Gel coat.

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trebor
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Gel coat.

Post by trebor » Wed May 14, 2014 9:51 pm

What grade of abrasive works best on Gel coat?
40 grit wet/dry does very little.
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Graham T
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Re: Gel coat.

Post by Graham T » Thu May 15, 2014 8:22 am

Really all depends what you are trying to do. I would have thought 40 grit would be removing stuff rapidly and leaving scratches - do you mean 400 grit? If preparing for a paint job I wouldn't go that fine - possibly up to 240 grit. If fairing up a repair I would work through the grits from 120 up to 1500 making sure each grit removed the marks from the last and finish off with rubbing compound and polish. Use lots of water with a drop of washing up liquid in it to prevent clogging. Good quality paper lasts much longer - I try and find Rhyno brand at a car finishing supplier.
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Mikey
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Re: Gel coat.

Post by Mikey » Thu May 15, 2014 9:32 am

My God! 40 W or D would almost completely remove gel coat. You should start with 400 grade and progress through finer grades finishing off with a rubbing compound. Use plenty of water with perhaps a dash of washing up liquid added.

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trebor
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Re: Gel coat.

Post by trebor » Thu May 15, 2014 10:45 pm

Hi, 40 grit, using soapy water, it is just skating over gel coat.
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Nessa
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Re: Gel coat.

Post by Nessa » Fri May 16, 2014 9:52 am

I have been using ordinary 40 grit on my orbital sander to clear up the skol moth. Nothing else was working.
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Re: Gel coat.

Post by Rupert » Fri May 16, 2014 12:11 pm

Coarse wet and dry can just skate over the surface - a bit like rubbing it with wet pebbles. You can end up with deep scratches where it takes hold, and nothing elsewhere. I've used a random orbital sander with 60 grit on gelcoat when getting a surface for painting, and that works, dry. Just mask up.

You may find that a fine grit dry on a power sander works until you have got a matt surface, and then go on to the fine grit wet and dry. Not sure what the plan is for after sanding, though. If not a repaint, then you really don't want to be losing all that gelcoat thickness, as the boat will be more likely to start soaking water up.
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Nessa
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Re: Gel coat.

Post by Nessa » Fri May 16, 2014 12:26 pm

That is my plan of action, and I have mostly been removing centuries worth of old paint, not the gel itself. You have to be pretty careful though, and a mask is essential.
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trebor
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Re: Gel coat.

Post by trebor » Fri May 16, 2014 5:11 pm

The Gel coat is in first class condition, the mast has done a cookie cutter through Hull, I have plated with hardened Aluminium, glassed over and then used Gel coat filler, all these added items sanded easily, ( I have been sanding by hand ), it is the original gel coat, it is like glass, at the moment it appears to have been polished.
I intend to get hull and topsides painted metallic pearl white ( it is the minisprint ).
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Re: Gel coat.

Post by Rupert » Fri May 16, 2014 9:25 pm

You can get primers to go over gelcoat to allow other paint to stick. Years since I've used them, so can't remember anything about them.
Rupert

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