Gelcoat as non-skid on Deck

Discussion in 'Boatbuilding' started by Klink Sanford, Dec 10, 2021.

  1. Klink Sanford
    Joined: Dec 2021
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    Location: Sanford FL

    Klink Sanford Junior Member

    I want to roller and brush apply gelcoat as non-skid over an epoxied deck that has cured for one year in a barn (out of the sun). I studied all the different advice on the internet, and concluded that it'd be a good idea to test everything on plywood so my mistakes just cost me a little gelcoat and time. So, far I have gotten the pattern method down, I am satisfied with the way the pattern looks. It is finer grain, not the standard initial big pattern you get with a roller. My problem is that the coats are too thin. My first coat is un-thickened gelcoat (I got 4 mils), and my second coat is thickened with Cabosil (I got 14mils). The test panels are under 2 sq ft and the rollers are cut to 3 inches. Because the tests are so small, the roller sucks up all the gelcoat. QUESTION: If I increase the gelcoat quantity for the small test, can one really roll 18mils with a roller and un-thickened gelcoat? Or should I use a brush for un-thickened? On the 2nd coat, the thickened gelcoat, I think I will be Ok by just mixing up more gelcoat to compensate for the roller sucking, so, should I also thicken the first coat with Cabosil?

    I have been using un-waxed gelcoat and using PVA after the final coat. The test samples have all finished a bit sticky, and I think it is because the coats were too thin.
     
  2. ondarvr
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    ondarvr Senior Member

    Don't concern yourself with the how thick a roller applies it, and there's no need to thicken the gel coat.

    The procedure is to apply one coat of gel coat, immediately apply the chosen grit size and type in the amount you feel is correct, wait for that to harden. Apply as many coats of gel coat after that as needed to achieve the actual texture you desire, every additional coat will reduce how aggressive the texture will be.

    You can use either wax or PVA to cure the final coat. When using PVA, as soon as you are done rolling the gel coat immediately apply the PVA.

    Whatever amount of gel coat the roller sucks up is something you need to live with and plan for.

    Make sure the gel coat you are going to use will bond to the exact epoxy used for the deck, not all gel coats and epoxies play well with each other.
     
  3. Klink Sanford
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    Klink Sanford Junior Member

    My concern is that the final product after the two coats remains a tad sticky after applying PVA and letting it sit overnight. I've been told that one cause for stickiness, can be a too thin a coat.

    There is no grit, the texture comes from the roller technique

    I did that, having learned it from another posting of yours, thanks

    Thank you for your kind response.
     
  4. ondarvr
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    ondarvr Senior Member

    The rolling with thickened gel coat works, but will wear down quicker in high traffic areas.

    Thickened gel coat doesn't bond as well as plain gel coat, and resin will bond better than both.

    To enhance the bond to epoxy you could apply a very light coat of resin prior to the thickened gel coat, then apply a coat of regular gel coat over it then PVA.

    Unless the gel coat is old and/or under catalyzed it should cure tack free under PVA. Color can affect it though, white should cure OK, bold colors don't cure as well.

    Temperature and humidity can affect the cure time, high humidity and low temps can extend it a great deal.

    I used to use this method on a particular line of products that needed a deep texture, but also needed to be skin friendly.
     
  5. Klink Sanford
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    Klink Sanford Junior Member

    Didn't know that. I will then put a coat of laminating resin first over the epoxy floor, then unthickened no wax gelcoat, then thickened waxed gelcoat as the final coat. Will allow each coat to dry overnight.

    I'm not having good success with the PVA on these tests because it is too thick to apply with a spray bottle, and so I apply if with a 2" chip brush, and in applying it 8 minutes after I texture the gelcoat with the roller, the brush is smoothing out the PVA. Maybe I can thin it with Iso alcohol or water?

    My color is white

    I'm in Central Florida, humidity this time of year 11am to 6pm is around 60%, not like the summer when it is 100%!!! The temp is like 80 degrees now.

    Once again, thanks for your time.
     
  6. ondarvr
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    ondarvr Senior Member

    Use the unthickend gel coat with wax last, it will cure better than the thickened version. One thing about wax cured gel coat, while hard, it may not become fully cured. The surface can collect dirt, footprints, stains and other things to a greater degree than mold surface gel coat.

    You can add Duratec clear additive and the gel coat and it will cure harder and more thoroughly, resulting in less staining.

    Duratec in the gel coat will give it a glossy finish, Duratec can be used with wax to give a non gloss finish.

    PVA is difficult to apply in an application like this unless it can be sprayed.
     
