Learn About Oxidation In Gel Coat

Oxidized on the left, glossy on the right.

Oxidized on the left, glossy on the right.

Here’s a quick lesson about oxidation, buffing, waxing and polishes. I promise I won’t bore you with all the technical facts about gel coat. In a non-technical nutshell, it’s porous and it soaks up stuff. Nuff said. But if you must have a slightly more technical definition of what gel coat is, it’s a polyester resin that covers fiberglass and is sprayed on in layers.

Some boat manufacturers use high quality or thicker gel coat (Tiara) and some manufacturers use thinner quality gel coat (sorry, but I have to say it… Bayliner and Tollycraft). Some manufacturers use high quality, but hard gel coat (Cobalt, Viking) where it’s thick, but requires a lot of pressure to actually cut through. Some manufacturers use medium quality gel coat that’s easy enough to work with allowing it to come back with a nice gloss (newer Sea Rays, Ocean Alexander). We’ve worked on almost every make of boat out there, so you can literally throw out a name and we could tell you all about the gel coat. (For some reason, this bores people when I’m trying to make small talk at parties.)

Here are a few common questions and quick answers:

How does oxidation occur? Anything left out in the sun will eventually oxidize, fade or disintegrate. An apple will turn brown. Metal will corrode. Wax will deteriorate allowing the gel coat to fade.

What levels of oxidation are there on gel coat? Light (the boat still has a light shine to it), medium (not much of a shine left, matte finish in most areas) and heavy (when you wipe your finger over the gel coat, it leaves a chalky residue on your finger).

What removes oxidation? Typically, a big strong man with a big strong buffer. (Or a big strong woman.) To effectively remove oxidation, you have to cut through the layer of oxidized gel coat. You are essentially removing a layer of gel coat. This is why we can’t buff out older boats that have very few layers of gel coat left. It’s too risky because it’s too easy to hit primer at this point.

How long does it take for oxidation to come back? If your boat is sitting in full sun for most of the year, the wax can start to deteriorate within just a few months of being applied leaving the gel coat no longer protected from harmful UV rays. Even if your boat lives in a somewhat cloudy climate, UV rays can still get through the clouds and if you’re not using the right wax or polish or not protecting the gel coat on a regular basis, it can start to oxidize within 4 to 6 months.

Which leads us to a discussion about compounds, waxes and polishes…

Compounds are what you use to cut through the layer of oxidation on the gel coat. They are typically made of a clay or sand-like grit that when used with a high speed buffer, allows the layer of oxidation to be literally stripped or cut away in a uniform manner leaving a fresh new layer of glossy gel coat.

Wax is not usually what gives the boat it’s glossy look. What gives it a glossy look is a fresh new layer of gel coat that has no oxidation. To summarize, the oxidation is what fades the glossy gel coat and the compound is what cuts through the layer of oxidation so you can see a new, glossy layer of gel coat again. Compound doesn’t have any wax in it, so if you compound your boat to bring back the gloss, you then need to protect that fresh new layer of gel coat from harmful UV rays.

Wax is like sunscreen for gel coat. It comes in many forms such as pure carnuba wax, pure paste or liquid wax and cleaner wax, which is a wax with compound mixed in it. Don’t get stuck romanticizing the idea of using pure carnuba wax on your boat. It may be great for some applications, but because it’s a natural product, we have found that it doesn’t last very long and can sometimes yellow the gel coat. In it’s purest form, it comes in the form of a paste wax and that is often more difficult to work with than a liquid wax you can squeeze out of a bottle directly on the boat or your buffing pad.

Traditional pure liquid waxes are just that – pure (meaning they have no compound mixed in with them) and liquid (meaning you can pour them from the bottle. They are easy to work with and offer protection for about six months depending on just how much direct sun your boat is baking in. They can add an additional amount of shine to already glossy gel coat, but if you applied pure wax over oxidized gel coat, don’t expect to get glossy results. You can’t because the oxidation is in the way. You’d basically be waxing the layer of oxidation.

Cleaner wax has compound mixed in it so that you can “clean” the gel coat as you wax. This is called a one-step process when you can clean and wax in one step. (A two-step process is when you go over the boat first with compound to remove oxidation and bring back the gloss and then you go over it again with wax to protect the gel coat.) “Cleaning” the gel coat also includes removing light to medium oxidation. That’s the job the compound is doing. It works best with a power buffer otherwise you’ll have splotchy results since it’s almost impossible to apply enough even pressure with your hand to remove oxidation without missing small areas.

