restoring faded/mottled gelcoat

[pcatterall]

The light blue deck/superstructure on my old Neptunian was very badly faded with patches of white discolouration all over.
I thought that I would have to live with it or paint it.
Inspired by recent information on the forum ( or was it PBO) I decided to have a go at restoring a trial area.
I had to use 400 wet and dry to make any real impression then finer grades and Tcut.
On the small sections I did the results were amazing and I intend to do the lot.
I thought that I would report this in case anyone else was in 'the same boat'.

I was going to ask about the best hand tools to help with this task but will return to my previous thread about the hull discolouration on my Leisure 20 where there was some good advice which is probably applicable to this job.

It may be worth some before and after photos!!

Cheers.

 

[Delivery Skipper]

Amazing results

Oxalic Acid




www.keenmarine.co.uk

 

[ProDave]

See my other thread.

I tried some Aldi "caravan cleaner" £2.99 for 1 litre.

It gets rid of all the yellow staining above the waterline with just a gentle rub with a soft cloth.

 

[pcatterall]

This is deep discolouration of the gell coat, I cant see any 'cleaner' touching it. Only removal of the 'damaged' gell coat will do. Fortunatly the gell coat seems quite generous and I cant see any places where I have 'gone through'.

 

[Marine Reflections]

Yes, quite right it would be like mowing the lawn with a duvet!

400 is a bit harsh to start with though, are you using it wet (under a flow of water) and have tried say 800?
Of course twice as slow but twice as safe

 

[pcatterall]

Tried using 8oo and it took about 10 mins work on a 6" trial area with little effect,
tried 600 for same time with better result but still some way to go. Another trial area about 12"x6" took 10 mins with 400 then about 2 mins each with 600 and then 800.
I used wet paper and a sponge to keep area running plus 'washing' paper every minute.
I presume that this hasn't been done in the last 35 years and it was interesting to see the original ( pale blue ) colour coming back.
next step is to consider how best to 'mechanise' the process or calculate hand method....square foot = 30 mins ..... 150square feet say 75 hours then polish and wax..... another 15 hours ....!! very rough but I think an investment in 'machinery is required!!


Thanks all for the kind advice.

 

[Stu Jackson]

http://forums.catalina.sailboatowners.com/showthread.php?t=117266

 

[pcatterall]

Stu,
Many thanks for the link, it is actually the one I refered to; very comprehensive and now saved to my favourites!!
I note, however, that the author recommends doing the wet and dry by hand as there is less risk of damaging the gell coat. Perhaps when I build up some muscles I will be a bit quicker, possibly use both hands at the same time or bribe the 'crew' ?
Thanks again

 

[Marine Reflections]

Without a doubt, that is the best postings on the subject I have ever read!

Yes it will take longer with a finer start, but it is safer and easier to bring back to full clarity as the correction would have been more uniform.

I don't think that 400 - 600 are good grades to start with for the DIY.

I couldn't use that to speed the job up as I wouldn't be 100% of the history of the boat and you would be removing a fair amount of gel there, if it's yours then perhaps you may be more bold, but I still think returning from 600 is a big ask, it may look as if they are gone as a polished surface would hide them but not remove them under close inspection.


For machine profiling I prefer the electric Mirca DA

 

[pcatterall]

Thanks Marine Reflections for the tips.
The test areas I did ( ending up with the 400 grit ) looked ok but I guess that you are saying that there would probably be deep scratches not visable to the naked eye.
I will try again with the 600 to start ( 800 would have taken about 30mins for a 6" square) Perhaps if I get 75% of the way there with 600 ( 10mins) then the next 25% with 800 ( 10mins again) then the 800 will have removed the scratches from the 600.
My original thoughts had been that 75% with 400 then 600 then 800 would be enough to progressivly remove the scratches from the previously used coarser grit.
I'd better start 'joining' my trial patches together or the boat will look like a measles case!
Thanks again