HELP! First gel coat repair! How do I texture deck?? (pics)

Discussion in 'Fiberglass and Composite Boat Building' started by wmflyfisher, Feb 25, 2012.

  1. wmflyfisher
    Joined: Feb 2012
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    Location: Nth West, GA

    wmflyfisher New Member

    Hey guys,

    I recently removed a T-top from my Carolina Skiff and it pulled up some of the textured deck gel coat. I ordered a quart of deck gel coat from Carolina Skiff and now I am ready to repair the spots. I have a few questions.

    1) How will I match the existing texture of the deck? It's not a pattern, just rough. I read somewhere that I could use Blue tek or something called plasticine to match it?? Like modeling clay or something?

    2) What is the ratio for hardener to gel coat? What temps do I need to make the repair?

    3) Do I need to cover the gel coat once applied to dry or can I just leave it open (in a garage) and it will dry on it's own??


    ANY help would be greatly appreciated!!!
     

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  2. wmflyfisher
    Joined: Feb 2012
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    Location: Nth West, GA

    wmflyfisher New Member

    Anybody?
     
  3. corsarul
    Joined: Feb 2012
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    Location: ploiesti romania

    corsarul New Member

    Hello! Gelcoat is the anaerobic ... that is not dry in the open. Therefore the gelcoat mix at a rate of 5% styrene-paraffin and after mixing with hardener at a rate of 1.5%. As you use the talcum powder!
    Good job!
     
  4. DavidJ
    Joined: Jun 2004
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    Location: Canada

    DavidJ Senior Member

    First of all polyester resin doesn't "dry", it cures. It hardens through a chemical reaction. You will need to use a small grinder or very rough sandpaper to remove the existing gelcoat in that area and to give the new gelcoat a nice surface that it can get some bite.

    It is impossible to tell you exactly what ratio of hardener you should use without more details. You want to use enough so that it kicks off (starts to react) within a few minutes, but not so fast that it all hardens in your pot. All sorts of things can wrong wrong if you use too much or likewise too little. Air temperature plays a HUGE role in how much hardener to use. You don't even say if your product uses a benzoyl peroxide paste type hardener or a MEKP liquid. The ratio is usually around 0.5-2% or more (trust me that is a huge difference). In either case read the manufacturer instructions very very carefully. They should have mix ratio recommendations based on temperature. And of course make a small test pot and see how it cures. You could try out some tests to see if you can get the texture right at the same time.

    On a side note that picture looks to me like a manufacturing defect. Gelcoat shouldn't just pull off. When the gelcoat is originally applied in the mould the first layers of glass should be applied while it is still tacky and a proper chemical bond would be formed between the glass and it's resin and the gelcoat resin. Meaning they are interlocked at the microscopic level and cannot be separated through physical means. What it appears I am looking at is improperly bonded gelcoat. Nevertheless you need to grind that shiny stuff off before applying your new gelcoat.

    One other thing. Corsarul is recommending a mixture of styrene and paraffin. These products are absolutely necessary to a proper cure of polyester resins however in North America they are almost always put in the product by the manufacturer and are therefore in there when you purchase it. Styrene is added to lower the viscosity of the resin. ie; it makes it runny and easier to handle. It also takes part in the chemical reaction. It is the chemical that gives fibreglass resin it's characteristic smell. I have never used resin that didn't come with this already included. Read the package. Paraffin is wax. Gelcoats that are added in a mould should not have wax in them. The wax rises to the surface of the curing resin to provide an oxygen seal. (one reason you don't want your resin to cure too quickly is because you won't give the wax time to escape) When put in a mould you would create a barrier between your gelcoat and your glass resis and you would not get a proper chemical bond. Therefore all the wax would have to be ground off. Not good. However, the wax is absolutely necessary for gelcoat added on a finished part or that used on a repair, such as yours. Without the wax the gelcoat will remain tacky as the contact with the air will not allow a proper cure to take place. Again read your label carefully. Does it contain a wax or other sealing agent to allow an air cure? If not you will need to add some to your mixture. If what you purchased was intended as a deck repair gelcoat it should already have the wax in it along with the styrene.

    Hope this helps.
     
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  5. pescaloco
    Joined: Feb 2006
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    Location: so. california

    pescaloco Senior Member

    The texture appears to be silica sand with gelcoat rolled over the top.
    Remove any loose fibers or gelcoat. Sand and taper back the edges. Roll or brush as is practical a coat of gelcoat over the bare glass surface. Next sprinkle medium grit clean/dry sand into the wet gelcoat (no wax) wait 1 hour and re-coat with more gelcoat with surface agent (wax).

    You want at least 60F (better) 70F degrees and up
    Catalyze at 2% you will only need a couple ounces of gelcoat - use a small eyedropper at 20 drops per ounce will give you 2% catalyst ratio.

    You will need to mix surfacing agent at 5% this is a wax/styrene solution that will seal the gelcoat surface from air so it will cure.
    Or you can spray PVA over the repair to seal from air
     
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  6. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    Chances are good you will not get the same textured mix, what you could achieve is perhaps a feature or motive instead of an obvious repair blob.

    It looks like the T-top was bolted in place before the deck was cured properly and was sticking to the 'foot' ? that was there. It may also be that the below deck was not supported too well and flex/shocks in the deck from the t-top fatiqued the glass/resin which delaminated the deck layer. All the glass should still there by the looks, just applying some resin should bring it all together again.

    Gell coat is for inside a mold, the stuff they do pools with is called flo-coat and is designed to exotherm ? on the outside ie the wax finish is up and not down.

    If you plan to refit the t-top I would suggest looking at the flex it has when bolted and perhaps add a plate on the inside to prevent deforming the deck. Nothing is ever easy afterwards...
     
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