regelcating a mako 23

Discussion in 'Boatbuilding' started by leinad624, Jun 26, 2011.

  1. leinad624
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    leinad624 Junior Member

    Hello,I am new to the forum so I have a question about gelcoat.I had sanded all the peeling imron complete to the original gelcoat.I had never sprayed gelcoat until yesterday.I used a g100 tyhpe gun and was told that the gelcoat would be better if it was not thinned.sprayed the first coat with just gelcoat and hardener.I had orange peel in it but was told that is normal.Sprayed second coat with the wax added in it.Question is how long until it is not tacky anymore or did I do something wrong? I tried to lightly sand one inconspicuous area after coat 1 was fairly cured probably 8 hours or longer and it seemed the first coat still has a rubbery feel because it clogged 320 grit almost immediately.Any tips help or pointers is appreciated
     
  2. gypsy28
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    gypsy28 Senior Member

    The Gelcoat should not be tacky if you added the appropriate wax.

    I dont understand part of your post. You say you sprayed the second coat with wax added but then say you tried to sand the first coat with 320 grit ?

    If you tried to sand the tacky Gelcoat (no wax) I can understand it clogging the paper but if the Gelcoat is still tacky after wax I think you made a boo boo somewhere.

    Also, I always wet sand Gelcoat (Flowcoat if wax is added) paper lasts longer and less dust.

    In Australia we can buy a product called "patch booster" for thinning Gelcoat, brilliant stuff can almost get a 2 pac finish with minimal wet rubbing, used it on my Hobie 16

    Good Luck with your project
     
  3. leinad624
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    leinad624 Junior Member

    thank you for replying.Yes I tried to sand a little area of the first coat and gummed the paper quickly.I just got nervous because of the texture present. Like I said,I never did this before and trying to learn.So in my nerveousness I sprayed the second coat with wax and after 30 hours it is hard where I can't dig my fingernail in it so I guess I did it okay but not sure. I fill the disposable cup with gelcoat and put 1 teaspoon of hardener in it and the second coat I mixed it the same with two teaspoons of wax.It just seems with the amount of texture present that I'll end up sanding a whole coat off before it gets smooth.Any help or suggestions are greatly appreciated.
     
  4. ondarvr
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    ondarvr Senior Member

    Sanding is part the price you pay when you choose gel coat, it's not too easy to eliminate that step.

    There are products you can use to help the gel coat spray and level so there is less sanding involved, but overuse of these products can cause problems with longevity of the finish.
     
  5. gypsy28
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    gypsy28 Senior Member

    That sounds ok, You will need to do a lot of sanding to get the gelcoat back to a smooth finish.
    When spraying Gelcoat with no thinner it is near impossible (for me anyway) not to get orange peel hence the sanding. Unfortunately for you I cant see a way out without lots of sanding.
    When I resprayed my Hobie 16 catamaran with gelcoat I did pretty much what you did, neat gelcoat first layer to build up thickness, second layer with thinner and wax for a smoother finish. Then LOTS of wet rubbing 400, 600, 800, 1000, 1200 grits then lots of buffing and polishing. Hard work but worth it in the long run
    Hope this helps
     
  6. leinad624
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    leinad624 Junior Member

    The info really makes me feel better about what I have so far!As long as it is going down the right path I am okay with it.I conceeded the fact that I will be doing a lot of sanding.I had some old gelcoat on the hull already but not sure how thick it was.Should I maybe stick a third coat on for assurance?
     
  7. gypsy28
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    gypsy28 Senior Member

    re thickness, it depends on how thick you sprayed the gelcoat on, when I regelcoat a mould, I find 2 coats ample (thick coats tho)

    The problem with more coats now is adhesion. Now that you have added wax to your last coat any coats you add from now wont stick very well if at all. If you wanted to spray more coats you would need to key (the dreaded sanding word) the last coat of gelcoat to ensure a good bond. I use 400 grit for this, but it will add alot of time to your project

    Hope this helps, Good luck with your project
     
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  8. ondarvr
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    ondarvr Senior Member

    For a good gel coat to gel coat bond in a situation like this 80 grit or coarser is what should be used. Gel coat will hide even heavy and deep scratches easily, so there's no need to go with fine paper.
     
  9. leinad624
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    leinad624 Junior Member

    The only reason I would maybe want to put maybe a 4th coat is because the hull is 37 years old and trying to make sure I don't underdo it.I am spraying it with a cup gun that has a tip on it that has a pretty large opening.Guessing 2 to 2.5 mm and when it shoots it puts a good bit of texture.I have the pressure cut down to 40 to 45 psi.I seem to do better when i keep my finger on the trigger without stopping because if a stop then start again it tends to throw splatters which are small but aggrivating.With a tip that big I am not sure how thick a coat I am applying.Was thinking of maybe lightly passing a da to knock down most of texture but scared to go too low on grit.Was thinking 220 at low end but not sure as I never did this before.Thanks to all replying and helping me out.
     
  10. gypsy28
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    gypsy28 Senior Member

    I use a gelcoat gun with a 2.5 tip and usually two coats is ample thickness in my case, however it is obviously hard to advise on thickness from the other side of the world ;)

    ondarvr is correct about using 80 grit just be carefull not to take it all off ! Gelcoat is pretty tough stuff tho. I use a pneumatic random orbital sander 150mm and it works really well.

    In the case of the gelcoat splattering when you release the trigger, in my experience that means your pin is not sealing against the nozzle totally, allowing gelcoat to dribble out the nozzle and when you pull the trigger again the air pressure blasts the extra gelcoat onto what your spraying hence the splatters. Usually for me it is simply a small bit of gunk in the gun.

    If I was worried about thickness I would give a light sand with 80 or 120 just to bring it back to a level surface then lay on however many more coats I thought necessary. That being said my Hobie 16 has only 2 coats (first neat gelcoat, second thinned gelcoat) and it has lasted 3 years of heavy work bumping into rock walls and running up the beach at 12 knots and it looks like it will last another 3 years with ease

    Hope this helps
     
  11. leinad624
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    leinad624 Junior Member

    That helps a lot.I started sanding the 3 coat with320 on a da and am getting the texture out of it.It is going pretty smooth except I have some small pores on bottom and some scratches on keel just after my front stand.Also I Have run into about 5 spots the size of a half dollar coin at best where it seems the gelcoat is smearing a little.It seems to me that these little areas did not get wax on them.My question is can I fair the scratches and pores with a 3m glazing compound and touch up just these areas and the second question is what to do with the 5 small areas that did not seem to cure?I would like to think I can dab a lint free cloth in some wax and wipe it on those areas but I don't know.Thanks for all your input!
     

  12. ondarvr
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    ondarvr Senior Member

    If the reason for the spots being sticky is the lack of wax, then covering them with wax now will do nothing. Wash the spots with an acetone rag, this will remove the sticky surface.

    If you are asking if you can buff out 320 grit scratches....sometimes, but typically you will need to go finer, on a DA you may get away with 600.
     
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