Hull stains

[Bennie]

The white gelcoat on my GRP hull suffers from the kind of brown staining which ordinary cleaners (eg Jiff/Cif) will not remove. Y10, which is a jelly containing - I think - ascorbic acid works like magic; brush on, wipe off in 5 minutes and all is snowy white again.

But I have to do that at least 3 times per season and would prefer prevention to cure. I have not yet found a preventative polish that works. Any suggestions, please? And if not, can the Y10 do any harm?

 

[steve_cronin]

Y10 is phosphoric (or oxalic) acid. You can get the same stuff as "Jenolite" rust remover from car accessory shops for about a third of the price!. It only works above 60c but will not harm your gelcoat.

A good car polish will delay the return of the staining which is either caused by diesel or rust.

There are those who would sooner have their finger nails pulled out tha put silicone wax on their beloved gelcoat for fear that they might need to get it re-painted one day and that the silicone will act as a release agent and stop the paint sticking. Personally I don't go along with this for the following reasons:-

You are going to do a really good de-greasing job (or the professionals will)

How many boats, realistically do get re-painted?

The action of the weather over the average winter will remove the wax anyway.

I used to use Turtlewax Minute wax after a cleaning with T Cut (or Farelca for the stubborn bits)and have done this on several boats over thirty years. When I decided to paint a blue sheerline on one, just for a spash of colour, following proper preparation the paint stayed on - no problem. The dedicated "Boat Wax" is just a useless liquid that doesn't seem to have any action at all. A con.

Steve Cronin

 

[golf]

Re: Hull stains to Steve Cronin

Steve 60C this is an error I hope . Want to give this product a try myself . What is the correct Temp.

 

[VMALLOWS]

There was a long thread on OXALIC acid about six months ago. You can get it in boatie form as Starbright Hull Cleaner at £10 / bottle . Its in liquid form. You can (should) be able to get crystals to make up your own at a small fraction of the cost at a chemist (probably an independent one). Certainly works, even when any amount of rubbing with so called gell cleaners/JIF etc wont shift the yellow haze. Also particularly good on rust stains caused by the anchor chain/gas bttle etc.
No danger to the gelcoat.......only to your skin! (wear gloves).

Agree with Steve that none of the boat polishes last more than a month or so and will also try silicone car polish.

 

[VMALLOWS]

Further to my previous post, I searched the archives and for anyone interested OXALIC crystals are available at £5.88/ 2.5Kg from RYDENOR.CO.UK
That would make a lot of 10% solution!
They also do Acetone, polyurethane adhesive, etc.

Fascinating site ... a bit like a specialist ScrewFix aimed specifically at woodworkers.
Drawback is £5 carriage charge under £120, but you'd probably find enough you wanted to make an order worthwhile.

 

[jfkal]

Why only cure the symptom and not rectify the problem?
I sikaflexed U-shape aluminium profiles upside down on or under the toerail. Now water collected on the deck flows over the profile, cannot bridge the gap back to the hull and drips of harmelssly into the sea. No more streaks.] and stains

 

[vyv_cox]

I have strong evidence, posted further down somewhere, that it's the polish that contributes to the yellowing. Last year I only polished one side and this has yellowed consistently throughout the season. The other side has yellowed much less, maybe due to left-over polish from previous years - I don't know. However, I shall not polish this winter and we'll see what happens.

 

[steve_cronin]

Yes 60F it should have been.. apols.....nm

..

 

[Bennie]

Thanks, chaps, for your very prompt and helpful replies. When boasting in the pub last night about my first venture into this forum, another tip arose. A yottie friend had made oxalic acid from crystals but found that the resulting solution did not adhere to the hull long enough to work. It tended to run off, leaving unsightly streaks on the antifouling (might the same apply to Jenolite?). His answer was to add wallpaper paste which, after some trial and error, produced just the right stickiness. Hmm... maybe I will stay with Y 10.
However, in the interest of scientific experiment I will polish just one side of my boat with a silicone wax as suggested before launching next year, and report back.

 

[steve_cronin]

Mix it with....

Cheap hair gel. It works well and it is usually coloured so you can "see where you've been"

Steve Cronin

 

[Poignard]

I have strong evidence, posted further down somewhere, that it's the polish that contributes to the yellowing. Last year I only polished one side and this has yellowed consistently throughout the season. The other side has yellowed much less, maybe due to left-over polish from previous years - I don't know. However, I shall not polish this winter and we'll see what happens.

'

What did happen?

 

[vyv_cox]

'

What did happen?

Such a long time ago that I don't remember! I rarely polish because previous over-enthusiastic owners have removed gelcoat almost down to the layup. There seems to be a lot less yellowing in the Mediterranean so a brief exposure to an oxalic acid product is enough. The stuff I use was bought many years ago and still has plenty left.