Removing yellow water staining

[ghostlymoron]

My GRP has been stained yellowish where water has been standing. What will restore it?

 

[Champagne Murphy]

Y10 is the commercial product or you can use oxalic acid which is the active ingredient. I'm a cheapskate so I got some oxalic acid salts through the pharmacist. Dissolve in warm water some day or so in advance-it takes time to dissolve- then make up some wallpaper paste and paint onto the yellowing. 10% solution is apparently correct. Leave and wash off thoroughly. Probably a good idea to use eye protection.

 

[ghostlymoron]

How do you measure the 10%?
Edit. I've just had a look at YouTube. They did 4oz in a quart of hot water so I'm going to try that with enough wallpaper paste to stop it running straight off.

 

[Champagne Murphy]

How do you measure the 10%?
Edit. I've just had a look at YouTube. They did 4oz in a quart of hot water so I'm going to try that with enough wallpaper paste to stop it running straight off.

TBH I just guessed. Thanks for the tip!

 

[ProDave]

Aldi Caravan cleaner is the product that works for me.

 

[Fantasie 19]

This stuff came top in a recent PBO test

http://www.silkymarine.co.uk/silky-marine-bright-1-litre/

 

[essexboy]

Brick cleaner from Wickes, paint on leave for 10 mins, wash off. rubber gloves good idea.

 

[chrishelen]

I tried oven cleaner, brick cleaner all sorts on my hull, but oxalic crystals in a bucket with warm water worked good, I used a hand full in a full bucket of water, the yellow just poured off with a bit of wiping. Got the oxalic off eBay.

 

[cliffdale]

I bought some chine shine and it works!

https://www.youtube.com/watch?v=1B-adZLJuyw

 

[Alpha22]

Brick cleaner for calcium/limescale based fouling.
Oxalic acid for rust/iron oxides/yellow staining.

Horses for courses...... each will not tackle the others stains...


4 table spoons of Oxalic acid in a 3/4 full bucket of warm water. Add the acid to the water gradually......

 

[Nordild]

I tried all the tricks in the book, including Oxalic acid, to no avail.
I then, in despair, tried toilet cleaner (Citrus acid thickened) and it was just the right thing.
I have included before and after pics