Gelcoat surface crack repair....does this prep look good?

[SeaDooGood]

as long as it is not too much the old gel should be ok once you finish sand with 1000 grit then buff and wax.

Ok...do you think 800 grit would suffice, then rubbing compound, and was? Or should I get the 1000? Also, should I be using sanding sponges or a hard rubber sanding block? I've only used the sponges so far.

 

[jammin777]

sponges are probably ok, i think other members used them. when i did my keel bottom of hull i used a rubber sanding block because it was a large area.
as for 800 grit, im not sure but may be ok. it may take a little more buffing but dosn't hurt to trail and error. 1000 grit did a good job for me. if i recall i went 280, 400,600,800 and 1000 grit. cant wait to see your results.

 

[Sportster-2001-951C-Stock]

Hmmmm...I've never had much luck with wax paper, frankly. You must create an air-tight seal for the best/proper cure...polyethylene is best. But sounds like you've already made the move, so...good luck!

Cover the area around the repair with Frog tape, that way when you start sanding you aren't immediately getting into the adjacent (non-repaired) area. You'll find that despite your best efforts, you more than likely have some voids to go back and fill as the gelcoat shrinks somewhat as it cures. Just remember to re-activate the repaired gelcoat with acetone (after lightly scuffing it for a good bond) prior to adding MORE gelcoat.

Agree gelcoat won't cure when exposed to air but these repair kits contain a wax which floats to the surface to seal from air, right?

Anyway, for the OP, 180 is WAY to course to begin with I think probably, hopefully the surface is even enough you can start with 600 and quickly move up to 1000 or 1200 ASAP?

 

[SeaDooGood]

Agree gelcoat won't cure when exposed to air but these repair kits contain a wax which floats to the surface to seal from air, right?

Anyway, for the OP, 180 is WAY to course to begin with I think probably, hopefully the surface is even enough you can start with 600 and quickly move up to 1000 or 1200 ASAP?

That was my main problem I think. What I thought was a THIN coat of gel coat that I put on was actually thicker than I thought once I started sanding. I would have been there all day with 320 grit sanding it down. It actually still needs to be sanded down some more to get it closer to flush. That's why I had to go with 180 to start and get it knocked down.

 

[bajaman123]

That's the problem I encountered when repairing my yellow GTI...the darned gelcoat is SO thin. It makes perfect blending/feathering-in a real chore if not an impossibility. As others have noted, once you start finish wet sanding the whole repair area with very high grit paper (I've had to go to 2000 grit wet-or-dry, some will go up to 6000), it'll take some or all of the scratches out, but if you've penetrated the gelcoat, literally REMOVED it from an area, then you are simply left with the substrate.

 

[SeaDooGood]

That's the problem I encountered when repairing my yellow GTI...the darned gelcoat is SO thin. It makes perfect blending/feathering-in a real chore if not an impossibility. As others have noted, once you start finish wet sanding the whole repair area with very high grit paper (I've had to go to 2000 grit wet-or-dry, some will go up to 6000), it'll take some or all of the scratches out, but if you've penetrated the gelcoat, literally REMOVED it from an area, then you are simply left with the substrate.

I'm about to just sand the whole area down real good then work my way to fine grit 1000 and then get some yellow enamel paint and paint it....will that work? My first mistake was covering the whole area instead of just the individual grooves. I think if I would have broken it up I could have sanded/blended it easier! I'm lost now as to which way I should go with this.

 

[Sportster-2001-951C-Stock]

That was my main problem I think. What I thought was a THIN coat of gel coat that I put on was actually thicker than I thought once I started sanding. I would have been there all day with 320 grit sanding it down. It actually still needs to be sanded down some more to get it closer to flush. That's why I had to go with 180 to start and get it knocked down.

Yeah that makes sense, been there done that.

 

[jammin777]

no dont paint it just yet! be patient and sand the area with like 600 grit and get the contour and work your way to 1000 grit may want to just sand by hand if there is any contour and keep sanding till it blends in with the rest of the area, once you get that done the buff with a high speed buffing wheel with heavy compound. then med cut, light cut and hand wax. if you stick with it you may be amazed.
to me sanding gel cote is a lot like bondo but tougher. gel cote is very forgiving imo. patients is of essence.

