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Gel Coat finishing


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I've been working on getting out all of the gel coat scratches on the boat. I worked on the transom and while it looks really good, it's not pefect. I like perfect. I wet sanded with 1200 and then 1500 grit paper and then polished with 3M Perfect-It Foam Pad Glaze. If you look closely you can see that the sanded areas are not quite a clear as the unsanded areas. It is not really noticable unless you are really looking hard and know waht areas were sanded. My thought is that this may be because I didn't use a compound to remove the small scratches from the 1500 grit sandpaper. I was planning on using 3M High Gloss Gel Coat Compound, but couldn't find it anywhere.

So the question is:

What compound would be best for removing the 1500 grit scratches?

I have a 3M Perfect-It III wool Compounding Pad already and a variable speed polisher.

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obski - I've had really nice results from Top of the Line's products. I use their light cut (for 2000 grit) on the boat and my wife's dark blue BMW. The beemer looks better than new, even after a harsh MN winter. I'm sure their medium cut scratch remover will give you very nice results....and its rated at 1500 grit. All orders were delivered very quickly from their website. Their "Trade Secret" wax is also very nice!

http://www.topoftheline.com/medium-cut-scratch-remover.html

Good luck.

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3m has an entire line. I know the finest is white and is called finese. There is one that is a little grittier and is a brownish color, but I can't think of the name. Both work well, since you can start with the drittier one and then end with finese. Also don't go in circles move across the area on a diagnol and then back the opposite way so you form an x.

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As you suspect, the problem probably is the fact that you went from 1500 to the perfect it. Any brand (Ilike 3M & Meguires) of a mediumish compound after the 1500 & then the perfect it will probably cure what ails the gelcoat. It seems like what works on auto paint doesn't always work on gelcoat, & different colors of gelcoat need different techniques. It always is an experiment it seems.

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ob -> If your doing it by hand, pick up Meguiar's medium cut cleaner, then use the fine-cut cleaner and finally swirl remover. If your doing it with a machine polisher you could probably skip the medium if you don't want to buy it and just go with fine and swirl.

Personally I would do it with a machine and start with the polisher on 2-3, using a compounding pad and medium cut cleaner. Then adjust the machine speed to 3 and continue using the compounding pad with the fine-cut cleaner. Next put on a polishing pad and run the machine up to 4-5 and use the swirl remover. Follow up with your favorite glaze and your all set. I really like the Mequiar's products but the 3M stuff is good as well.

If you ever get deep scratches that you don't want to sand on, pick up some 245. I think it's a Ditzler/PPG product, but it's essentially gravel in a can. With a machine you can really clean up some gouges, but you can really make a mess of the surrounding area if your not sure what your doing.

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After the sandpaper, try using #0000 steel wool, then a rubbing compound, then 3M Finesse-It II Finishing compound, followed by your normal wax.

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I went down to Baxter's Auto Supply and picked up a quart of 3M Perfect-It II Rubbing Compound and it worked great. It took away all of the 1500 grit scratches and the polishing glaze has it shiny like new.

There were two deep scratches I got at Shasta last year and I filled those with gel coat patch from Spectrum. There was one area that I didn't fill deep enough, or maybe it shrunk some while hardening. There is a small indention that you can feel and can see if you look at it from the right angle. It is all nice and smooth. I will need to go back and patch that area some more, but it isn't a high priority right now.

All in all I'm pretty happy with how it turned out, and I feel confident to deal with these in the future.

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I went down to Baxter's Auto Supply and picked up a quart of 3M Perfect-It II Rubbing Compound and it worked great.  It took away all of the 1500 grit scratches and the polishing glaze has it shiny like new.

There were two deep scratches I got at Shasta last year and I filled those with gel coat patch from Spectrum.  There was one area that I didn't fill deep enough, or maybe it shrunk some while hardening.  There is a small indention that you can feel and can see if you look at it from the right angle.  It is all nice and smooth.  I will need to go back and patch that area some more, but it isn't a high priority right now.

All in all I'm pretty happy with how it turned out, and I feel confident to deal with these in the future.

Gel doesn't fill pin holes and scratches very easily, it's not that unusual that you don't get it right the first time.

BTW it's good to hear the rest of the sandpaper scratches came out.

Edited by whiteVLX
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  • 3 weeks later...

Okay, I'm a newbie at waxes, polishes, compounds, etc. but want to learn how to take care of this aspect of our bu. What's the safest (i.e. least likely to do damage) way to get started with clearing up existing scuffs, water marks and light scratches on our transom?

