Gel Coat

[wrp]

My kit 075, is about 8-9 years old. I have owned it 3-4 years and have had it assembled for about two years as a Roadster. Not being particularly smart I have allowed some damage in the form of scratches and chips to occur. Today I went out and decided to see what kind of shape the Gel Coat was in. I used Acetone to clean the body and then used polish to bring out the shine. Actually I think it looks pretty good. I have searched around on the forum. Anyone got any tips on how to restore and repair the scratches and chips?


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[DaveS53]

Gel coat is a polyester resin product, much like that used with fiberglass, to build the body. It's used as the finish on most boats, since it's sprayed into the mold first. The mold is what gives the gel coat it's smooth finish. Gel coat is typically much thicker than paint, at about .030 inch.

Repairing a lot of rock chips isn't real practical, but certainly not impossible. If you repair them, they will just come back. Any paint will do the same thing. It's one of the hazards of not having front fenders. If you take the rear fenders off, the chips would be gone.

A google search on gel coat repair will bring up many articles.

[Arrowhead]

Wow, number 075! Ours are from the same litter (078 here)

Actually, since it's just the fenders that are chipped up, you could just take them off and feather edge the chipped areas and smooth with some good body filler, prime and then paint the whole fender black to match the gel coat. You can apply some of that clear stone chip guard like the roadster guys do. There are sheets and spray available.

[wrp]

Thanks that is sort of where I am heading

[UnhipPopano]

Gel Coat repair is fairly easy and well documented for boats. If the gel coat is black, matching it may not be easy [Sun changes the color of all gel over time]. The trick to very small holes and scratches is not to use too much gel and cover the repair with heavy cellophane wile it is laying up. Most gel repairs are not easy to see unless you are out in the sun and are up close.

That said, is it possible to make some protective metal covers to both cover the nicked up areas and prevent further damage?

[wrp]

The damage isn't that great, it has just accumulated over time. I am pretty excited about how much I can wet sand out. The actual number of chips through the GelCoat are not the great yet.

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[AJT '33]

The damage isn't that great, it has just accumulated over time. I am pretty excited about how much I can wet sand out. The actual number of chips through the GelCoat are not the great yet.

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Hey WRP, not sure if you have already done your work or not however Gelcoat repairs are not that difficult at all, the trick is to alleviate over sanding around the repair area. If the repairs are small then treat them the same way you would a paint chip on your car, the difference is that the Gelcoat will be thicker in consistency for the most part. If the repair is larger than a 1/4" then your going to get into a little more work. Following is a few tips and tricks for repairs.
1) With a simple Dremmel CAREFULLY grind the area where the chip isolated ONLY to roughen the fiberglass below the Gelcoat to allow for the best adhesion. no necessity to grind down your only roughening the area to the edge of the Gelcoat to give a very small feather at the edge.
2) Don't use an air hose to clean the are as you can get contaminants into the prepared area, for detailed work I actually use the "air in a can" like used to blow clean a keyboard.
3) Once cleaned lay two layers of painters tape within an eight inch of the hole repair area, you can lay it over top then carefully cut away the tape with an xacto knife.
4) Mix and prep a small amount of Gelcoat (its easier to mix several batches then one big one in the case it kicks off too quickly)
5) Trowel into the damaged area the Gelcoat filling the repair, overfill a bit as well. Once filled, take your clean putty knife and with ONE pass remove the excess above the repair. DO NOT go back and try to make it perfect, you wont. The reason you do one pass and you have two layers of tape is such that when it dries, it will not shrink down further than the top of the repair hole (unless its really thick)
6) Once you have done your one pass, remove the tape before the Gelcoat sets. Once your Gelcoat sets and depending if it had an air dry added to it, take a rag with a small amount of acetone and by wiping the repair remove the top wax or the uncured layer from the repair (helps minimize the amount of sandpaper you will use). Allow to set for a little while
7) Once the Gelcoat is set you are ready to sand, be patient and use a wet sand paper starting with no less than 220, I prefer 320 and are willing to sacrifice a few sheets. Here is where your patience will come into play, sand only over the area of the repair and alleviate sanding onto the original Gelcoat, use a small block behind your sandpaper (I use a small piece of blue or pink Styrofoam SM block). The original Gelcoat is only about 0.018" thick, your wet sandpaper WILL cut through it quickly.
TIP: When I work with Gelcoat and do repairs on colors other than black, I take an HB Pencil and will mark/scribble all over the area I want to sand. As soon as I cut through that HB pencil markings, I stop and change the paper grade to a finer grade and repeat, HB pencil mark (be generous), wet sand, move up a grade to at least 1200. Remember, each time you sand away the HB pencil marks you remove about 0.01" of Gelcoat, hence why I made sure you had a little more over your repair to sand that down first so by the time you reach your original Gelcoat your into the 8000 grit level and doing more of a polish sanding than excess material removal.
8) when you get beyond 1200 use your judgement as to when you can start using compound and polishing it to blend the repair and original colors of Gelcoat.

Hope this helps and is informative to all.

[UnhipPopano]

I have one tip to add to that list. After applying gel coat, cover with cellophane, like the wrapper on a pack of cigarettes. the cellophane should help both flatten the gel and keep the air off of it to allow it to completely cure. If done right, the sanding should be minimal and then rub and polish.

[AJT '33]

I have one tip to add to that list. After applying gel coat, cover with cellophane, like the wrapper on a pack of cigarettes. the cellophane should help both flatten the gel and keep the air off of it to allow it to completely cure. If done right, the sanding should be minimal and then rub and polish.

If you are to add anything, then apply wax paper, cellophane may stick depending on the exotherm created. Yes this will aid in a full cure to the top of the repair, just be careful not to trap any air under the sheet.

[AC Bill]

I see you mentioned polishing it, hopefully it wasn't a wax polish. It will be more work, time and money, if and when, you want it painted to remove the wax.

[wrp]

Yep unfortunately, I have a shop that knows what needs to be done, they are teaching me as they go

[erlihemi]

My shop don't teach me nothing. I was talking to the walls the other day and they didn't help a bit...