Hull waterline stain removal

[peteK]

Oxalic acid but make sure you wax and polish the area otherwise the staining comes back within weeks.

 

[Denek]

Thanks for the Harpic recommendation, tried it today and it works really well.

 

[38mess]

I'm going to try Harpic, thanks for the tip. I used to use oxalic acid which is ok if used in warm water, then I tried 'Grunt' which is better in my opinion, just leave it do it's magic then rinse off, but expensive. Going to get some Harpic.

 

[pandos]

Any views on the best way/ratio to make it sticky? I tried wallpaper paste last year and it went lumpy straight away. Thanks!

I use a few teaspoons in warm water until no more will dissolve... Then top up with aldi washing-up liquid... Works a treat... I use peanut butter or nutella jars...

When the rust is go one I wash it all over with a bucket of water and a sponge and then hose off...

 

[Denek]

comparison photos. One side took about an hour and I did use a scotchbrite type sponge to give it a rub. Not yet polished but it’s come up really well and at £1 a bottle from B&M what’s not to like.
any recommends for polish? Can’t remember what I used last year but it was not cheap. I think because it had the word marine in the name.

 

[Poignard]

I use a few teaspoons in warm water until no more will dissolve... Then top up with aldi washing-up liquid... Works a treat... I use peanut butter or nutella jars...

When the rust is go one I wash it all over with a bucket of water and a sponge and then hose off...

I would rather have a dirty boat than eat peanut butter or Nutella ?

Seriously though, I just dissolve oxalic acid in warm water, as you do, but I had never thought about adding washing-up liquid. But I will try it next time. What difference do you think it makes?

 

[rotrax]

It allows it to 'stick' and not run off a vertical or sloping surface.

I recently mixed 50/50 oxalic acid crystals and warm water and added to the same amount of fairy liquid. It was fairly thin, but thickened up nicely after a few days.

Works great, stays put and when washed off the detergent seems to help soap it away.

Well pleased - a kilo of crystals cost half of what a tin of Y10 costs.

 

[pandos]

Children can be used for dealing with nutella... peanut butter best spread on a hot toasted bagel with coffee for breakfast...

The washing up liquid makes it thicker and suddsy and easy to see on the fiberglass....(Put on with paint brush) when washing with the sponge so it cleans stuff that the OA would not take away... Being suddsy it helps the water to hold the grime that has been lifted off....

I got this recipe from a guy based in France and have given jars to people who routinely used y10.. many comeback for the recipe...

 

[C08]

I find Starbrite Rust Stain Remover spray works better than Y10 or Oxalic Acid in any of the application modes. As previously noted you have to do the whole hull as the contrast to uncleaned areas is enormous.

 

[KINGFISHER 8]

I found this recipe on the Ribnet forum for rust stain removal

1 litre of luke warm water
200g Oxalic acid powder (ebay)
50mls car wash detergent (any mild liquid detergent)
Wallpaper paste powder (to required consistency)

Add the acid to the water. Slowly add paste powder until mix starts to gel. Go short and leave it a while - it thickens for a few minutes. Then add detergent. Brush on, leave 10-15 mins and pressure wash off. Avoid galvanised metals, chrome etc. Wear PPE. Safe on stainless steel.

But oxalic acid is not as soluble as this suggests. Some will crystallise out as it cools I am sure Therefore reduce it to between 100g and 150 g / litre

....... Or just go to the chandler and buy something made for the job! ...

 

[Poignard]

Children can be used for dealing with nutella... peanut butter best spread on a hot toasted bagel with coffee for breakfast...

The washing up liquid makes it thicker and suddsy and easy to see on the fiberglass....(Put on with paint brush) when washing with the sponge so it cleans stuff that the OA would not take away... Being suddsy it helps the water to hold the grime that has been lifted off....

I got this recipe from a guy based in France and have given jars to people who routinely used y10.. many comeback for the recipe...

Thanks I will certainly try it.

 

[TSB240]

comparison photos. One side took about an hour and I did use a scotchbrite type sponge to give it a rub. Not yet polished but it’s come up really well and at £1 a bottle from B&M what’s not to like.
any recommends for polish? Can’t remember what I used last year but it was not cheap. I think because it had the word marine in the name.

Do you have a badly oxidised surface on your GRP? A grey( fine ) scotch brite pad as used by car body shops will remove this. It is less scratchy than using fine wet or dry and requires less work with compounding and polish to give an as new gelcoat finish.

 

[peteK]

I find Starbrite Rust Stain Remover spray works better than Y10 or Oxalic Acid in any of the application modes. As previously noted you have to do the whole hull as the contrast to uncleaned areas is enormous.

It might work well but at £28 can't see many people using it.

 

[C08]

It might work well but at £28 can't see many people using it.

Wow the last I bought was £12 - back into the garage for that old tub of Oxalic Acid!