I assume I start with a good wash, followed by some vinegar/water solution for the water spots and then get started on the gelcoat. There aren't any big scratches (that I can feel). More like small scratches and scuff marks. I've attached a couple of photos to give a sense of what I'm up against.

Your advice is greatly appreciated!

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Mike,

One thing I recommend, is to start light and see what works on a few sample scratches. try a little polishing compound, if that seems too light, try some fine brass wool (with water), then polishing compound, and wax..

If that doesn't work, go for the wet/dry sand paper (wet) ... you want to end up at about 1000 grit -

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I would try some fine cut cleaner and a machine before taking sandpaper to the hull, I tend to always be too aggressive with the sand paper and make a bigger mess than I had to start with.

But like SRR said, start light and then work slowly up to the aggressive stuff.

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Which is more dangerous: by hand or by machine? Instinct says I can do a lot more damage with a machine BICBW...

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yes, go by hand. If you are just trying to fix some scratches, just focus on those, rather than messin with the entire area.

If you arm yourself with some very fine sand paper, polishing compound, and some mild cleaner wax.. you can just work in a small area and play with it. To get the shine, it is all about removing scratches.. go from big, to smaller, to smaller..etc... until they're gone

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I was (am) a newbie at this aspect of boat care as well. I had read lots of different posts on MBO before deciding what course to follow and to get up enough nerve to give it a try. It really isn't that hard and the results are really very good and satisfying. Here are the main posts I followed, first by "LottaWatta":

A reputable gel coat professional told me to get rid of minor scratches and oxidation:

1.) wet sand with 1000 then 1500 grit sand paper (maybe as low as 600grit if imperfection is deep).

2.) Buff with 3M "High Gloss Gel Coat Compound" #05933 using only good quality SBS wool pads.

3.) Polish with 3M "Perfect It foam Pad Glaze" #05937

Always remember when wet sanding to soak your sand paper overnight before using. Use a small amount of dish soap (maybe a tea spoon in a 2/3 full five gallon bucket). Rinse paper often. Use a squeege to clear often so that you can see what you are doing. Patience. Less is more.

DON'T waste your money on a cheap buffer. You need a variable speed buffer like a Makita 9227. It is the only buffer that maintains speed under load. THIS IS IMPORTANT! They are $200, but worth every penny. It is what most of the pros I know use.

I have wet sanded and buffed and waxed using many different methods and compounds and found the 3M compunds above to be the best.

Next by "rickstd"(Jimmy Buffett on the Crew) in response to the above post:

The only thing I'd add to this is that I often use 0000 steel wool and wet sand with that. It's very fine (I use it to wax antique furniture too). Use it after the sandpaper, but before you use the rubbing compound, which will smooth out any tiny scratches left by the steel wool. Then progress to the polish and then the wax. This works great for getting surface scratches out.
Edited by obski
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Just for the record, about any common ape can use a machine and fine cut cleaner and not mess it up. :)

Problems come when you use too aggressive a compound, too much speed and too much pressure.

Edited by whiteVLX
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Man, those scratches sure do look familiar. I had some almost identical on my boat. Here is a link to a thread from the MBO site that I started about this topic. My first post has a link to some before and after pics(you'll have to scroll about half-way down to get to the scratch pics).

Here ya go

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Just for the record, about any common ape can use a machine and fine cut cleaner and not mess it up. :)

Problems come when you use too aggressive a compound, too much speed and too much pressure.

What he said. If you start using the machine & a cleaner such as Finesse It, you'll get the majority of those marks out. You can then go to a fine or medium cut rubbing compound by hand on the spots that didn't clean up with the first go-around. Just in case you're not thinking about it, use some sheets or plastic to cover your interior with, that compound will fly all over the place from the machine.

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Just in case you're not thinking about it, use some sheets or plastic to cover your interior with, that compound will fly all over the place from the machine.

Very good point Tracie! I never think to mention that and it is a pain to clean up. It gets everywhere. :)

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  • 2 years later...
Man, those scratches sure do look familiar. I had some almost identical on my boat. Here is a link to a thread from the MBO site that I started about this topic. My first post has a link to some before and after pics(you'll have to scroll about half-way down to get to the scratch pics).

Here ya go

I saw the before and after...nice work!!!! What "system" did you use...any wet sanding or just buffing out the scratches???

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