Fiberglass Gel Coat Restoration

A while back I was working on a boat in a local yard when I happened to strike up a conversation with a fellow that owned the boat next to the one that I was working on. I immediately noticed the shine on the hull (It was a sailboat, about 35 years old) and I asked if it had recently been painted. The answer was no but that he had just applied a product called Poliglow to the hull topsides. I have to admit that the hull was clean and the shine was impressive especially considering the boat’s age.


Here’s a picture of the hull I’m talking about.

Now I’ve seen this stuff on the shelves for years under various brand names Vertiglass, Poliglow, Vivilon to name a few and I have to admit that I have never paid much attention to them preferring instead to use the “sand and conpound method” in my attempts to restore aged gel coat. After checking out the finish on the aforementioned boat I decided that maybe this deserves more research. Off I went into cyberspace and a few hours later I was able to compile enough data to make me think that this may be a viable way to re-store and maintain the appearance of fiberglass gel coat. Especially interesting was a post on one of the sailing forums by a fellow who seems to have had considerable experience with this method and abviously knew what he was talking about. We’ll discuss that further in a bit. Next, let’s start with the basics and discuss the three most common methods of gel coat restoration and some of the pros and cons of each.

1- Sand, Compound and Wax

Abrade it down using whatever, compounds, sandpapers, scotch pads, necessary. It all does the same thing, and then slowly reduce the grit size to create a smooth finish and then keep it protected because if it goes bad again, you may not have any gel coat left to restore it.

Note: This removes Gel Coat

2-Wax, Wax and More Wax

Wax it and keep it from getting worse. This may or may not improve the oxidized appearance, depending on the original condition of the surface. Wax is not very viscous and may not be a great aesthetic solution, but you keep it from getting worse and you don’t reduce the gel coat.

3-The “Shine in a Bottle” Method

Disclaimer: Before we go any further I just want to point out that I have NOT done this myself but may in the very near future. The method that I’m about to describe has been compiled from various sources of information that I have uncovered in my search.

Seal it and restore the surface gloss and color using a thin sealer that is tough and durable. There are good ones and less than good ones. A couple of well-known brand names are Poliglow and Vertiglass. I suggest that some re-search is in order before you jump in the try this. The main argument against the above products is that, while they do provide a shiny surface and are a good aesthetic solution some are not very durable and vinyl fenders may abrade the surface.

A post on one of the forums indicated that “what you want is a high solids, metal interlocked, acrylic-copolymer designed for high durability with UV absorbers” commonly known as commercial grade floor wax and to look for a Product with 20% solids or higher.

A product that fits the bill is Zep High Traffic Floor Finish, available at any Home Depot store. It’s reasonably priced, has UV absorbers and can be easily removed, if desired with available products. It is also reported to be very durable.

Material List

-Zep High Traffic Floor finish (available at Home Depot)

-Bar Keeper’s Friend (powdered, available at most hardware stores)

-TSP (Trisodium Phosphate, powdered and available at hardware stores in the paint department)

-3M scrubbies (white, fine)

-Microfiber rags (white or laundered)

-Latex gloves
Surface Prep and Application

  • Clean the Hull. First use “Bar Keeper’s Friend” and a fine 3M scrubbie. Removes surface dirt and Gel Coat Chalk.
  • Wash the surface with “TSP” (trisodium phosphate). This removes any surface oil and silicone.
  • Use a garden sprayer and mist surface with water, examine for water beading to ensure that no silicone or oil is present.
  • Dry the surface prior to application.
  • Apply wax with a damp Microfiber cloth and “wipe” it on. Dries in minutes, is self-levelling and continue for 4-6 coats until desired gloss is achieved.

The first 1-2 coats will probably look somewhat blotchy but after you get 3-4 coats applied the surface should develop a good even shine.


Re-apply 1-2 coats each season.

Ok over decals and makes for easy dirt removal