wet sanding & polishing

[smitch6]

ok i'm struggling here.....
I wet sanded the paint on my boat to get rid of brush marks etc.
1 pack marine gloss paint.

i have an electric polisher/mop proper jobby thing.

now i used a sponge head and some polish to get rid of the sanding
it worked on 1 small bit great looked like glass.

I then went onto a big panel and it didn't seem to touch it.....

I was going to use MER but it hasn't been delivered yet so i just grabbed a bottle of turtle wax polish from my local shop.

( i have some good UV wax to put on afterwards to protect it properly)

as i said on the big panel it buffed it up a bit so it was smoother but didn't really put a shine on it or remove the sanding marks.

should i use a cutting compound like G3 or meguires or Tcut etc?

and should i use a sponge mop head or a wool one.

thanks

 

[Freebee]

MER in my opinion is rubbish, you need g3 cutting compound followed by a waxing

 

[Portofino]

MER in my opinion is rubbish, you need g3 cutting compound followed by a waxing

As above
I,ve been in the Med with blue boats for 13seasons .
Kinda figured out what works best .
The sponge is for a cutting compound various grades .
3M do 3 start at the the lowest and slow speed with a power polisher .Work up if nowt seems to be happening .
After "cutting " which should remove the swirl /paint marks then use the wool mop to polish .
I find the 2 pack stuff the best from Dulon .Its a phaff but like most things the more effort in the better the result .

Use proper marine stuff stay away from Halfords !

 

[Dino]

I did a big job on the gelcoat of my Broom 37 Continental in the spring. If you are going to wet sand it you should use at least 1200 grit wet & dry paper or finer. I then used Nanotech Fast Cut Compound and finished it with Nanotech Cut & Polish. Nanotech advised me to use the wool mop for the compound and the foam mop for the polish. One tip I found on YouTube was to regularly clean the wool mop with a hard bristle brush to remove the clogged compound. I was very happy with the results but I don't really have any experience with painted surfaces.

 

[roliam]

Lots of useful info/tips here-- autogeekonline.net/forum/pictures-thursday-night-detailing-classes/79542-how-wetsand-cut-buff-gel-coat-boat.html

 

[henryf]

Regardless of brand you need to understand the difference between products and what you are trying to do.

Wet sanding scrapes away the top layer of paint leaving a dull finish. It's all scratched.

Polish merely coats the surface with a bit of jizz. It will dissolve tar, help soften bird poo and stop water and some chemicals getting into your paint. But it doesn't get rid of those scratches.

Cutting compound flattens the scratches because it is an even finer sandpaper (in the form of a paste). A coarse cutting compound will make the surface shiny but you will see swirl marks in sunshine. A finer cutting compound will get rid of the swirl marks.

Polish should be seen as a sealing layer although some polishes do contain a cutting element. Consumer polishes tend to be very limited in their cutting ability to protect punters sanding away the paint on their Montego.

You also have to remember that automotive paints have changed from the colour layer being the layer you touch and polish to clear lacquer over a coloured base coat. You can no longer cut back the coloured layer to reveal fresh paint, merely tickle the outer clear lacquer.

With boat finishes you are cutting back the coloured layer, there is no clear lacquer.

I would suggest using foam pads for cutting compound rather than wool but take advice from the product manufacturer. You also need to decide between wet or dry cutting compound.

Hope that all makes sense.

Henry

 

[Chris H]

Regardless of brand you need to understand the difference between products and what you are trying to do.

Wet sanding scrapes away the top layer of paint leaving a dull finish. It's all scratched.

Polish merely coats the surface with a bit of jizz. It will dissolve tar, help soften bird poo and stop water and some chemicals getting into your paint. But it doesn't get rid of those scratches.

Cutting compound flattens the scratches because it is an even finer sandpaper (in the form of a paste). A coarse cutting compound will make the surface shiny but you will see swirl marks in sunshine. A finer cutting compound will get rid of the swirl marks.

Polish should be seen as a sealing layer although some polishes do contain a cutting element. Consumer polishes tend to be very limited in their cutting ability to protect punters sanding away the paint on their Montego.

You also have to remember that automotive paints have changed from the colour layer being the layer you touch and polish to clear lacquer over a coloured base coat. You can no longer cut back the coloured layer to reveal fresh paint, merely tickle the outer clear lacquer.

With boat finishes you are cutting back the coloured layer, there is no clear lacquer.

I would suggest using foam pads for cutting compound rather than wool but take advice from the product manufacturer. You also need to decide between wet or dry cutting compound.

Hope that all makes sense.

Henry

Please tell me this isn't porsche Henry !

 

[henryf]

What do you mean by not Porsche ?

