Most efficient fiberglass technique

Discussion in 'Boatbuilding' started by MEJETSKI2000, Jul 3, 2012.

  1. MEJETSKI2000
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    MEJETSKI2000 Junior Member

    I'm getting ready to re-laminate my cockpit after making some repairs and will be applying new matt over existing prepped roving. I'd like to minimize the amount of sanding (or eliminate) as much as as possible of the new material and have it be white in color. Should I :

    (a) use laminating resin and apply finish gel-coat over it or:
    (b) use waxed fiberglass and tint it
    (c) Use finish resin, de-wax with (what) solvent and then gel-coat ?

    If I use laminating resin how long can it stand un-coated before gel-coating ?

    Thanks in advance, Pete
     
  2. tunnels

    tunnels Previous Member

    Fibreglass is glass fibre cloth and does not come waxed !!
    Resin can be waxed yes !

    Just resin coat the glass and laminate it . !! make sure its completely wet and let go hard .
    Sand paper and and then flow coat over the top !! finished !!!:D.
     
  3. MEJETSKI2000
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    MEJETSKI2000 Junior Member

    Many thanks !! :)
     
  4. midnitmike
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    midnitmike Senior Member

    (A) would be my choice. You can do all of your laminating, sanding, and surface prep without having to deal with the wax used in finish resin...it just makes the whole job easier.

    (B) Finishing resin with tint looks horrible and I doubt there's much you can do to improve the final product...except sand it and apply gelcoat.

    (C) Despite what most hardware store sales persons might tell you this is the least attractive option. Yeah the resin kicks off tack free, but so what? Unless you're able to pull off the perfect glass job more then likely you'll need to grind the surface to clean up corners, edges, and loose bits of matte anyway. If you're going for a nice finish there's still bondo, cabosil, and primers to consider using to complete the fairing process.

    To minimize grinding on a glass job to the extent you're indicating takes practice. The area is cleaned and prepped ahead of time, inside and outside corners are filled and sanded, all of the material is precut to fit and that usually means staggered joints and torn edges to minimize any height differences. Often finish tape or Angel Hair is used to help blend in the new glass to the existing structure. Yeah it can be done...but I wouldn't put away my grinder away just yet...;)

    MM
     
  5. SamSam
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    SamSam Senior Member

    Grinding fiberglass into dust and whipping it into the air to stick all over your hot sweaty self?.....no, probably not, never and once again, no.

    Take door number A.

    Use a non waxed laminating resin so you don't have to somehow remove all the wax.

    Take care in the laminating, be neat and spiffy, to minimize what needs to be "ground" afterwards.

    Set up a fan on the other side of the work that blows the air away. The air comes past you, over the work and then blows all the nasties away.

    Level the big lumps with a hand powered, slow speed, non dust raising, dirt cheap, environmentally correct, freshly sharpened paint scraper.

    If you want to or have to use a grinder, bear down on it until its whirling 16-24 grit disc doesn't raise dust. If it's a 1500 rpm unit, show it who's the boss and make it work at 500 rpm. It's best if it's someone else's grinder you're using.

    Position a shop vac to suck up the grindings as they come off the grinder.

    If you have to, keep a water hose close by and keep misting/spraying the work so it doesn't raise dust. It will dry perfectly satisfactorily overnite.

    If someone objects to getting the work all wet, hand them the grinder and ask them to show you how it's done. Tell them they are doing a wonderful job and you are really grateful they are showing you how it's done. Keep telling them that until everything is done.
     
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  6. tunnels

    tunnels Previous Member

    Simpler still laminate properly and use peel ply ,no bumps and no lumps and a neat job when you strip it off .
    Saves all the agro of grinders and fairing . workmanship and knowing what you doing . ! put on whats needed and dont over build just for the pleasure of tuning it to dust, try hanging the grinder up and not using it at all ,look for betterways of working !
     
  7. MEJETSKI2000
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    MEJETSKI2000 Junior Member

    Guys thanks for showing me the right path ! Since the existing surfaces are roughly finished/textured I won't have to smooth the repair sections much, if any. If I use a roller to apply gel coat are there any additives I should use to make sure it cures properly ? How many coats ?
     
  8. SamSam
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    SamSam Senior Member

    There is waxed and unwaxed gelcoat. Waxed is used for the final coat so it cures hard and is not tacky. To put a second coat of gelcoat over a first coat that was waxed, you have to first remove the wax by sanding or something. If you want to use two coats, the first should be unwaxed. The second can be put right over the first without any prep, but it should have 5% wax solution added so it cures hard and not tacky.
     
  9. MEJETSKI2000
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    MEJETSKI2000 Junior Member

    Sounds great Sam Thank You !!
     
  10. midnitmike
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    midnitmike Senior Member

    If you're going to use a roller to apply your gelcoat see if you can find a lint free type suitable for polyester resins. If you don't you'll be amazed at how much of that roller remains embedded in what could have been a nice gelcoat finish.

    MM
     

  11. MEJETSKI2000
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    MEJETSKI2000 Junior Member

    Sound advice that ! Luckily I have several marine shops close by ;-)
     
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