No announcement yet.

How much hardener to use for gelcoat repair?

  • Filter
  • Time
  • Show
Clear All
new posts

    How much hardener to use for gelcoat repair?

    Click image for larger version

Name:	Screen Shot 2018-03-08 at 9.26.24 AM copy.jpg
Views:	1
Size:	96.4 KB
ID:	416540 I have a couple of small, cosmetic defects on the gelcoat surface of my radar arch that I want to repair. One is a 1/4" chip off the gelcoat and another is a fracture around a screw hole due to a screw having been tightened too much. Should be simple. I ordered, what turned out to be a very cheap, repair kit. The kit came in as pictured above but there are no instructions of any king regarding how much hardener to mix. Can anyone make a suggestion? I tried calling the seller but no one responded. I sent email also and I am waiting, but not much hopeful

    Retired, computer expert / executive
    Bayliner 285 Cruiser / Mercruiser QSD 4.2L 320 HP Diesel
    Live in the Bay Area, CA, USA, boat in Turkey
    D-Marin @ Turgutreis in Bodrum/Turkey

    Hard to judge small quantities, it does not take much for a chip, temps are a consideration as well as sunlight
    Count it in drops. You could try a sample piece on a surface other than on the boat Keep track of the temp. and sunlight.
    1 or 2 drops may be sufficient, over fill the chip so you can sand it smooth, a wax additive on 1 coat or the top layer of 2 coats or it will not cure, it will just dry out.

    Bayliner 3870 "ALASKA33)
    Twin 350 GM power
    Located in Seward, AK
    Retired marine surveyor


      The first thing you want to do is try and get a match on the gelcoat. Use very little of the tint mix. A small dab go a long long way with that stuff. Once you think you have a good match, put a dab on an area of fiberglass to check the match. You will find you may need to adjust the tinting. Do NOT use any hardener in the mix until you have a good match. Without using the hardener you can apply it to a nice smooth area to check the match then just wipe if off with a rag. It sounds like you have a real small repair so you might just need a drop or two of hardener. I put small pieces of plastic over the new gelcoat to let it cure. This way you do not need to use any wax.
      1999 Bayliner Ciera 2655
      5.7 Bravo 3


        Thanks guys!
        Retired, computer expert / executive
        Bayliner 285 Cruiser / Mercruiser QSD 4.2L 320 HP Diesel
        Live in the Bay Area, CA, USA, boat in Turkey
        D-Marin @ Turgutreis in Bodrum/Turkey


          15-20 drops per ounce
          Edmonds, WA
          "THE FIX"
          '93 2556 5.7 Bravo II 2.0:1 18 1/4x19 P
          (.030 over-Vortec top end-part closed cooled)
          The rebuild of my 2556
          Misc. projects thread


            tint the paste BEFORE adding the hardener... then you have an unlimited amount of time to get the tint right.

            one thing to be aware of is not to add too much hardener, as this could lead to cracking or chipping later. too much hardener is partly to blame for so many older boats having severe checking/cracking in the gelcoat, where other boats of the same age have very little...

            what I found (thru experimentation) to tint white gelcoat paste to perfectly match my gray hull, is carbon black from an acetylene torch .... I collected some of the black smoke that is created when acetylene burns, and then mixed a little bit of it at a time with the white paste, and it came out perfect. then I added the catalyst and applied it to the dings and dents.

            on vertical or overhead surfaces where sagging may be a problem, a piece of stiff mylar taped over the fill will help prevent the sag and will smooth the surface that can minimize the finish work later....

            NU LIBERTE'
            Salem, OR

            1989 Bayliner 2556 Convertible
            5.7 OMC Cobra - 15.5x11 prop
            N2K equipped throughout..
            2014 Ram 3500 crew cab, 6.7 Cummins
            2007 M-3705 SLC weekend warrior, 5th wheel
            '04 Polaris Sportsman 700 -- '05 Polaris Sportsman 500 HO
            Heavy Equipment Repair and Specialty Welding