Granted I'm somewhat flippant in my delivery but however you package the product and no matter how much you charge the basic principles are the same. With a Porsche paint correction to remove swirl marks or surface imperfections you start with a paint thickness meter and use products like a clay bar and very specific compounds, polishes and applicators but the principles are the same in terms of what you are trying to achieve. Porsche paint is clear lacquer over base coat.

I have the boat mopped every year by Platinum Marine and it is a joy to see an expert at work. We finish off with a sealant from gtechniq which is unbeatable when applied properly. You can wipe off black marks with your finger but again, the basic principles remain the same however.

Henry

 

[Chris H]

What do you mean by not Porsche ?

Granted I'm somewhat flippant in my delivery but however you package the product and no matter how much you charge the basic principles are the same. With a Porsche paint correction to remove swirl marks or surface imperfections you start with a paint thickness meter and use products like a clay bar and very specific compounds, polishes and applicators but the principles are the same in terms of what you are trying to achieve. Porsche paint is clear lacquer over base coat.

I have the boat mopped every year by Platinum Marine and it is a joy to see an expert at work. We finish off with a sealant from gtechniq which is unbeatable when applied properly. You can wipe off black marks with your finger but again, the basic principles remain the same however.

Henry

I mean you get about a bit !

 

[henryf]

Ah I see. The very same.

Henry

 

[Nick_H]

Regardless of brand you need to understand the difference between products and what you are trying to do.

Wet sanding scrapes away the top layer of paint leaving a dull finish. It's all scratched.

Polish merely coats the surface with a bit of jizz. It will dissolve tar, help soften bird poo and stop water and some chemicals getting into your paint. But it doesn't get rid of those scratches.

Cutting compound flattens the scratches because it is an even finer sandpaper (in the form of a paste). A coarse cutting compound will make the surface shiny but you will see swirl marks in sunshine. A finer cutting compound will get rid of the swirl marks.

Polish should be seen as a sealing layer although some polishes do contain a cutting element. Consumer polishes tend to be very limited in their cutting ability to protect punters sanding away the paint on their Montego.

You also have to remember that automotive paints have changed from the colour layer being the layer you touch and polish to clear lacquer over a coloured base coat. You can no longer cut back the coloured layer to reveal fresh paint, merely tickle the outer clear lacquer.

With boat finishes you are cutting back the coloured layer, there is no clear lacquer.

I would suggest using foam pads for cutting compound rather than wool but take advice from the product manufacturer. You also need to decide between wet or dry cutting compound.

Hope that all makes sense.

Henry

I agree the terms are used inconsistently, but by definition polish will have an abrasive or chemical action to make the surface smoother. A product applied after abrasion to protect the surface from the elements is a sealer, or often just called wax if it is wax based.

 

[Marine Reflections]

Oh, the joy of writing a long winded and over explanation of things that will bore the back legs off a donkey, only to accidentally hit the back button and lose it all. :disgust:

The terminology is indeed subjective. "Give that a coat of Polish", compared with "Give that a polish".
Products have developed and the meaning has changed depending on who you ask.
To my mind polish is always 'to polish' rather than to coat or to protect.
In other words poish contains an element of improvement rather than a final coat of protection. That said 'polishes' are a wide spectrum of products that are displayed on shelves by the hundreds, I don't think the sellers want clarification as confusion seems to sell again and again.

More subjectiveness ness ness...
Wet sanding will make a surface dull - true, but it can also vastly improve a factory finish into one of the highest clarity reflections. It would depend whether one is using some 1200, or 1500 from Halfords or a 5000 Trizact disc or a 10,000 sheet.
Think of a wooded bannister rail, polished through the varnish exposing the raw wood and polishing the raw wood itself to a high sheen - all with the grit of palms and lots of traffic.
With machines you can use less grit and simulate traffic or multiple passes with less rectification required as the next stage. It will always be followed up with further stages of correction, so it will always be dull by comparison of the next stage's results.

Further to this - the grit itself (if we focus on it) will be different, the grit could be made of cheese or it could be diamonds.
The surface itself could be made of cheese or diamond.

The point here is not all surfaces require a certain grit level, it is to be discovered what works best for that application, which is why a test patch should be worked on to completion, you will discover what works best for that surface before tackling the enire job.

Here's a video of me doing the polishing and protection stages of gelcoat. Warning I'm looking fat, dressed unprofessionally, there's annoying music, no commentary and its speeded up :encouragement:

 

[volvopaul]

Interested video , most of the work I see is an application of grit compound and a wax over to make it shine , does your system last any longer ? After your work what would you recommend to use when doing a wash down?

 

[henryf]

If you polished or cut through the varnish in your analogy you would have ruined the automotive paintwork and worn through the coloured gel coat for on a boat. On cars the coloured layer essentially has no shine or protection, just colour. The clear lacquer is the outer surface and must remain so (modern cars not old cellulose paint).

