How to remove yellow stains on boat

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Adetheheat

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The yellow stains on my white beneteau antares - whats the best way to remove them?
I tried washing up liquid - it sort of improved things a bit.
I tried a steam mop cleaner thing - didn't have too much effect.
So what else might be good - what about high powered jet wash?
 
You could try oxalic acid, e.g. this. Used to be able to buy it in powder form & dilute it yourself, not sure whether you can any more...

Beaten to it...
 
Adetheheat said:
The yellow stains on my white beneteau antares - whats the best way to remove them?
I tried washing up liquid - it sort of improved things a bit.
I tried a steam mop cleaner thing - didn't have too much effect.
So what else might be good - what about high powered jet wash?
Click to expand...
You dont say where these stains are.

Y10 is the well known product for removing waterline stains. It contains oxalic acid.

A solution of oxalic acid, thickened with wallpaper paste if necessary, can be used on the decks or elsewhere.
Oxalic acid is particularly useful for removing rust stains.

Take care when using oxalic acid or products containing it.
Gloves and eye protection.
Read the safety data
.
 
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V1701 said:
You could try oxalic acid, e.g. this. Used to be able to buy it in powder form & dilute it yourself, not sure whether you can any more...

Beaten to it...
Click to expand...
Oxalic acid crystals are readily available eg from AG Woodcare or various ebay sources.

Use a near saturated solution ( 5% will not be very effective). Does not work well at low ambient temperatures though.
.
 
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It depends on what the stain is, if it is iron based then Oxalic acid will "bleach" it ( the oxalic acid reacts with the insoluble iron oxide and converts it to the soluble iron oxalate which washes out. If it is a non iron based stain from vegetation weed etc then you can try conventional bleach perhaps make a paste with wallpaper paste to get it to stay in contact with the stained area for longer. ( something worth doing with oxalic acid as well) If neither of these work then it will be buffing the stain out with a mild abrasive either by hand or machine.

In addition to VicS comments, to make a concentrated oxalic acid solution dissolve the crystals in warm water such that there are some crystals still not in solution.
As for the safety concerns, oxalic acid is poisonous, it will not burn holes in your skin but can be adsorbed through the skin or transported to the mouth if you are careless enough to get it on your hands, if you do get it on your skin simply wash it off with cold water. Gloves and safety glasses and disposable overalls are the order of the day.
 
I use “Grunt”. I know it isn’t as cost effective as buying pure oxalic acid crystals, but I find it goes further than Y10 (which is also pretty good).
 
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Stemar said:
Buy the crystals and make up a strong solution. Add a bit of wallpaper paste so it sticks and you've basically got Y10 without the marine tax.

Several year's supply for £12 at Wessex Oxalic Acid Crystals 1 Kg

Big +1 to the safety precautions mentioned above. It isn't a particularly strong acid, nor is it THAT toxic, but...
Click to expand...
Tip of the day don't eat Rhubarb leaves 😁
 
Oxalic acid is the thing, but it's a bit of a faff getting it, mixing it and storing it, where as Harpic does the same job, easily sourced, cheap, easy to store and easy to apply - neat on a cloth or sponge. It doesn't look like it has done anything but after about ten minutes the brown stain has disappeared.
Normal precautions apply, wear washing up gloves.
 
Harpic, it will send you clean round the bend 😁

It's the hypochlorite bleach in Harpic that is doing the job by probably by bleaching the stain or abrasion as Harpic is gritty. The chemistry would be interesting whether it formed ferric chlorate which if I remember is pale yellow and fairly insoluble or it may depending on pH form the soluble ferric chloride.
My first thoughts are stick to oxalic acid to begin with.
 
38mess said:
I used a product called Grunt. Less of a faff than oxalic, but pricey but one stroke takes the yellow off
Click to expand...
Grunt seems to be a concentrated oxalic acid solution and at upwards of £20 for a litre is bloody expensive for the sake of disolving some crystals in water. I suppose the chandleries need people to buy other expensive stuff other than packs of nuts and bolts though.
 
A cheap source of Oxalic is from bee keeping supplies. Used to clean the hives pre season. You’ll enjoy a visit to a bee keeper shop: smells of fresh timber and beeswax. Worth a trip for that.
 
Y10 is fine but I have found the equivalent product from Yachticon much easier to use. It is sloppier and spreads more easily, and comes in handy bottles. I’ve scarcely ever seen Yachticon products over here but they are common in the Netherlands and Germany and they appear to be easily available online, the relevant one sold as ‘Anti-Gilb’.
 
If your boat is painted as mine is with a 2 pack paint be careful with oxalic acid. I noticed staining from oxalic acid where the water runs off the topsides and down the side of the boat.
 
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