  7. Klink Sanford
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    Klink Sanford Junior Member

    I made three test samples using different rollers to get the pattern I like, on all three I used the same unwaxed gelcoat and PVA, the texture coat last. All three hardened fine, but they are a tad sticky, I barely notice it with my fingers, but when I stand barefoot on it, it is very slightly sticky (I cleaned the PVA very carefully, so that it not it). Is that what you are talking about when you said: "while hard, it may not become fully cured". It feels like a magnet for dirt. Will that slight stickiness change with time?
     
    Last edited: Dec 11, 2021
  8. ondarvr
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    ondarvr Senior Member

    Brushing the PVA may have caused a problem, it normally gives a good surface cure when sprayed.

    Wax needs to come to the surface so it can seal the gel coat off from air so it will cure tack free. When you thicken the gel coat the wax can't migrate to the surface as easily, so it may not be as tack free.

    Gel coats are not formulated to cure tack free because 99.99999% of all gel coat is used in-mold. It just so happens that it frequently works well enough so the surface seems tack free when wax is added. Sometimes it's good enough, sometimes it's not.
     
  9. Klink Sanford
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    Klink Sanford Junior Member

    You said in another thread that the PVA has
     
  10. Klink Sanford
    Joined: Dec 2021
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    Klink Sanford Junior Member

    To recap my results, like I said, I want to roller and brush apply gelcoat ( with no sand or other non-skid additive) as non-skid over an epoxied deck that has cured for one year in a barn (out of the sun). I studied all the different advice on the internet, and concluded that it'd be a good idea to test everything on plywood so my mistakes just cost me a little gelcoat and time. As far as the pattern of the no-skid I didn't like the pattern of any NAP roller, the good news is I found that the Home Depot 9 in. x 3/8 in. Loop Texture Roller Cover, Unique Goop Loop Pattern RC-119 (430646 ?), leaves a really uniform surface. It is made of some plastic so does not absorb paint, it is made just to texture. That's the good news.

    The bad news is that the gelcoat does not harden over the epoxy, although the epoxy was applied over a year ago, and the amine had been washed off over a year ago and the surface sanded. The gelcoat just sat there for 6 days slowly hardening from a wet stage to now dry in 90% of the surface and still rubbery on the rest. I did 12 tests on Plywood, formica, and the epoxy deck. The gelcoat seems to be very sensitive to anything other than clean wood with no adhesive (plywood adhesive), shellac/varnish, and epoxy. It did not dry properly in any of those situations. Not drying is a MEKP problem, so there must be some reaction between MEKP and adhesives, shellac, epoxy etc. The temperatures were ideal around 70-83 degrees and I use 2% MEKP (.65 cc per Oz of gelcoat). I am in Central Florida.

    The PVA did work when brushed on after the gelcoat had hardened, but it remained a tad sticky, very little, but just enough that it would be a magnet for dirt. On a smooth finish that would be no big deal as all I had to do was sand and polish and the stickiness is gone, but on the non-skid, you can't sand it smooth. I also brush applied the PVA like 8 minutes after applied the gelcoat, but of course it made a mess. I switched to wax additive after test 6, I did 12 tests.

    Bottom line: I will paint the deck on this epoxy deck boat with non-skid paint of some kind.
     
  11. gonzo
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    gonzo Senior Member

    Polyester gelcoat will harden over epoxy if it is cured. Did the leftover gelcoat harden without getting sticky? I have tested gelcoat over epoxy on some repair on my own boat. I didn't want to experiment on a customer's. After 6 years it has not blistered or peeled. If you had to add PVA to cure the gelcoat, it looks like it wasn't waxed.
     
  12. Klink Sanford
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    Klink Sanford Junior Member

    The gelcoat hardened fine in all the 12 cups in the 12 tests.
     
  13. Rumars
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    Rumars Senior Member

    You can still have gelcoated nonskid, you just have to do it differently. Buy some wax sheet, imprint the pattern on it. Apply gelcoat, then one layer of thin CSM with waxed resin. Demold the result, remove wax and sand lightly, cut to desired shape and glue onto the deck with thickened epoxy.
     
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  14. rxcomposite
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    rxcomposite Senior Member

    It will. Just add some wax solution to the gel coat before applying. This will seal the surface of the gel coat and allow it to fully cure. Without wax solution, it will cure to a certain degree but remain tacky.
     

  15. rxcomposite
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    rxcomposite Senior Member

    We do it differently. We make a female mold of any texture we like from any pvc, vinyl, or rubber sheet. The mold can be reused several times. Mask to the pattern size, apply gelcoat and 2 layers of mat, release when cured. Trim to pattern size and wet mat to the deck. Use masking tape to prevent resin over run. The space and the thickness between the non skid serves as a water run off.

    When aesthetics is not of importance, we outline the waterways/run off on the deck, apply gel coat, sprinkle sifted/very fine sand on the tacky surface, apply two layers of gel coat, the last one with wax solution.
     
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