Boat gelcoat is more like old cellulose in that it is a relatively thick layer of colour which smooths to a shine. You are removing and smoothing the surface of that layer but not wearing through the layer.

Sorry if my post sounds pedantic and I have a lot of respect for your work.

Henry

 

[maverickofpoole]

Oh, the joy of writing a long winded and over explanation of things that will bore the back legs off a donkey, only to accidentally hit the back button and lose it all. :disgust:

The terminology is indeed subjective. "Give that a coat of Polish", compared with "Give that a polish".
Products have developed and the meaning has changed depending on who you ask.
To my mind polish is always 'to polish' rather than to coat or to protect.
In other words poish contains an element of improvement rather than a final coat of protection. That said 'polishes' are a wide spectrum of products that are displayed on shelves by the hundreds, I don't think the sellers want clarification as confusion seems to sell again and again.

More subjectiveness ness ness...
Wet sanding will make a surface dull - true, but it can also vastly improve a factory finish into one of the highest clarity reflections. It would depend whether one is using some 1200, or 1500 from Halfords or a 5000 Trizact disc or a 10,000 sheet.
Think of a wooded bannister rail, polished through the varnish exposing the raw wood and polishing the raw wood itself to a high sheen - all with the grit of palms and lots of traffic.
With machines you can use less grit and simulate traffic or multiple passes with less rectification required as the next stage. It will always be followed up with further stages of correction, so it will always be dull by comparison of the next stage's results.

Further to this - the grit itself (if we focus on it) will be different, the grit could be made of cheese or it could be diamonds.
The surface itself could be made of cheese or diamond.

The point here is not all surfaces require a certain grit level, it is to be discovered what works best for that application, which is why a test patch should be worked on to completion, you will discover what works best for that surface before tackling the enire job.

Here's a video of me doing the polishing and protection stages of gelcoat. Warning I'm looking fat, dressed unprofessionally, there's annoying music, no commentary and its speeded up :encouragement:

You missed a bit joking aside I wish I could afford to have you refinish my boat

 

[Marine Reflections]

regarding what to use after

Interested video , most of the work I see is an application of grit compound and a wax over to make it shine , does your system last any longer ? After your work what would you recommend to use when doing a wash down?

Protection products to one side, refining the surface further gives a better stand alone protection. It makes sense that the more reflective and more uniformed the surface is, then the better protected it is. Think - bouncing rays..
In reality a lot also boils down to the original gelcoat used by the manufacturer, also if it has been badly oxidised in the past and how it is maintained in the future.

Say if I'd stopped at the compound stage and gone straight in with a wax, you might not be able to see the difference so easily. But, once the wax 'filling' has melted or eroded then the true surface condition will reveal itself.
Refining further and further to try and achieve the best clarity is IMO the best protection.

After your work what would you recommend to use when doing a wash down?
Anything PH neutral, a lot to ask and would depend on where you were to be able to get away with just that, perhaps a few drops of Viakal into the mix if previously waterspotted.
The good thing about a hydrophobic coating is that it sheds most of the dirt and fallout with just water, but again this is down to how well the surface has been refined to get the most out of it.
An in-line filter on the hose such as a resin filled vessel that window cleaners use to polish the water is a cool trick. This way you won't introduce scale to the surfaces. Bit anal but hey.
The amount of time it saves by not having to dry the surface after a clean is well worth the £100 per year to top up the resin vessel.

 

[Marine Reflections]

If you polished or cut through the varnish in your analogy you would have ruined the automotive paintwork and worn through the coloured gel coat for on a boat. On cars the coloured layer essentially has no shine or protection, just colour. The clear lacquer is the outer surface and must remain so (modern cars not old cellulose paint).

Boat gelcoat is more like old cellulose in that it is a relatively thick layer of colour which smooths to a shine. You are removing and smoothing the surface of that layer but not wearing through the layer.

Sorry if my post sounds pedantic and I have a lot of respect for your work.

Henry

My example was to highlight the fact that even with the grit of the palm of your hand it's possible to cut through and refine a surface. You would rather reach the desired point of depth with fine grits than courser grits followed by recovery - for the very reasons you mention.

On gelcoat the process is much more forgiving than it is on automotive, you have much more depth to play with as you know, whereas on cars the depth is as you say - only within the clear.

Indeed you are playing with a depth of a few microns rather than 1000's of microns. The need to be able to arrive at a given depth with less recovery required is even more important.

We can arrive at the base of the defect through say 1500 but then correct the scratches, or you can arrive at the level of correction with extreemely fine grades and very little recovery will be required.

 

[Marine Reflections]

You missed a bit joking aside I wish I could afford to have you refinish my boat

When I was about 10 I had a round of car wash clients in my town - called myself Mr Bit I thought it was funny at the time.

 

[henryf]

Love it