gelcoat help?

Discussion in 'Materials' started by SCUBAnut, Dec 15, 2006.

  1. SCUBAnut
    Joined: Dec 2006
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    Location: Charleston, SC

    SCUBAnut Junior Member

    I have gelcoat questions, as so far, my gelcoat repairs have been limited to non-spraying applications. I've been using finish gelcoat (with surface wax) and have to remove the wax prior to sanding. This is a messy time consuming job with rags and acetone. I've been reading the previous posts, and seem to understand that I could use laminating gelcoat (non-waxed) with Duratec high gloss additive and the gelcoat will dry rock hard without the use of surface wax or PVA, am I correct? I also want to start spraying, does anyone have a recommendation on a good, reasonably priced gun. I've researched guns and it seems any HVLP with a 2.0 or above needle should be adequate, correct? It seems the biggest pitfall with normal sprayguns versus the actual gelcoat gun that uses the disposable cups is the amount of time spent in cleaning after spraying. The compressor I own is a 4HP rated at 5.1 SCFM @ 90 PSI, so I would need a gun that will work within the air limitations of the compressor. Any advice you guys can give me will be appreciated. I am trying to repair gelcoat on my power cat, that looks like the previous owner was kin to a mud wasp, not good work. I am setting up the cat for charters and would like for it to be professional looking.
    Thanks, Owen
     
  2. Martin B
    Joined: Nov 2006
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    Location: USA

    Martin B Junior Member

    HVLP will work fine and that's the only gun you can use with that small of a compressor. They aren't hard to clean at all once you get used to it. I use deVilbiss guns which are easily rebuilt. I use wax in gel and it kicks off very well. Make sure you aren't adding to much wax and also that you are using the correct amount of catalyst. I kick at 5% in the winter and 3 in the summer. I add 10% Cooks patch aid in the winter and use 5% Wax Sol in the summer. I have not worked with Duratech but I am cautious to use anything that can make the gel patches fade different from the rest of the boat, which overtime will look bad. Good luck.


    www.bowkersfiberglass.com
     
  3. ondarvr
    Joined: Dec 2005
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    Location: Monroe WA

    ondarvr Senior Member

    If you always need to clean the surface with acetone before sanding when using a waxed gel coat, then something is not being done correctly. The repaired area should be very hard, with very little, or no gumming of the sand paper. First you need to measure the gel coat and catalyst accurately for best results, the glug glug method doesn't yield consistant results. Never use less that 1.5% or more than about 2.5%, 3% is still considered OK, but I have seen problems at 3%. Over or under catalyzing will result in a poorly cured repair, this may cause a sticky surface and poorly cured gel coat that may discolor, lose it's gloss and be less water resistant. Duratech does work, but you may give up some of the water and wheather resistance, the more you add, the more problems you may encounter. The best thing to thin gel coat with is a Patchaid type product made for gel coat, you can get it at most places that sell fiberglass products. The area needs to be warm, but not hot and don't do it in direct sunlight, it may stay sticky if you do. If the wheather is cold and humid, the cure will be slow and incomplete, again leaving a sticky surface. As for the spray gun, try one of the cheap ones first, 19 to 29 bucks, make a few repairs with it, that way if you set it up you can just throw it away. If you want a better gun then you will have a little experience and hopefully not ruin a $250.00 dollar one.
     
  4. SCUBAnut
    Joined: Dec 2006
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    Location: Charleston, SC

    SCUBAnut Junior Member

    I've been using West Marine finish gelcoat. My problem must be in catalyzing. My repairs are small, so far, and I add the catalist by counting drops, which is a guess. So far I haven't had a problem with the gelcoat remaing tacky and I've stopped cleaning the gelcoat with acetone before sanding. I get a little gum in the first sandpaper but its something I can live with. I've ordered a cheap gun as you recommended so I can learn on my larger areas that really need to be sprayed. Thanks for the info.
     
  5. ted655
    Joined: May 2003
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    Location: Butte La Rose, LA.

    ted655 Senior Member

  6. ted655
    Joined: May 2003
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    Location: Butte La Rose, LA.

    ted655 Senior Member

    :?: My question is a bit different but in the same area.
    I've bought a boat (42' Gibson). 3 years ago the prev. owner sanded & recoated with gelcoat/surface wax. In March the boat will be hauled in preperation to transport it to another area. While out of the water AND because its new home will be in saltwater from time to time, I want to recoat the bottom with coal tar epoxy (better suited to the marsh waters of its new home). Since CTE sticks to damn near everything, I thought "clen, coat, cure" and done. My CTE supplier is squawking like a magpie. "surface wax, surface wax, wax, wax...." Well, truth is, I didn't do the recoat (but I'm positive it was done right) and I've never done anything like it.
    After 3 yrs sitting in the cold fresh water lake, what has happened to this "surface" wax. Will it be an issue if I power wash & wipe down with naptha?
    I COULD use Interlux No sand Primer but at $100 a gallon, WOW!
    So those that know, please sound off. After it gets down here it will sit in the water all the time. Did I mention I'm not rich> So a "better safe than sorry" answer is not good.
    Thanks,
    :confused: :confused:
     
  7. fiberglass jack
    Joined: Dec 2005
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    Location: toronto

    fiberglass jack Senior Member

    the surface wax you are talking about is to seal the air out while the gelcoat cures this wax is gone after sanding and polishing ,the only wax you will have to worry about is regular wax that may have been applied yearly, you are going to have to sand the surface before you paint the bottom this will remove the wax, also if you get some interlux wax remover cant think of the parts number, wipe it on and rub with a scotchbrite pad then wipe clean this should remove most of the wax
     

  8. Martin B
    Joined: Nov 2006
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    Location: USA

    Martin B Junior Member

    Sand the bottom thoroughly with a coarse paper, something like 180 or even 120. Clean the bottom with acetone afterwards. Paint with confidence. I have never had anything flake off that I put on the bottom of a boat.



    www.bowkersfiberglass.com
     
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