Compounding/ polishing

[Tomsdad]

Hi everyone. I’m looking for advice on compounding and polishing. The boat is a Birchwood 25 1975 ish. Now I have detailed many cars in my time but always with a dual action (DA) polisher and foam pads. The combination of different coloured pad and different compounds gives me the control.
But now thinking of the boat it seems that a rotary polisher is needed along with wool pads.
So first off. Is the rotary polisher a must?
Second do you use only wool pads or a combination of both?
The initial work will be in localised areas doing chips and redoing poor repairs. So very small and very localised. So used in the prepping of the repair area ( getting rid of oxidation) and then after applying the gelcoat filler, wet sand then compounding and polishing to get best result possible.
But at some stage the boat will come out of the water where I will de oxidise the whole boat.

 

[lustyd]

the process and tools are the same, but make sure what you're working on is actually oxidisation rather than UV damaged wax products which looks identical. Many people polish away their gelcoat for no good reason. Step one is always wash the boat with dish soap, step two is a wipe with alcohol. If it's still looking bad then consider compound

 

[ChromeDome]

I'd use your existing experience. DA's are one of the tools, but it really depends how much you want to do to the surface.

Gel coat, the outer layer on GRP, has less lustre but is way thicker than car paint and many start by wet sanding with DA, then gradually go finer. Rubbing may be considered at some point too, And then polish to protect the wonderful result achieved.

 

[Concerto]

A 1975 hull will definitely be a brushed application of gel coat. This should be 1 to 1.5mm thick, so compounding can remove up to 0.25mm. For compounding I use a foam head and keep the hull cool and lubricated by using a plant spray with water. Keep wiping the hull off with a damp cloth to check the hull colour and the shine on using a fine compound. My local glassfibre repair expert recommend his favourite polish for my 1980 hull as it discolours with UV light -Meguiars Flagship Marine Wax. Apply a minimum of 3 cots for longterm protection.

Flagship Marine Wax 473ml - Meguiars UK

You may find my presentation of gel coat renovation to the Westerly Owners Assocation. Much of the content will still apply to your boat, the biggest difference is Westerly used a double coat of gel coat.

 

[Tomsdad]

On the subject of gelcoat thickness. I cut a section from the boat to send away for colour matching. I was staggered by the thickness of the gelcoat.

 

[lustyd]

On a 1975 boat the one thing you can be sure of is that that won't be consistent across the moulding. It's likely that it'll be thicker than recommended all over due to the relatively basic application methods used, but there's no guarantee you won't have a thin spot

 

[ChromeDome]

Did you know that the common reason for spider cracks (not stress cracks) is too thick gelcoat?

 

[Tomsdad]

Update. Help needed.
So I purchased a Silverline 1200 rotary polisher. Also some lambs wool pads. Using 3M medium cut. The machine just has a mind of its own. Like a bucking bronco. No chance to do nice slow passes. Could it be cheap wool pads. They were £15 for a pair. I was using much more compound than I thought necessary. Just seemed to dry out as soon as I started. Tried very slow speed and faster. The pads did leave considerable amounts of fluff even though I combed them first.
Just so disappointing.
What can be wrong?

 

[johnalison]

Update. Help needed.
So I purchased a Silverline 1200 rotary polisher. Also some lambs wool pads. Using 3M medium cut. The machine just has a mind of its own. Like a bucking bronco. No chance to do nice slow passes. Could it be cheap wool pads. They were £15 for a pair. I was using much more compound than I thought necessary. Just seemed to dry out as soon as I started. Tried very slow speed and faster. The pads did leave considerable amounts of fluff even though I combed them first.
Just so disappointing.
What can be wrong?

I use a household plant spray to moisten the compound before use. It works for me but my mechanical knowledge wouldn’t cover a stamp.

 

[lustyd]

Lambs wool is normally for buffing not cutting, you need foam pads and you need to wet them. Search YouTube for polishing and you should get good instructions.

 

[ChromeDome]

A dual action polisher is much easier to manage.

I got the impression that you were aware of this, given your experience.

 

[Tomsdad]

A dual action polisher is much easier to manage.

I got the impression that you were aware of this, given your experience.

But not aggressive enough . Good for clear coat on cars. But this old boat needs to be taken in hand.

 

[Concerto]

Definitely use plenty of water spray on the hull for lubrication. I use foam pads, not wool. Wool are for polish not compounding. The Silverline polisher has a speed control wheel, set this at 3 as this is fast enough and reduces any grab on starting. Also start it off the hull and than start compounding. If you find the polisher too heavy, then use some heavy duty shock cord from the lifeline to reduce the weight.

 

[bignick]

There are loads of good videos on YouTube on starting out with a rotary polisher.
E.g.

 

[trialframe]

Having used foam pads for some time, I have now changed to a wool pad with a fine 3M compound. It seems to produce a good result and importantly it doesn't sling compound over the surrounding area.

 

[Tomsdad]

There are loads of good videos on YouTube on starting out with a rotary polisher.
E.g.

Totally agree on foam pads for cars whether using DA or rotary. The only reason I am trying wool pads on rotary is that on you tube for boats about 99.9999999% use lambs wool for compounding and buffing. I am just trying what they are preaching.
I think you’re right about lubing with water. Also I think I’m using far too much product, thinking that the wool looked so dry.

 

[bignick]

When I bought my rotary polisher, after a friend returned my DA broken, I only had foam pads. I’ve used these with very good effect on badly oxidised gel coat. I’d recommend you try them as I think they are more forgiving than a lambs wool,pad. Might take a bit longer though.
I use the Lake County CCS pads.

 

[Tomsdad]

When I bought my rotary polisher, after a friend returned my DA broken, I only had foam pads. I’ve used these with very good effect on badly oxidised gel coat. I’d recommend you try them as I think they are more forgiving than a lambs wool,pad. Might take a bit longer though.
I use the Lake County CCS pads.

 

[Tomsdad]

Much better today. Used compound sparingly and sprayed a bit of water for lubricant.
Superb results.