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  1. #31
    Join Date
    May 2012
    Location
    Second Coast, Ross-shire, overlooking Gruinard Bay.
    Posts
    7,380

    Default Re: Waxing / Protecting gelcoat?

    Quote Originally Posted by Marine Reflections View Post

    Robert Wilson
    "A timely post, thank you.
    I've been wondering for a while about polishing, so ask the wise ones what I should do (and how/what with) about polishing applied* two-pack International paint?

    Any advice gratefully received."


    Robert 2 seasons is pretty quick for 2 pack International to need polishing through oxidation, are you certain it’s not water scale?

    Any pics? Close up

    Hi Tony,
    Actually it was more of a question of what if, then when and what?
    The hull still looks very good* after two seasons, but I was thinking of preventative rather than remedial treatment.


    * Infuriatingly, earlier this year a dinghy with a protruding bolt-head rubbed against the hull and "chipped" a load of small holes through into the white base-coat. Any tips on filling, colouring and fairing/polishing

    Mucho appreciado,
    Robert

    Tony
    Kay Sarah Sarah
    5751.42' N 529.44' W

  2. #32
    Join Date
    Aug 2009
    Location
    Guildford, Surrey
    Posts
    1,392

    Default Re: Waxing / Protecting gelcoat?

    Quote Originally Posted by Stemar View Post
    Given the proven (in)effectiveness of currently available antifouls, I've often wondered about the possibilities of silicone wax on the hull itself. Has anyone tried it?

    Theoretically, it should make the hull slippery enough that fouling can't get a grip and anything that manages to attach itself shouldn't be able to hang on under way, even at the low speeds of a ragtop
    You're on the right track, but I imagine in the future it will be along the lines of laser etched superhydrophobic surfaces.
    It's interesting, start a thread on the subject?

  3. #33
    Join Date
    Aug 2009
    Location
    Guildford, Surrey
    Posts
    1,392

    Default Re: Waxing / Protecting gelcoat?

    Hi Tony,
    Actually it was more of a question of what if, then when and what?
    The hull still looks very good* after two seasons, but I was thinking of preventative rather than remedial treatment.


    * Infuriatingly, earlier this year a dinghy with a protruding bolt-head rubbed against the hull and "chipped" a load of small holes through into the white base-coat. Any tips on filling, colouring and fairing/polishing

    Mucho appreciado,
    Robert



    Ah, I see, preventative rather than remedial.

    So the principles of sealing off to oxygen are the same with paint, in fact for pretty much most marine surfaces.

    Oxygen will rob a surface of its atoms (in short) so a sacrificial layer will slow down this process.
    Picture an apple with a bite taken out of it and you'll see the importance of a layer that fends off oxygen.

    For hullside protective layers you have the choice of how you want the surface to interact with water.
    Do you want the water to bead on the surface, or do you want it to sheet off collectively? Hydrophobic or Hydrophillic. This decision is made by how you are going to maintain.

    If you choose to have it beading then you'll need to ensure you are able to dry the water droplets, or you'll be left with water scale that will build giving a similar appearance to oxidation. The water droplets remain but evapourate, the particles in the water will remain.
    You could always run an in-line filter from the pontoon hose and eliminate this problem. Say 100 per year on a resin vessel and medium.

    Alternatively having hullsides that force the water to bind together and run off in a sheet helps to dry the surface, but there are pros and cons with both alternatives.

    Superhydrophobic surfaces are different, water would act like clear marbles bouncing off the surface, but we are not there yet in a cost effective application, hydrophobic yes, superhydrophobic - no.

    What:
    So a good sealer to oxygen is Gtechniq's C1, this is normally followed by their EXO for beading, but left as a base layer it will seal off to oxygen and provide a hydrophillic surface that will sheet water off. It is safe for International 2 pack and gelcoat alike.
    I'm sure by now there is an alternative hydrophillic sealer as this industry moves fast.

    Filling, colouring and fairing/polishing.
    Big questions I'm afraid Robert with big answers and variables that could fill a book.
    The technique is very similar to repairing say a stone chip on your car panels; tie, primer and colour to slightly over fill on the colour. Artists brush, Cure for an age and sand down flush, from say 1500 to finishing with very, very fine paper (6000+) so recovery in the polishing is minimal.
    This of course depends on the depth, the common mistake is to fill flush with filler, then try to add the paintwork on top, the workings need to meet the outer surface with colour.

    Best tip with paint repairs is to get someone to do it, you'll only cry once. Learning how can be fun though and very rewarding.

    Tony

  4. #34
    Join Date
    May 2012
    Location
    Second Coast, Ross-shire, overlooking Gruinard Bay.
    Posts
    7,380

    Default Re: Waxing / Protecting gelcoat?

    Thank you Tony.
    Food for thought, but as pontoons are few and far between up here I fear that it would be a once-in-a-while process, whatever that might be.
    Khamsin will be ashore again this winter so I'll have a go at the Gtechnic'sC1.
    I'll also first experiment with your recommendation on a very minor scratch well under the stern, out of sight to all but fishes and seals!
    Although Khamsin is my pride and joy, and painting her in 2016 /17 was a very expensive, hard labour of love. I'm not OTT on her looks; rather I wanted to maintain her in reasonably smart condition and not have to paint her again in my lifetime.......

    Much appreciated.

    Robert
    Kay Sarah Sarah
    5751.42' N 529.44' W

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