved uv protection?
    any other tips or thoughts?

    thanks!
     
  2. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    Here are a couple of links to the Long Steps design, for reference.

    Long Steps - John Welsford Designs http://jwboatdesigns.co.nz/plans/long_steps/index.htm

    Long Steps Plans PDF https://duckworks.com/long-steps-pdf/

    I am a bit baffled here - if these areas are inside compartments, then you shouldn't have to worry about UV resistance?
    I would have thought that the 3 coats of epoxy already on the inside of the compartments should be pretty effective at sealing the wood?
    I think that I would keep the barrier coat epoxy for the exterior, below the waterline.
     
  3. Foxwedge
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    Foxwedge Junior Member


    I guess I am taking a belt-and-suspenders approach here. And I need something to lighten them up - too dark.
    Previously, I was planning to epoxy coat and then paint with something. But I like the idea of not needing to grind anything away in the case of a repair, and the tinted coating would be translucent enough to inspect for damage.

    overkill? maybe.
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Certainly the UV aspect internally is not great, I don't know whether epoxy is "friendly" to mildew, I doubt it is, being relatively non-porous, but some pigments do seem to encourage mould, white Titanium seems not to protect against it, but white Zinc seemingly does, so maybe include that in your colourant, it is less opaque as white Titania though, but they can be mixed.
     
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  5. Foxwedge
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    Foxwedge Junior Member

    Thanks,
    That's helpful. Another $27 for a lb of zinc oxide.... I can stomach that, if it means that I can be at peace and return that can of bilgekote....
     
  6. Blueknarr
    Joined: Aug 2017
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    Blueknarr Senior Member

    Adding powder will thicken, reduce opacity and decrease leveling and flow of epoxy.
    Add enough and it gets way lumpy.
    Add way way to much and there won't be enough epoxy to dissolve the powder.
     
  7. Kayakmarathon
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    Kayakmarathon Senior Member

    Do you have enough time and budget to run a test of different material and mix ratio on scrap wood?
     
  8. fallguy
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    fallguy Senior Member

    Nothing is as good as paint.

    That said, I rolled pigmented epoxy on my livewell because I trust it better than paint to not blister.

    Use only dyes formulated as part of part A resin.

    Mix resin by weight and use very little dark pigments, if any, for lockers and wells.

    The UV resistance is not ideal and you can't change that much. The stuff will yellow. And this is why epoxy only is a last resort vs paints.
     
  9. Foxwedge
    Joined: Sep 2019
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    Foxwedge Junior Member

    So, to summarize, you think paint is the best solution here?
    I'm looking to do the "right thing" not a compromise. I didn't want to use a 2-part on the interior and bought a can of Bilgekote. Now I find out they want a 2-part primer first.
    Can someone please just tell me what to do?!?!? I'm getting tired of myself.
     
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  10. fallguy
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    fallguy Senior Member

    I agree. Confusing.

    I used two coats of bilge paint. Myboat is all epoxy. I don't need epoxy primer in a bilge or locker.

    Inside my boat cabin, I used Sherwin Williams one part pre-catalyzed epoxy and man is that stuff special. I will use it in all my lockers from now on. It is hospital wall paint they can scrub all sorts of crap off of..
    12119270-FA9D-4825-BF5F-DFADE5AA0060.jpeg
     
  11. Foxwedge
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    Foxwedge Junior Member

    Fallguy - thanks! I think I'm getting closer to a solution.
    Are you suggesting:
    1) two coats bilgekote, forget the primer
    2) Other bilge paint that doesn't require primer
    0r
    3) sherwin williams epoxy paint (specific product name or code, please??)

    seems like I need to sand between coats of bilgekote. That's obnoxious. I'd prefer something that I can get both coats on without sanding between.

    Returning the Bilgekote seems more and more appealing.
     
  12. fallguy
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    fallguy Senior Member

    I didn't like the bilge paint I bought. I two coated and light sanded between just to knock any glass fibers down. The two coat coverage took too many days to dry and wasn't all that noce when done.

    It was gray and dried kinda slow.

    Any SW dealer will tell you about their pre-catalyzed epoxy hospital paint. I don't recall any uv data on it and don't care. Here is the deal on uv. Epoxy can't handle it. It WILL yellow and chalk in 60 days of direct sun. But these are lockers and paint is tougher than epoxy.

    Get a gallon of precat..you won't regret it. I have it on ceiling, shower walls, cabin interior walls, flat surfaces. Goes on really nice, cleans ez.
     
  13. Foxwedge
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    Foxwedge Junior Member

    Cool, thanks! I like the sound of that. Did you prime the bare eopxy with something first?
     
    Last edited: Aug 29, 2021
  14. fallguy
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    fallguy Senior Member

    No. The precat went on epoxied and faired walls sanded to 120.

    This business of layers of epoxy gets ridiculous after awhile. Understandable for appearance. Annoying for lockers.

    The only thing better would be a paint with uv protection, but many latex house paints with uv are not scrubbable.

    Pro Industrialâ„¢ Pre-Catalyzed Water Based Epoxy - Sherwin-Williams https://www.sherwin-williams.com/painting-contractors/products/pro-industrial-precatalyzed-water-based-epoxy
     

  15. Foxwedge
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    Foxwedge Junior Member

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