Tuesday 19 March 2013

Tips for Restoring Faded Gelcoat

Time takes its toll - sun, salt and sea water will oxidise gelcoat, stealing the shine and leaving a rough, dull surface. The question is, if GRP is so good, why does this happen? It's simply that Gelcoat suffers from both oxidation and UV attack. Now, oxidation and UV damage are not the same thing. They don't have the same effect on a boat's finish and it's important to know the differences between them. Oxidation, caused by exposure to oxygen, results in the chalking you see on the palm of your hand when you touch an unprotected boat. This process is slowed by good maintenance and this means regular waxing, protecting the gelcoat from the elements.
UV damage is increased if you don't maintain the shine of your gelcoat. Shiny surfaces reflect UV rays better than dull surfaces and UV rays not only cause discolourations but can mechanically degrade the Gelcoat.
While oxidation only affects the surface, UV damage penetrates the full thickness of the gelcoat and can even damage the fibreglass beneath it. So, keeping oxidation under control will also keep UV damage at bay.
However, despite your best efforts, you will, eventually, find yourself losing the shine. Surfaces may look dull and tired and also feel rough to the touch. It may be time to consider some plastic surgery.

Blue turning white. This neglected gelcoat requires more than a quick wax!

After compounding and waxing, your boat can look like an 'After' photo too!

The Art of Compounding

The first step is to ensure that everything is totally clean, so washing is essential. A good boatwash will help to remove salts and moulds as well as other dirt and grime.

Equipment needed:

Compounding is the process of removing a fine layer of gelcoat using an abrasive polish, almost like a liquid sandpaper. It's a simple job but requires care and the right tools.
Most important is the right choice of polisher. It must be a variable speed, rotary type (grinders are far too fast) so avoid the cheap car buffers which are just not good for this work. The Silverline Sander/Polisher is great value and perfect for the job.

Attach to this a foam compounding pad and have a spare handy in case you catch a sharp object and accidentally shred it.

Boat polishing this weekend? This is what you need to take with you.

Choice of Compound
There are a multitude of different manufacturers all claiming to have the best compounds and polishes and many people have their favourite. The most popular for medium to heavy oxidation is Farecla G3. This will give a great shine on its own, but to perfect that shine, follow on with Farecla G10.
If you have just light oxidation or hazing (very fine scratches), go straight to G10. But the process is the same for any manufacturer.

Be prepared! Using a rotary polisher is messy, so ensure anything in the immediate area is removed or protected or it will become covered in compound.

Attach the foam compounding mop (medium hardness foam) to your polisher and use the water spray to wet the mop. This will help reduce heating up of the gelcoat caused by all the friction you'll be creating.

Apply compound evenly to the gelcoat, over an area no bigger than 1 square metre. With the polisher switched off, spread the compound around the area you plan to work.

Set the polisher on very slow and applying a little pressure, start compounding. Holding the mop flat to the surface of the gelcoat, keep it moving and be methodical. Keep an eye out for the surface becoming dry. When it does, either apply more compound or move on. Maintain your mop by frequent water sprays. After a few passes, the compound will breakdown and go clear - this is when you stop! 

When you have a handle on how the compound is performing you can increase the speed a little but be aware of overheating the gelcoat.

Once you have completed an area, wipe it down and examine. You don't need me to tell you to repeat if it needs it, but all the oxidation layer should be gone. Seriously neglected gelcoat may need multiple passes.

The method for using G10 or other fine cut compounds is the same. Change the compounding mop for a soft foam. Here you are looking to remove fine swirls and perfect the gloss.


Proper protection of your gelcoat is key to increasing the life and finish. A gelcoat sealer such as Crystal Glo is vital to filling in micropores that will not be filled by using a wax alone. Air trapped in these micropores will start oxidation again, even beneath a wax coat. Whatever wax or polish you use to protect your gelcoat, ensure that you reapply it regularly throughout the season.

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