Polishing GRP, simple questions from a first timer

Just did it....Re: Polishing GRP, simple questions from a first timer

Hi,

I just did it.
I polished the hull of my 24years old Sadler 26.
The gelcoat was completly dull and stained. It was more like chalk than gelcoat.

I ordered the 3M polishing compounds (Imperial Compound for the worst part, Finesse II to make it even shinier and Ultra Performance Wax for the protection). from DMS.
They offer a DVD who explains the job pretty well for 5 pounds extra, which is worth buying (but don't be fooled: the job is not as easy as the man in the video tries to tell you /forums/images/graemlins/wink.gif).

I then (because their professional polishing machine was too expensive for a 'once-off' operation) orderd one of the 4 Kilograms 'cheap' polishers with 900-3000rpm.
The most important thing is that you use a good polishing mop (wool or sheep) and no foam sponge. I tried the sponge just for fun and it didn't worked!!

So far the preparation. The job itself was pretty demanding, even with the right tools.
It took me four afternoons to do the hull of the boat.
It is not like that the machine is too heavy, the polishing itself will take a while and you have to do it twice with the compound and the finesse product.

The results nevertheless are absolutely brilliant!!!
The boat looks like new... I hope it will last, but why shouldn't it? The old gelcoat lasted over 20 years...

And in my orwn view: there might be cheaper products available, but the 3M stuff works well and considered the amount of time you have to spent it is not worth saving some money just for the sake of it.
Oh yes: the whole job would be absolutely IMPOSSIBLE to do by hand! It was even hard with the machine, I tried a small areay by hand: No fun and the result was very poor.

So in my view: it is worth doing it and I am sad that I haven't done it earlier.

Regards,
jow
 
Re: Just did it....Re: Polishing GRP, simple questions from a first timer

Well Done !

Always good to see a happy camper pleased with the results of his labours!
/forums/images/graemlins/smile.gif
 
Re: Just did it....Re: Polishing GRP, simple questions from a first timer

Why didn't the sponge work with the compound?
 
Re: Just did it....Re: Polishing GRP, simple questions from a first ti

Sounds like a great result!
I'd also be very interested to know why the foam didn't work.
There's a comparison between orbital polishers and sander-polishers on our web site machine comparison page.
Also some background on polishing, waxing and glazing on the site.
 
Re: Just did it....Re: Polishing GRP, simple questions from a first ti

Hi,

I have absolutely no clue why the sponge did not work....

The instructions on the 3M compound says something like 'use very soft cloth'.

When I ordered my polisher it came with a huge kit of extra polishing heads. The manual said: the sponge is good for old paintwork on cars. So I thought it will be good for gelcoat as well. But it wasn't /forums/images/graemlins/wink.gif

Maybe the 3M compound doesn't like sponges.

The soft woolen head did the trick. The difference was huge. I simply couldn't get a shiny surface with the sponge.

jow
 
I hand wash the boat & use ajax powder ( vim is the same) to remove general marks it also tidies up the white fading on the blue gell coat stripes if done vigorously

Oven cleaner such as Aspire is pretty good & very cheap
Excellent for small stains from fenders etc as well as the exhaust stains

However, for really yellow stains then oxalic acid with wallpaper paste is the way to go. If left on too long then a wet sponge & ajax is needed to remove it so do not leave the paste to dry
 
alt said:
Why didn't the sponge work with the compound?
Click to expand...

Bearing in mind that different wool bonnets are also more/less aggrresive, I would guess no sponge is aggressive enough for gel.. better suited to car paints.
For OP, the really good news is that once you have done the full monty,the boat stays cleaner longer, and subsequent polishing will also be pretty quick. Maybe a bit of compound for damaged areas, but otherwise, just Finesse-it and wax will do.
 
BruceDanforth said:
A bit of oxalic acid in some wallpaper paste plus a bit of food colouring so you can see where you have put the stuff on. Paint it on with a brush, leave a couple of mins and hose off. It cleans grp really well. Wear gloves and goggles.
Click to expand...

I suggest a better variant to this: mix a concentrated solution of oxalic acid with Fairy Liquid (the dark green variety) 1:1. It is MUCH easier to get off than wall paper paste, it also acts as a detergent to remove oily deposits AND it contains the green dye. The viscosity of the Fairy Liquid will ensure it remains stuck on the vertical surfaces long enough for the oxalic acid to work its chemistry.

I usually use the same bottle that the FL comes in, making sure it is either fully used up or disposed of at the end: it would not be a good idea to do the washing up with it - especially if you are one those who don't rinse their dishes :-)
 
Nice to see this old thread re-emerge.

I never reported back on the results of my 2008 question...................

.......................I ended up with a variable speed silverline, which left me with aching shoulders and a good looking hull.

The oxalic acid and wallpaper paste mixture has always worked well but the washing up liquid variant sounds worth a try.

The fine little vessel that required a polish back in 2008 has recently been sold: her larger replacement will be getting a polish next spring.
 
Dougal said:
Any reason not to use a cheap variable speed cordless drill?
Click to expand...

Won't last long on the battery. We've just about finished Rampages's hull, took us about five days using polisher and polishing heads on an angle grinder at slow speed. If I'd tried to use a battery drill. I might have been able to do about ten minutes work before the battery was flat, so we'd still be at it next month.
 
There is an alternative to all that time spent polishing: Its called sailing...
A bit of oxidation of the gelcoat topsides wont actually slow you down, or endanger the safety of those on board.
I like my boat to be clean and tidy, but i wont sacrifice potential sailing time for it.
For some people all this polishing seems to become a fetish-or an excuse not to go sailing.
:friendly_wink:
 
Holy thread revival batman!

Must have missed this one first time round.

A few thoughts:

Not the best idea to hang a polisher from anything, it's an epic fail waiting to happen.

The reason why foam pads are not as effective as wool when compounding is simple, the working grit is absorbed into the surface of the foam. Imagine placing some small ball bearings on a surface then placing the foam pad on top, the ball bearings will sink into the surface of the foam.

The same thing happens with grit particles. It will work, but it isn't effective. Foam pads have their place on gelcoat, but it is the extra finer stages and not with compound.

The reason the foam didn't gain the desired result for the OP was because the grit level had been reduced considerably and wasn't able to reach the base of the lows in the surface with the pass.

No water is needed to compound or polish, it is common for some to use water when working with a foam pad and compound on gelcoat as the foam pad heats up far too quickly without it. Good luck with the mess though.

Not sure if anyone sees polishing as a fetish?? or an excuse not to go sailing??

For some life is just too short to care about what things look like and I can respect that.
 
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