Cleaning Oxidisation from Gel Coat

[MarkF]

Does anyone know how to clean oxidisation from gel coat?

After a few years in the sun, there's a slight white patina which I'd like to remove to restore the green colour.

Also, I've removed the name from the bow topsides, which, as expected has left an outline where the protected gel coat is visible next to the oxidised layer. See pics.

I tried starbrite hull cleaner with underwhelming results, given its high cost. It struggled even to remove mild staining from the boot top line.

Can anyone recommend a method or compound that works, to remove the oxidisation layer?

[AndyB]

Hi,
I have recently polished my B26. In the attachment you can see the difference between polished and the before. It was all like the before.

I bought a polisher I think  it was from screwfix and had a battery already. This allows about 30 minutes of polishing ( depends on the battery size). I used 3M ( from Force4) which has everything ( so one application)  - lite version as I did not want much abrasive. I did about a sq metre at a time. You have to purchase the right pad. the ones that come with it a pretty bad. I purchased Sisha-A Wool Polishing Pads, 2 Pack 7" (180mm) Buffing Pads with Hook and Loop Back for Compound, Cutting & Polishing, 100% Natural Wool, Thick and Aggressive from Amazon.

I cleaned the hull first using a power washer on a low setting and then wiped the hull dry. I made sure the weather was not too cold.

I started on a low setting and put the 3m stuff on the pad and then slowly covered the sq metre. I then polished in the normal horizontal swipe at a 1/3 full speed and then vertical at a 2/3 speed then a mixture at full speed to polish. I then did this as far as I could. At the end I sprayed on the Speed Guard. This provides a water seal and Gel Coat protection. It is expensive but you spray on then wipe in and off with a cloth.

Make sure all cloths you use a brand new. It is worth spending on a set so you don't keep re-using.

Best of luck it worked for me - my boat came up a treat,

[MarkF]

Andy,
thank you for the great advice. This sounds exactly what I need to do.  A couple of questions please:

Did you choose the 3M for any particular reason?  Starbrite and International do similar concoctions, but I don't know how well they work - I am only wondering because 3M is out of stock in most places.

How well did the polishing work over the SY decals on the stern quarters? Was there any risk of taking them off too?

Is the Speed Guard in addition to wax, which I think is part of the 3M compound? I'm not sure which works better, or if both are required.

And how did you get on polishing between the rubbing strake and the gunwales? On the BR20 they are separated by only 13cm at the stern, with the electric polisher having an 18cm disk size (commonly).  Maybe the gap is wide enough on your boat, or did you use the polisher at an angle?  If not, my options will be a small drill-mounted polishing disk or elbow grease.

[AndyB]

Why 3M?
I have used them for years, I like the all in one so just one polishing pad - OK for once/twice a year polishing. No experience of the others. Also like a light abrasive oas only a little gel coat is removed.

Decals.
The polisher I have is a not a random orbital polisher. In other words it just spins but has a variable speed. This means if I am very careful on the pressure I can angle the polisher and get into those hard to reach places or I use elbow grease. Have not had an issue with the decals yet.

Speed Guard
I use it with Wax. So for me both work the best. I wanted that protection to stop the oxidisation for as long as possible.

The gap between the strake and gunwales
I used a cloth to put the 3M on but polished off using the machine at an angle. You have to be very careful with pressure especially when you are using it at a steep angle. Otherwise it is elbow grease.

I found a battery polisher the best - it made me stop after 30-45 minutes and no cable or paying the marina for electricity - you might have the boat at home... I found the weight helped in randomly moving the polisher as I did the horizontal then vertical stripe. I did it in a circular motion along the stripe.

Hope this helps.

Andy B

[MarkF]

Andy,
Thank you very much, that all makes perfect sense. I have no excuse not to get started now. I'll find out how much elbow grease I'm prepared to use!

[MarkandMary]

Hi Mark

I have polished many boats to remove oxidation over the years - big and small.  You can get 3", 5" and 6" hook and loop polishing heads and mops at reasonable prices from several suppliers (check amazon as a starting place).  A 3" mop is ideal for dealing with the hull above the rubbing strake.  They are normally supplied with an adapter to work in an electric drill (used on a slow speed setting).  Obviously it will be quicker to do the main hull areas with the bigger mops.

I find Mirka polarshine 35 works really well on oxidation.  Obviously it won't get rid of the scratches shown on your photographs - but if you want to get it back to near original condition, very light sanding with fine sandpaper followed by 600, 800, 1000 and 1200 grit wet/dry will get it to a point where the polarshine can quickly get it back to a gleaming finish.

I don't find sealers help with oxidation very much.  I'd give the topsides a decent wax at the start of the season and perhaps once mid-season.

The frequency of using polish to remove oxidation depends a lot on the colour of your hull (dark colours are more prone) and its solar exposure.  I'd be surprised if you needed to do it more than once every three years if you are based in the UK.

. . .  and the beauty of the BR20/BRE is there really isn't that much hull area to do - less than a day's wok unless there are a lot of deep scratches to remove.

Mark

[MarkF]

Hi Mark,

Many thanks for your advice. I was looking at smaller drill pads, so it's good to hear you think them suitable. Should save me a lot of effort.

There are a few small white scratches on the gel coat, which I'd like to remove. Fortunately, the long white line is just glue from the masking tape I used when treating the wood!

I have The Fear when it comes to sanding gel coat; I've never done it before and don't want to mess things up. I assumed the white surface scratches were where the pigment had been scratched through, although they are not deep. Are you saying that this is likely not the case and I should be able to sand them to restore the colour and then polish to restore the surface finish?  If so, I'll give it a go. Any guidance gratefully received.

[MarkandMary]

Scratches tend to show up white on any gel - put some water on them and you'll see they go the same colour as the hull.

Best to practice in an area that isn't too obvious  (rather than the bow).  Fine sandpaper to start- almost zero pressure - at 90 degrees to the scratch.  I usually mask an area around 1cm or so all the way round  to avoid adding unwanted sandpaper scratches.  Once the area is uniformly dull - start working through the grades of wet and dry - again little pressure until you get to 1000 grade and above.  You should end up with a smooth dull area with no visible sanding marks.

Remove the masking tape and then onto a polarshine compound (or some equivalent) on a damp mop.  Keep the area damp and the mop speed low-to-medium to start with.  If you have done the prep well this step shouldn't take too long at all to get a good finish.   For me this is where I stop and just apply a good quality wax.  Some people will go on to use finer polishing compounds - but I'm not that much of a perfectionist.

[MarkF]

Hi Mark,
Thanks for the detailed instructions. Extremely helpful and I feel much more informed now to have a go.

Finding a discrete patch to work on won't be so simple; most of the small scratches are at the bow🙄

I'll let you know how I get on.