Trying to bring gel coat back to life...

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Jim715

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Hi,

I have just bought an old boat and im trying to bring the white gel coat back to make it shine again.

The trouble im having is that there is a light brownish streaks through the gel coat. I have been wet sanding down to 180 grit and it still hasnt removed it. Ive tried with 180 on the DA as well but no joy. Do i need to keep going at it?

I also gave it a wash down with an oxalic acid hull cleaner prior to the above.

Any pointers will be greatly appreciated.
 
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The brown stains will come off with an oxalic acid based cleaner such as Y10, or your home-made equivalent, but you need a warm day for it to work.
 
parsifal said:
The brown stains will come off with an oxalic acid based cleaner such as Y10, or your home-made equivalent, but you need a warm day for it to work.
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Also mix in some wallpaper paste with the oxalic acid solution to make it stick to the vertical surfaces and leave it on for half to one hour. Wash off with fresh water and repeat if necessary.
 
bumperdump said:
can be purchased locally
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Spirits of salt is another name for hydrochloric acid which can also be bought as brick cleaner. Unlikely though to be any better than an oxalic acid based cleaners except it may still work in cold conditions.
 
Just last weekend we used 125gramms of oxalic acid in 1 litre of hot water on very yellow waterlines, wiped on with a sponge, back to white in 20 minutes with no effort at all.

Edit - just noted you used a cleaner, we found buying the crystals and mixing it ourselves worked better that proprietary cleaners, buy them off ebay.

For a very stained gelcoat this may need repeating 2 or 3 times, works best the warmer it is, it was 22degrees when we did it.
 
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rbmatthews said:
Also mix in some wallpaper paste with the oxalic acid solution to make it stick to the vertical surfaces and leave it on for half to one hour. Wash off with fresh water and repeat if necessary.
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it is easier to apply and wash off if you use Fairy Liquid (1:1 vol:vol) mixed with the oxalic acid solution.... plus the detergent helps clean oily residues on the side of the hull.
 
The German firm Yachticon do a version of Y10 which is gloopier and comes in a handy bottle. In German it is Anti-Gilb. I have only occasionally seen their stuff in the UK but it is easy to find in Holland.
 
Thanks for all the advice. I went at it today with the Oxalic and paste mix (3 times) but it hasn't made any difference to the brownish streaks just cleaned up the white areas a little.

I have attched a couple of photos but its quite difficult to see. Im now thinking of either keep going with the sanding being careful not to go through or to just start compunding and polishing and be done with it.

Any thoughts?

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I have similar marks on a 43 year old Rival. I think its seeing through the gel coat, and fear than any abrading will take the gel right off. Oxalic only takes off staining.
 
Jim715 said:
Hi,

I have just bought an old boat and im trying to bring the white gel coat back to make it shine again.

The trouble im having is that there is a light brownish streaks through the gel coat. I have been wet sanding down to 180 grit and it still hasnt removed it. Ive tried with 180 on the DA as well but no joy. Do i need to keep going at it?

I also gave it a wash down with an oxalic acid hull cleaner prior to the above.

Any pointers will be greatly appreciated.
Click to expand...

Going by the pictures, I don't think you are going to have any joy with stain removers or wet n dry.

The pictures look as if the pigment of the gel wasn't mixed fully and has weathered differently.
Quite common on older hand mixed gel coat.
 
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