minor gelcoat repair

L

lloyds

New member
I am not a fiberglass/paint guy so I am asking for help here. I got some nicks in the gelcoat on my cabernet trimmed 16 cruiser, all from a protruding bolt on a state parks dock. So the factory sends me to the suppliers of the gel coat paste, spectrum color. Same people that supply kits for boston whalers and a myriad of others. It takes a special permit to ship the kits so the C-Dory factory stays away from it. So for $48 dollars I get a bottle of Cabernet, and a bottle of off-white, together with the hardener. Directions say to mix half a bottle of paste with 10 to 12 drops hardener. Don't need that much for small nicks so I cut it in half. I mixed it on a plastic can lid. So I use a small plastic spatula to apply it to the knicks. They fill okay, but it leaves a thin film of excess around the nicks. Do I use #200 wet paper to take it all down? I certainly don't want to scratch the good surface under or around the nicks. How hard is it to do damage removing the excess, while taking down the repaired areas?
 
I've been starting with 320-grit wet paper with a block, taking it almost down to flat. Next, I use 600-grit until the whole area of the repair and the surrounding surface are flush. Then I go over the whole area with 1200-grit until it all has a uniformly satin look to it. After sanding, I use a rubbing compound. Finally, I use a gelcoat polish, then wax.

This approach has worked pretty well for my recent repairs. Getting the color right was my main frustration. Close, but not dead on. Good enough for now though.

Tom
 
Yah, what Tom does, except I still have some Factory Issue matching gelcoat left.

Sometimes if the nick is deep you'll need a couple of coats to get it filled.

Don
 
I've made differently shaped blocks for different repairs, but mostly I use a 2x5x3/4-inch piece of poplar (any soft wood will do) and round off the edges on the business side to keep from inadvertently applying too much pressure where I don't want it or from gouging into the gelcoat in a curved area. But that's also why I start out with 320-grit; so when I get off the repair I haven't done much damage to the surrounding area. And I try to pay attention with my eyes and by feel to make sure that I don't get into areas that don't need sanding. In the few cases where I goofed anyway, it's not far from the repair and I just go over the area with the same 600, 1200, compound, polish and wax routine.
 
After going as far as the wet sandpaper would take me I rented an automotive buffer with a 10 inch wheel. Three grits of buffing compound brought the gelcoat to a deep lustre. Remember to use a fresh buffing cloth for each grit. It is interesting to watch the sanding marks and repair edge dissapear.
Mike "Levity"
 
This is good info. I have just started the rebuild of my fathers 13 boston whaler. It came with his new boat but is in bad repair. The wood seats are shot, the varnish is just flaking off where it is still attached and stained where it is not.

There is also a lot of small dings and cracks in the gel coat that I have to fix. i have never done gel coat before and was going to ask here this week but got beat to the punch.

I am also going to replace the cable steering with a no feed back single able system from tele-flex. That should clean up a lot of room in the back.
 
You guys probably already know this, but while it is OK on a tiny scratch to just roughen, clean, prime and fill the defect, the margins will show due to the sharp demarcation of old and new coloration, even if an exact match in materials.

Larger defects benefit by beveling the edges of the defects with a medium/fine grit after the intitial roughening of the defect. This gradual blend of old and new materials makes the repair less noticeable.

John
 
drjohn71a":18ionm75 said:
You guys probably already know this, but while it is OK on a tiny scratch to just roughen, clean, prime and fill the defect, the margins will show due to the sharp demarcation of old and new coloration, even if an exact match in materials.

John
Click to expand...

I have to disagree there, John. Properly done it takes a real expert to see the demarcation. At least that's true when one uses gel coat from the original batch and the defect margins are correctly prepared. It's kinda neat to watch the defect disappear completely during the sanding process. Not so neat as the sanding block takes down the bigger area surrounding it, but it all goes away during the finishing process. Those margins cannot be 90 degree before filling! The gentlest slopes result in the best repair possible.

Don
 
Those margins cannot be 90 degree before filling! The gentlest slopes result in the best repair possible. from Don

Gosh, that sounds like what I just said! gentle slope = bevel ?

Like I said, prob' gonna get clobbered. Maybe did not word it right.

In dentistry we work with esthetic composite and porcelain repair all day long and radiating bevels blend the optics for us in those endeavors. John
 
drjohn71a":2mb371j4 said:
Gosh, that sounds like what I just said! gentle slope = bevel ?
John
Click to expand...

Yup, and it didn't register in my pea brain 'till after the other message was posted. What bounced out was that the margins will always show, which is prolly correct for folks like you who get paid to make fillings disappear at a distance of 4-6 inches, but those of us who look at the repair from the next boat over, or the pier, ain't that discerning. :mrgreen:

Don
 
I see.... looking back at my original post, it does look like the introduction said the opposite of the last part.... oh well.... You know, I type most of this stuff during brief breaks in the workload, so sometimes miss the overall view going on... John
 
I agree that spectrum color is an excellent resoucre--but mighty expensive...I have used it--because I am not that good an artist at matching colors. However, gel coat does change color with time, and that makes it a bit harder to match. I purchased a 2003 18 foot Century C at the auction after Hurricane Ivan--it had fallen 25 feet and had other boats fall on it. I used Spectrum to match for the scratchs and dings--you cannot see any of the repairs from more than a foot away--but, I did buff out the entire boat with compound after the repairs were done.

My Tom cat came with a quart of forrest green gel coat and only a pint of the white--not sure what the thinking was on that! Hopefully I won't have to use much--but there were a few dings in transport and I have found a few more--not sure if I created them, or if they were present when I first got the boat!.
 
After listening in on this conversation, I am wondering whether it might not be better (and easier!)--for small nicks and scrapes--to simply use paint?
 
Hi Folks,

I have an older boat 83). All I do is use a simple tube of slightly off white off the shelf filler, fill the nick, compound and wax. Isn't perfect, but the boat isn't either.

Fred
 
Fred-

That's exactly right, scratches the off-white are pretty easy to make disappear.

It's the trim colors, particularly the middle shades of brighter colors that are hard to match, because you have to get the blend of colors right to get the right hue, and then also get the shade right, which is the color intensity vs the grey, etc.

If one could get the boat (or part of it) to a color match machine they use in paint stores, they might be able to match it pretty close.....???

Joe.
 
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