 

[racerxxx]

Not sure how far you are from Ocean Springs, but here's a free hood, with the rest of the ski attached.

http://gulfport.craigslist.org/boa/5067834957.html

 

[SeaDooGood]

no dont paint it just yet! be patient and sand the area with like 600 grit and get the contour and work your way to 1000 grit may want to just sand by hand if there is any contour and keep sanding till it blends in with the rest of the area, once you get that done the buff with a high speed buffing wheel with heavy compound. then med cut, light cut and hand wax. if you stick with it you may be amazed.
to me sanding gel cote is a lot like bondo but tougher. gel cote is very forgiving imo. patients is of essence.

I'm going to give this a try. I plan on going over a few pinpoint air pockets with some more gel coat, then just start knocking the whole area down to almost flush, then begin with the 600 wet, then 800 wet, then 1000 wet, then rubbing compound and wax. I'll see how it turns out.

 

[bajaman123]

no dont paint it just yet! be patient and sand the area with like 600 grit and get the contour and work your way to 1000 grit may want to just sand by hand if there is any contour and keep sanding till it blends in with the rest of the area, once you get that done the buff with a high speed buffing wheel with heavy compound. then med cut, light cut and hand wax. if you stick with it you may be amazed.
to me sanding gel cote is a lot like bondo but tougher. gel cote is very forgiving imo. patients is of essence.

I'd agree that white gelcoat is very forgiving, but the colors, at least the yellow I've worked with, are simply too thin on the hull to have much (if any) room for error. Maybe my '97 GTI was just super-thin on the hood area I worked on, but I swear the gelcoat there was only about .010 - .020 thick. It really surprised me how little sanding it took to completely remove the gelcoat and get into the non-colored substrate.

 

[SeaDooGood]

I'd agree that white gelcoat is very forgiving, but the colors, at least the yellow I've worked with, are simply too thin on the hull to have much (if any) room for error. Maybe my '97 GTI was just super-thin on the hood area I worked on, but I swear the gelcoat there was only about .010 - .020 thick. It really surprised me how little sanding it took to completely remove the gelcoat and get into the non-colored substrate.

Would a thin layer of gelcoat over the surrounding areas that have faded adhere properly? Or do you actually need a groove for the gelcoat to settle in to?

 

[Sportster-2001-951C-Stock]

In the original photos the gel coat didn't look particularly thin to me, so I'm still in the (hopeful) camp of careful fine wet sanding might do the trick.

 

[SeaDooGood]

In the original photos the gel coat didn't look particularly thin to me, so I'm still in the (hopeful) camp of careful fine wet sanding might do the trick.

I'll attempt again to post another current photo. It appears that there are multiple colors showing bc of having to sand so much in some areas that it took of some of the gelcoat on the good areas.

 

[bajaman123]

Yeah...if you can, post up some pics. I'll see if it looks like what mine did.

 

[Sea Dood]

OK, I have come to this thread a bit late, sorry. You are going about this all wrong, with mostly bad advice so far. That post about the Boat US article is useless advice, too. I have never seen a video on Youtube that shows the proper way to fix your type of repair.

First, a bit about gel coat. If you buy your materials from Gelcote, Intl, make sure to specify that it includes wax additive. If you buy the quarts, as I do, it comes standard with wax. The reason you use this is so you don't have to mess with PVA post application, or mess with mylar surface film to allow it to cure properly. The wax additive takes care of this for you.

Your prep is just fine, but you need to do build it up in stages. You need to buy some Cabosil, which Gelcote and other suppliers sell, which is a silicate thickener for the gel. You mix the Cabosil with the gel coat to make a paste, get it to the thickness of Bondo. You then apply the paste to the ground out cracks, making it level with the surface, and not above the surface. Once it sets, remove the wax with wax and silicone remover (buy at body shop supply house) and a red scuffy pad to promote adhesion for the next level. Mix another batch of paste, and apply it to match the contour of the base. Repeat cleaning step. Once you get it worked to the proper level and contour with paste, then you move over to the finish coat, with no Cabosil. It is best to spray the finish coat, with a bit of styrene thinner, but if you dont have the right sprayer outfit, then just hand float a layer or two of gel over the repaired spot.

If you follow this advice, you have a quick repair with very little sanding required.