Another gelcoat restoration question!

seanfoster

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I need help! (In more ways than what this question is about but that's another story!)

On with the dufour 1800 project, the boat has been stood in a garden for the past 7 or so years and the hull, although dirty is in good condition.

I have started trying to bring the grp back to it's former glory, my proceedure was to first jet wash all of the surface grime, then compound with a coarse then fine rubbing compound (aqua buff 1000 then 2000) with a rotary polisher (the angle grinder type) and then finish with a caranuba wax.

The problem I have is the gelcoat has gone off white over the years. There are areas where there used to be vinyl lettering and stripes, these areas are pure white and for some reason there is a slight lip (I'd say about 1/4 of a mm) the exposed grp is slightly proud of the previously covered areas.

I've tried oxalic acid and it hasn't done much, I thought this would be all that I'd have to do but hasn't really touched it.

I'm thinking that sanding is the obvious answer but don't want to go through the gelcoat.
Has anyone got any ideas what has happened to my gelcoat?
On close examination there are areas of microscopic pores which seem to be discoloured.
(this is well above the waterline).

Any advice would be appreciated!
 

yoda

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The raised gel under the old lettering and the tiny holes are indicative of many years of abrasion/cutting (I have the same). If the hull is a uniform yellow then cutting and polishing will make a difference but in the long term you will probably never be able to get to the modern gleaming white without applying new gelcoat. (It can be done but unkess you have done it before it's a job for a professional. To mix oxalic strong enough I find you need to make up with warm water and then add starch (wallpaper paste) to allow it to stand on the required areas for 15 minutes or so.

Yoda
 

seanfoster

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I've just mixed some up tonight to saturation and put some wall paper paste in. I'm leaving it overnight with cling film over it to see what happens. Although it is likely to get to 0 degrees tonight and I've heard oxalic acid only works in warm temperatures?
 

Seajet

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Warning

SeanFoster,

be very careful with that oxalic acid ! I've related this story before but now seems a good time...

This was years ago, maybe 1990 ? Anyway, warning labels were not so prominent as nowadays.

To try to cut a long story short, i was preparing to paint my grp boat's topsides, and used an oxalic acid cleaner to degrease.

As the instructions said 'to neutralise rinse with water' I foolishly took this to mean it was feeble stuff !

I duly rinsed off the topsides, which were high, she was on trestles to allow lowering the drop keel.

The residue ran down my bare arms, and soon began to burn - then very quickly this became 'burn like hell'.

I rushed to the club loos and rinsed my arms off under the tap, but the burning kept increasing - by now it was really seriously painful.

I got to the stage I actually wondered if it would go down to the bone; then I was saved by a member who had been a hospital matron, who knew what to do.

She filled a basin and had me keep my arms immersed for 40 minutes plus, and eventually the pain subsided.

What's really frightening is I wasn't using eye protection...

Now I'd insist on eye, face and arm protection, and take great care of any other people around and indeed neighbouring boats.
 

seanfoster

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Seajet,
Thanks for your warning, I agree with you that the containers should have warning labels, problem is most sellers just supply them in an unlabeled container!

I spilt some on my wrist this morning and it hurt like hell, but managed to rinse it under water straight away and caught it before it did any damage. I've seen your warnings before so knew to be careful, thanks!
 

rob2

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I thought you said that the lettering area was lower than its surroundings? If so, it may be that you have some form of coating over the remainder and the lettering was masked off. It could be an epoxy coating or paint, either way it will never come back to the original white exposed under the lettering. One answer is to engrave the name on a wooden board which is then attached over the tell-tale area!

Rob.
 
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