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Gel coat repair - advice please!

Mark_Schilling

Mark_Schilling

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Joined
Mar 8, 2005
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"Home by the Sea" - Nanaimo, BC
As some of you know, I'm planning on doing some gelcoat repairs to my Romany in the next little while. The boat is yellow, and has some large chips on the hull as well as the usual surface scratches on the hull and deck. I just want to 'clean it up' a bit, and buff it back to a nice shine. I also have a thin layer of 'junk epoxy' that I applied to the hull :oops: that I'll be removing by way of a sander.

I've never worked at all with any gelcoat, so I'm looking for suggestions. Andreas was saying that getting an exact colour match would be just about impossible (and the folks at Nigel Dennis Kayaks, manufacturer of the Romany, seem to agree). :? If I can't mix an acceptable colour match, would it be advisable to sand a bit more heavily, then apply a coat over the entire hull to ensure uniform colour? I don't have any major scratches on the deck, so I should be able to sand and buff that without having to apply much filler.

What's the stuff like to work with? Is it thick, or can it be painted / rolled on? I know it's stinky... what about cure times? Any other info would be helpful. Don't be shy - I want to hear it all! :wink:

Thanks!
 
Mark, I've done a little gel coat repair work, with mixed success. Several suggestions:

0. Try a repair in an out-of-the-way area, first, to get your act together.

1. Epoxy remnants, no matter how minor, will completely inhibit cure of overlying gel coat. Sanding back to immediately underlying material is usually enough, but if you get a patch that won't cure, you may have to scrape it off and sand some more.

2. I used a kit from a marine store, and it was a good investment, having all the pigments, and enough catalyst/resin, for several small jobs. The instructions were pretty good, and will get you down the road for serviceable repairs. If you have a massive job to do, you may have to get more pigment tubes.

3. The really tough part is matching the existing colour, and overpigmenting is the bugaboo. To avoid that, premix little dabs of the pigments you think you will need with a cc or so of uncatalyzed resin (in separate containers), and then use that diluted stuff, incrementally, to reach the hue you want. The only way to see if the hue is corrent is to smear a little on the hull next to where the repair is going to be. If you get close, call it good. (I never could.)

4. Most gel coat repair kits demand that the stuff be isolated from air during cure. The kits I used gave me some clear Mylar plactic to mask over the top. That worked, but is not practical for large areas. Saran or thin plastic is not good enough at excluding air. I think you may be able to get the Mylar (as drafting vellum) from a good office supply outlet, or a drafting supply store. But, it will not fit compound curved surfaces. For those, you may be successful with mold release compound, sprayed on over the freshly laid down gel coat. (Never tried that.)

5. Expect to overfill, and use a sanding block to regain a fair surface: 80 grit dry, 220 wet, 400 wet, 600 wet, 800 wet if you're anal, and then hit it with polishing compound (1200 grit??? -- they have this at the marine supply store) until it is indistinguishable from its surroundings. This may sound like a fair bit of work, but it is pretty quick, really. It really is important to sand wet in the finer grits, because polyester resin loads sandpaper really fast.

I think you'll be impressed with your handiwork.
 
welllll...... :roll:
1. working with gel coat sucks!--it stinks, is super toxic, don't do it inside!
2. gel coat needs to be put on realy thick otherwise it doesn't cure.
3. to make it cure wile exposed to the air, you have to put air dry additive in (2-3%). also known as "waxed gel coat"
4. yes you can brush it on--but it won't be smooth.... spraying is only for the pro's :wink: (you need special equipment for that)
5. the temperatur has to be (well) abough +15c and do it on a nice and dry day!
6. only work with this stuff if you have a proper organic vapor filtermask.
7. don't do the whole hull with a brush--it will look like pooooo :roll:
8. rolling it on will look like orange peel--just much worse....
9. gel coat and resin are only good for about 1/2 a year after that it's garbage (toxic waste)
10. give me call if you need help mixing that crazy stuff.
11. fill the deep scratches first with bondo--or only with bondo and put pigment in it.

good luck :lol:
 
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