Paint stripper on gel coat

[Dug1]

I'm halfway through the restoration of my Fantasie 19 yacht which before I took her on had lain untouched in a mud berth in Woodbridge for 12 to 15 years.
The hull is smeared with disfiguring brown paint marks over the original faded gel coat colour and my initial thought was that the hull would need to be painted to restore the hull to its former glory. Careful scraping with a palette knife over one of the larger patches of brown revealed to my surprise a shiny unfaded gel coat finish.
However progress was very slow and the thought of doing the whole hull with the scraper does not appeal not least the time required.
Has anyone had any experience of using paint stripper to rehelp remove paint from a fibreglass hull and if so was the gel coat finish affected? Any thoughts or advice on the subject would be welcome!

Doug

 

[KellysEye]

Interlux paint stripper is a specialist paint stripper for fibre glass and can strip paint off other surfaces.

 

[JumbleDuck]

I've had success using RemovALL 220 (intended for metal and brickwork) to strip GRP and abject failure in using RemovALL 620 (intended for GRP) to do the job.

 

[Avocet]

I've had very variable results with that. I once stripped all the paint off a fibreglass car with paint stripper and it was absolutely fine (and it wasn't the stuff specifically for fibreglass either). However, I also tried Nitromors on the varnish on Avocet's rubbing strake once and spilled a bit on the topside gelcoat. Within SECONDS it was bubbling!

I think the old "test an inconspicuous area first" adage would be the way to go. Depending on how thick the brown paint is, could you just hire a buffer and some aggressive buffing compound and simply buff it off while you're polishing the gelcoat at the same time?

 

[Plevier]

Do not use any stripper containing methylene chloride (aka methylene dichloride or dichloromethane). It will attack gelcoat severely. Yes I learned the hard way.
Nitromors used to contain this, it doesn't now, but some "professional only" ones still do.
If it's ordinary paint, caustic soda will do it well but is VERY nasty to use, cover up well with gauntlets, face mask etc.

 

[smth448]

Are you sure it is brown paint on the boat? If it has been in a mud berth for years it could be genral muck and oil that has slowly become ingained intot hte gelcoat.
If you scrape it off you will probably find that it has protected the gelcoat underneath from oxidisation caused by sunlight. so you will end up with patchy colouration on the boat. You may well have to paint it anyway to achieve a level finish.

As an aside, I just asked Mr Google about "Fantasie 19" and the first on the list was definitely NSFW!

 

[macnorton]

Why not use fine wet and dry and soapy water?

 

[Fantasie 19]

As an aside, I just asked Mr Google about "Fantasie 19" and the first on the list was definitely NSFW!

Steady - they are a subject dear to my heart.... This was my baby until I sold her last year...

Dug - feel free to pop over to the owners group on Yahoo http://groups.yahoo.com/group/Fantasie_19_Owners_Group/join

 

[JumbleDuck]

Steady - they are a subject dear to my heart.... This was my baby until I sold her last year...

On lives in my local marina ... in fact, I bought the mooring when her owner went soft. Very nice little thing.

 

[Dug1]

Are you sure it is brown paint on the boat? If it has been in a mud berth for years it could be genral muck and oil that has slowly become ingained intot hte gelcoat.
If you scrape it off you will probably find that it has protected the gelcoat underneath from oxidisation caused by sunlight. so you will end up with patchy colouration on the boat. You may well have to paint it anyway to achieve a level finish.

As an aside, I just asked Mr Google about "Fantasie 19" and the first on the list was definitely NSFW!

{:O) I'm not one to question the motives behind the designer's choice of names for his boat - especially on the PBO forum but it is odd how many appear to be named after ladies foundation garments, (for those of us with longer memories than most)!!!

 

[Dug1]

Many thanks for all the replies to this thread, all of the advice noted and followed up.
I did try both brake fluid and ordinary paint stripper (very carefully) with absolutely no effect on the 'paint' marking. so as already suggested it's not paint.
I 've gone back to dry scraping with a wallpaper knife and I'm finding clean and shiny unfaded gelcoat under the skin of brown marks also where there appears to be faded hull colour there it is a translucent similarly brittle but tough skin which when scraped reveals the full coloured and reflectively shiny gelcoat finish.
It won't wash off the hull - at least with nylon scouring pads and soapy water so I'm resigned to the slow but effective scrape using the corners of the blade technique - unless anyone knows better?!
It'll be worth it in the end.

Doug

 

[Asemaan]

Do not use any stripper containing methylene chloride (aka methylene dichloride or dichloromethane). It will attack gelcoat severely. Yes I learned the hard way.
Nitromors used to contain this, it doesn't now, but some "professional only" ones still do.
If it's ordinary paint, caustic soda will do it well but is VERY nasty to use, cover up well with gauntlets, face mask etc.

Hello Plevier,

We have just finished stripping old antifouling on a hull with GRP substrate using a paint remover that contains methylene chloride (Attached photo of composition), we noticed very few and small blisters in gel coat so we did some research and we came across your comment here. In most places the existing Gel Shield and gel coat was not affected by the paint remover, however in very few places where gelcoat was exposed and residue of the paint remover stayed for a while we noticed the blisters. What can you advise us to do? can we proceed with local gel coat repair in the damaged places and continue with additional coats of gel shield and new antifouling? or there should be additional steps to take in order to further protect the gel coat even in the places where it's not visibly damaged. We appreciate your response as we're planning on starting the painting process in the coming two days.

Alexa

 

[vyv_cox]

Hello Plevier,

We have just finished stripping old antifouling on a hull with GRP substrate using a paint remover that contains methylene chloride (Attached photo of composition), we noticed very few and small blisters in gel coat so we did some research and we came across your comment here. In most places the existing Gel Shield and gel coat was not affected by the paint remover, however in very few places where gelcoat was exposed and residue of the paint remover stayed for a while we noticed the blisters. What can you advise us to do? can we proceed with local gel coat repair in the damaged places and continue with additional coats of gel shield and new antifouling? or there should be additional steps to take in order to further protect the gel coat even in the places where it's not visibly damaged. We appreciate your response as we're planning on starting the painting process in the coming two days.

Alexa

I stripped paint off a grp deck using methylene chloride. It softened the gelcoat in places, sufficiently that I removed some of the non-slip surface during scraping. After some time there was no further sign of the softness and it seemed that it was back to its previous hardness. I think I could have repaired it with filler and gelcoat but my plan was to repaint it.