Oxalic Acid & Caustic Soda on Gel Coat

[Ribtecer]

Hi there

I bought a wonderfully preserved but very dirty and underused Westerly 33.

I have been removing the internal lacquer from the woodwork and replacing it with varnish after lots of rubbing down and with some use of Oxalic Acid.

I have read on the internet about the wonders of using Oxalic Acid on gel coat and indeed on exterior wood work. And would like to report fantastic results on the gel coat, it neutralises orrible old stains running down the hull and those orrible brownie beige scum marks just above the water line.

Now my question, I have also read about using a mix of Caustic Soda and wallpaper paste as a stripper for antifoul, anybody used this? Does it work? And if so what mix did you use and how long does it take to strip the antifoul?

Thanks for any advice in advance.

Toby

 

[Alpha22]

Oxalic on the hull is probably best left until it gets a bit warmer for best results.....

 

[pete]

I used caustic soda mixed with wallpaper paste with good results on my last boat, it got rid of 90% of the old thick antifoul and I just had to scrape the stubborn bits. But be VERY careful. I used disposable overalls, long rubber gloves and goggles and still splashed my wrists a few times. I kept a bucket of clean water handy for when this happened. If I was doing it again I would wear a full face mask instead of the goggles.
Pete

 

[John100156]

Last year, I needed to remove some staining from outlets and along the waterline to the Gelcoat on my F43, carefully added OA crystals to warm water until it was saturated, mixed in some wallpaper paste until gloopy, a squirt of fairy to give it a bit of colour - hopped into dinghy with SWMBO, we pasted it on and rinsed off after about 10 mins, quick polish with excellent results. I love the stuff....

 

[Plevier]

Caustic soda and wallpaper paste did absolutely nothing for me, complete waste of time, I think it must depend which a/f it is up against (I don't know what it was).
It works wonderfully on ordinary Dulux type paint but pete above is absolutely right about the horrors of using it, it's vicious.

 

[William_H]

Caustic soda and wallpaper paste did absolutely nothing for me, complete waste of time, I think it must depend which a/f it is up against (I don't know what it was).
It works wonderfully on ordinary Dulux type paint but pete above is absolutely right about the horrors of using it, it's vicious.

+1 I find caustic soda seems to soften the outer layers only on Jotun A/F. On the other hand drips onto my trailer imediately srip off the antirust aluminium type paint.
Do not use a normal animal hair brush as the hair just dissolves use a nylon bristle brush. Yes it burns skin like crazy. good luck olewill