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Fibreglass gel coat restoration

Gel coat surface condition

Tony Carlow: Posted on Friday, December 10, 2010 5:58 PM

Surface condition

Let me explain the importance of having a perfect reflection on your surfaces.

1) It will help the durability

2) It will provide very easy maintenance

3) It will look fantastic

So, how does a correct surface profile help with durability and easy maintenance?

In order to explain this, take a look at these doodles in an attempt to show how light reflects on a surface.

Fibreglass polishing, gelcoat restoration, Thames & South Coast, Boat polishing,

Pic 1 above shows how light should be reflected off of a smooth, fine profile, the light hits the surface once! and reflects a perfect image of the surface.

Poor reflectionFibreglass polishing, gelcoat restoration, Thames & South Coast, Boat polishing,

Pic 2 above shows light reflecting on a poor finish, the light is scattered and therefore returns a poor image.

poor reflection 2Fibreglass polishing, gelcoat restoration, Thames & South Coast, Boat polishing,

A closer sketch of pic 2 shows light being trapped between the differences of surface profile.

light trapFibreglass polishing, gelcoat restoration, Thames & South Coast, Boat polishing,

An even closer sketch demonstrates just how much more surface is under attack as the light gets trapped and bounces around before being shot out at different angles.

Of course these are examples of extreme magnification and are just sketches, but they do show how light behaves on a surface, be it smooth or rough.

The pictures above are of the same sq ft of gel coat on a sports boat. The one on the left shows a good reflection but as you can see from the one on the right, when light is added the true image is revealed. By the way this boat was only 6 months old and the owner informed me he had only cleaned it once and admitted to not pre-soaking nor pressure washing off the dirt first....Not a good start!

It is very common to make this mistake and is usually the main reason behind accelerating the breakdown. Poor 'haf job' polishing techniques coming in a close second.

I once pulled into a supermarket and was nearly jumped on by a valet.."want your van washed mate"?

"errr, what are you going to remove the grit with"?

I asked as he was only holding a bucket and sponge.

He looked at me as if I had come from another planet, looked into the bucket, frowned and said "The sponge?" A tempting offer, but I politely declined.

So how does having a micro scratched surface affect the durability of the surface?

Well, a smooth highly reflective surface, allows light to hit it once! But on a rough surface it is hit many times as the light rattles in the peaks and troughs, also more of the surface is being exposed.

This action also increases those height differences, further damaging the surface.

Tiny particles also find a home in the differences and are a pain to remove without harsh cleaners.

Oxygen also plays a huge part in the breakdown process in much the same way as UV does.

On a perfect profile you can offer quality wax as a barrier to oxygen, but with a rough surface you will only be trapping oxygen within the peaks, allowing the oxidation to continue.

Thanks for reading

Tony

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How to restore the shine to fibreglass gelcoat. by Tony Carlow

Posted on Sunday, November 21, 2010 12:40 AM

The Gel coat - silky, smooth and protective

To some the gel coat is 'fibreglass' when in fact the gel coat is a layer of un-reinforced resin on top of the fibreglass.

The purpose of the gel coat is to protect the delicate structural fibres, fibreglass on its own would not be attractive and the gel coat provides manufacturers with a cost effective solution to finishing straight from the mold.

The picture to the left shows a large chip on the gel coat, exposing the fibreglass underneath.

The effects of weather

When a new hull or superstructure is popped out of a mold, the gel coat is solid, smooth, very glossy and is easily cleaned and waxed, but this finish is subject to attack from many sources, the elements, poor cleaning and poor polishing techniques. The gloss fades to dull, it becomes difficult to clean and feels rough to the touch.

The first stage in the restoration process, cleaning

This stage is by far the most important one to get right, use a cleaner that will take off all previous waxes or coatings in order to work on the gel coat surface and not 'old wax'. Be very extensive with your washing, as any grit or dirt left on the surface will cause you problems in later stages. In short clean, de-grease, rinse and dry.

Polish

Some feel that polish is a protective coating, but polish is actually a form of surface correction. Polishes contain 'microscopic particles' (some diminishing) that restore the gloss to a surface by hand or machine abrasion (or burnishing). Depending on the severity or the lack of lustre on your surface, you can use polish that has either small particles, to tackle very light oxidation and improve gloss, right up to course particle polishes (compounds) for heavier oxidation.

It should be noted that the more aggressive polishes will need to be followed up with lighter polishes in order to remove any swirl marks / ghost tails that may have been caused in the process.

You should try and go for the least aggressive first and examine the results, it may be that this is all that is needed to restore the surfaces to where you need them.

Sanding

Sanding a surface that is as thin as gel coat should be left to the professionals. Despite being ten times thicker than the paint on your car, sanding techniques requires correct equipment and training, or you could be in trouble (quickly).

Once you have the surfaces where you want them, be sure to follow up with a good protective wax and make sure you clean the surfaces with 'wax safe' cleaners.

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Gel coat surface condition

How to restore the shine to fibreglass gelcoat. by Tony Carlow