Polish is somewhat of the new kid on the block, especially the more technical polymer polishes that are making their debut. We’re starting to prefer them over traditional waxes because they actually provide a shine of their own, they’re proving to last a lot longer than pure wax and they can be used on painted or gel coated surfaces.

It’s with some of these more advanced polishes that we’re using for our wax and gel coat preservation services. Once your boat is free of oxidation, we can keep it glossy and protected for years simply by applying these polishes by hand every four to eight weeks over the areas that typically fade first, allowing you to not have to have your boat buffed and waxed every single year. Your gel coat will love you for this because you won’t be stripping or cutting precious layers of it away each year and it will be protected all year long, not allowing for it to become oxidized in the first place. It’s some of the best preventative maintenance you can do!

7 comments on “Learn About Oxidation In Gel Coat”

  1. Dave Hilgendorf Reply

    You write “We’ve worked on almost every make of boat out there, so you can literally throw out a name and we could tell you all about the gel coat.” How about a 1982 Compac 23 from Hutchins?

  2. Alan Reply

    Hows’s the gel coat on a 2005 Wellcraft 330 Coastal – Fighting Lady Yellow? I’ve brought back the heavily oxidized gel by sanding and polishing. She’s looking good and will try a polymer wax to protect the gel.

    Thanks for the article.
    Alan
    Cape Cod – Massachusetts

    • Natalie Reply

      The gel coat is good on those Wellcrafts. The main thing is to keep it protected with a cleaner wax or polymer polish just like you are and your recent sanding and polishing efforts will last a long time.

  3. Jamie Reply

    This is an old thread and I hope I am able to still receive some positive and honest feedback. I recently purchased a 1996 Crownline 250CR that has shows signs of oxidation. I’ve called a few places for advice but everyone seems to give me a different answer. I tried the Mequair’s #49 Oxidation Remover on a small area, running it twice with a polisher that maxes out at 2500 rpm using a wool bonnet (changed the bonnet 3 times due to color collecting on the wool and to be sure they were continuously clean) on a small green portion of the gel coat. I still show signs of cloudiness/oxidation. I recently purchased a foam pad, as I was told to try that by a marine store. I also purchased 3M’s Auto Rubbing Compound, as this was recommended as the next step. Could you possibly give me feedback since this is a Crownline and I did my research on some of the corners they cut during that time. Your feedback would be greatly appreciated! I can send pictures, if needed since this won’t allow me to add any.

    • Natalie Reply

      Hi Jamie. Send me an email with pics to deckhanddetailing@hotmail.com. If it’s heavily oxidized and it’s a colored hull, the oxidation is in the paint now and you may be better off painting the hull. It sounds like you’ve tried all the right things – polisher, wood pad, compound, etc. Send me pics and maybe I can offer further suggestions. Thanks!

  4. Chris Reply

    Hi, I own a 1981 Post 42 that is in very nice condition. The hull was last compounded and waxed in 2014 and it looked perfect. The boat is shed kept and only sees full sun when we run it. 3 weeks ago I hired a detailer to buff (compound) and wax the hull. He said it was in good shape and used a cleaner wax instead of compounding and sealing with wax. Now the hull is all cloudy and blotchy from what he did. Later he said the hull was oxidized and that was the best he could do. I asked why he used cleaner wax instead of doing a 2 step process compound/wax if it was oxidized. He said he uses cleaner wax on 95% of the boats he does. I would just like to know if it is the process he chose to do or my gel coat?

    • Natalie Reply

      Hi Chris. Sorry it’s taken me so long to get back to you on this. It sounds like this detailer may not have known what he was doing. I’d be curious as to which cleaner wax he used. If it was Meguiars, it can leave a splotchy look if he hasn’t cut through the oxidation first. There’s always a bit of oxidation on a boat that goes out into the elements, even if it’s kept in a boat shed. If the boat really only needed a one-step, he probably should have used a different cleaner wax (maybe 3M or Flagship Premium) or he should have mixed 3M Perfect It with some wax. Do you know if he for sure used a buffer? Applying any wax or cleaner wax by hand will leave a splotchy result. How does the boat look now? Still glossy or just shiny?

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