Restoring Gloss to Old Gel Coat

The gel coat on my '62 Niagara had seen better days. Because it is rather thick compared to paint, I planned to aggressively buff it out right from the start. The gel coat was so badly oxidized that it had a white patina on it that would rub off on my hands every time I touched it. Polishing by hand and using a buffing wheel in a power drill did not yield satisfactory results. What really put a shine on the gel coat is the process outlined below.

1) Use the coarsest Scotch-Brite pad with Comet Cleanser (not the Soft Scrub version, the good old abrasive Comet) and really scrub the finish. Do this by wetting the surface then sprinkle the Comet on heavily. Scrub until the cleaning solution starts to turn the color of the gel coat. That is a good indication that the oxidized surface is coming off.

Take your time with this first step because if all the loose oxidized gel coat is not removed exposing a fresh hard surface, polishing will take much longer and will not result in a high gloss finish.

2) Wash the surface clean. What is left is a really dull and even finish minus all the motley white patches, discoloration and surface stains. Try rubbing the dry surface with your hand to be sure that all the oxidized finish is off.

3) Using a 7" polisher (not a drill, use a real polishing machine) with a wool bonnet set at low speed, start polishing the surface using RUBBING compound. Use a damp disposable paintbrush, 1 to 2" size, to spread the compound on the gel coat then apply the polisher. Work in small areas, and donít rush it. Let the polisher do the work, you just guide it. Things will start to look shiny rather quickly. Feel free to make multiple applications of compound in the same area and re-polish.

After 10 or 15 minutes, you get the "hang of it" and your technique will improve. It is important to read the instruction manual that comes with the polisher if you have never used on before.

4) Repeat polishing using a POLISHING compound at slightly higher speeds to bring out a deeper gloss.

5) You can stop here and wax, or go one more step of polishing using a product like Liquid Ebony before waxing. Donít be surprised if you find that you need to wax every few days for the first week or two. I think the newly exposed layer of gel coat will absorb the wax quickly and it will take a few applications of wax to seal it up.


1) I chose to use the Scotch-Brite pads over sanding because the hardness of the gel coat has been compromised by oxidation over the years. Being unsure of how the gel coat would hold up to sanding, I felt that the Scotch-Brite pad was a safer approach. Other people have wet sanded their gel coat before polishing, but that was on boats that were only 10-15 years old. Many of these MFGís are 20, 30 and 40+ years old and it is probably better to err on the safe side rather than to accidentally sand right through the gel coat.

2) It is important to use a real polishing tool and not a buffing bonnet in a power drill. I tried using the drill, but the results were so poor, I almost gave up on polishing.

I didn't own a polisher, and tried to rent one with no luck. I saw that they run $180 to $300 for big name brands, well beyond my budget. I decided to buy the cheapest one I could find on the internet. It is a Makita knock-off, made in China, and cost $28 plus $12 shipping. Name brand is American Tool Exchange. It can be seen lying on the floor of the boat in the before/after photos. It is important to get one that has the "hook and loop" fastener on the face of the disk for attaching polishing bonnets. See #6 Below.

I would have preferred to buy a heavy duty model, but decided if the cheap-o lives to finish the boat, I got my moneys worth. Good places to look for inexpensive tools are or e-bay.

3) Depending on the results you are looking for, you may want to sand out deep scratches that show up after using the rubbing compound. That is the point where scratches and cracks are easily identified. There are still some age cracks and deep scratches that I am just going to leave as is. The fact is that when you stand 4 feet away, you can't see them, and the reflection makes it look 300% better. Automotive wax is available in colors that will help hide the spider cracks that may be in the finish.

4) The job was much easier and went much quicker once I removed all the hardware from the top side, including the windshield.

5) Be aware that the polisher will throw the polishing compound all over. Be prepared to hang drop cloths over anything in the work area that you donít want covered in compound spray.

6) The best polishing bonnet I found is made by Mikita and is priced around $15.00 at the home centers. It has the hook and loop fastener system and is bowl shaped so the rounded edges get into the corner areas of the boat well. It is the bowl shape that I liked the most. The bonnets that are flat or tie on to the polisher disk tended to get the edges worn through, or let the disk come in contact with the boat making scratches or rub marks. The Makita bonnet also did not disintegrate with use like the cheaper bonnets did and was easily washed. Because it has a bowl shape it is larger than the standard 7" bonnets, having a diameter closer to 9-10". This bonnet is not in the pictures.

7) The Rubbing and Polishing compounds used are the common compounds found at the local auto parts supplier or discount department stores like Walmart. It is inexpensive and two cans of each are enough to do most boats. I used the "No. 7" brand of compounds.


The Starboard Gunnel was not scrubbed or polished in this photo. Notice the lack of reflection from my fingers in the gel coat and the white blochy coloration in the surface. The splashwell has been polished.

The Port Gunnel after scrubbing and polishing. Notice the reflection of my fingers in the gel coat.

After polishing and waxing. Although there are some scratches and spider cracks in the finish, from a few feet away, the boat looks great!

I am confident that if you follow the procedure as outlined above you will receive very satisfying results.

Mark Mullen


Copyright Mark J. Mullen 2004