Painting Plastic

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DanWood
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Post by DanWood » Wed Aug 17, 2005 10:12 am

Hi,

You've all provided help when I varnished a wooden boat, and I'm now wanting to paint an early 60's plastic finn.

Are there any special paints I should use or is International yacht paint the best?

Also, I want to fill and strengthen a couple of small parts, mainly where the mast goes through the deck - can I use the same epoxys I use on wooden boats to strengthen and seal this or are there more appropriate versions?

Thanks in advance,
Dan.

:?::?::?:

JimC
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Post by JimC » Fri Aug 19, 2005 9:39 pm

If there is no previous paint and you're really preparing the surface throughly I'd use two pot International: it won't need doing again for years. If there's already paint on that's not an option because the old stuff will fall off when the solvents in two-pot hit it.

DanWood
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Post by DanWood » Mon Aug 22, 2005 6:18 pm

Unfortunately, it already has a rather poor paint job - I'm thinking of sanding and re-painting, but not sure what I can and can't get away with on grp

Brian E. Evans
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Post by Brian E. Evans » Tue Aug 23, 2005 9:44 am

Dan
If the boat already has paint on it, you need to find out what that is. Or more correctly whether or not you can paint over it. Try the M.E.K. test, take a rag soaked in Methyl Ethyl Ketone and rub a spot on the paint. Keep the rag wet with MEK.Rub for about 10 mins.
Turn the rag constantly and watch to see if any of the paint comes off on the rag. If the paint does not come off, you can sand and prime, then top coat with any good two part polyurethane or epoxy paint system.
If the paint does come off on the rag then as Jim says you will have to remove it.
With regard to working on the deck The deck is most likely to be polyester resin You can use either polyester or epoxy for modifications.I do not know which epoxys you used on your wooden hulls. The West system is good as are Ciba resins or Shell resin systems. Which mod are you doing? are you removing the round hole and putting in the square hole with the nylon spacers?
General rule of thumb with polyester fiberglass hulls, if the structure is in good condition with no crazing, then sanding the surface with 220 grit paper and applying an epoxy primer followed by sanding to 320 grit then a good two part linear polyurethane will give you a finish that will last 10 to 12 years, stick with one manufacturer do not mix brands.
If you have spots that have the gel coat worn through exposing the bare fiberglass, build them up with resin and glass cloth and sand them smooth before applying your primer. Try to avoid using polyester body putty (Cataloy, Bondo)these things usually crack and craze due to movement of the hull and show up later spoiling your work.
I hope this will help. If it does not it will give Rupert and Ed some ammunition.Brian Evans.

Rupert
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Post by Rupert » Tue Aug 23, 2005 8:58 pm

I used International front door paint on the bottom of the ToY...It had several layers of not sure what on before, and I couldn't be bothered getting proper marine paint. DON'T use the wickes version, which I did on the decks coz they don't make yellow at international, it was horrible. The international went on great with a roller. Time will tell how will it lasts, but crashing it won't help the finish anyway!
Rupert

alan williams
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Post by alan williams » Tue Aug 23, 2005 9:20 pm

Hi Dan

You should use like with like as regards any fibre glass work on your boat. If your boat is built with epoxy use epoxy. However nearly all the old finns are built with polyester resin or vinylester resin. You should use this resin on your boat if built with this material as the bond will be better. Epoxy will give you no advantage and may even prove to be weaker. Remember to degrease the areas that require strengthing with actetone . If you can contact Scott Bader for advice (were Strand glass). If you are based anywhere near Plymouth Contact me through this website and I'll have alook for you.
Cheers Al Williams Finn340 GRP polyester Pearson

PS painted one of my cats (Nacra) with International Toplac using the correct primers and undercoats rubbed down with 400 wet and dry and final rub down with 800. Result was fantastic worth the cost of decent paint. Remember it,s the time put in to the preparation that gives the fantastic finish good brushes and painst help no end foam stick brushes very easy to use and give a brush mark free finish.

Rupert
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Post by Rupert » Tue Aug 30, 2005 8:59 pm

I agree with Alan on the Polyester/epoxy thing if adding more glass to the boat for stiffness anywhere. Filling is going to make little or no difference, so use the polyester as cheaper and probebly easier. If bonding bits of wood to the boat for stiffness or to put fittings on, I'd go for epoxy because it will bond to the wood, where polyester will crack away. Have to agree one gets a much better finish using flash paints than door gloss. Depends what use the boat will be put to after!
Rupert

DanWood
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Post by DanWood » Thu Sep 01, 2005 10:44 am

Many Thanks for all the suggestions.

I'll see how easily the esisting paint comes off and then take the best action.

I'm not too concerned about making a totally professional job that will last the next 35 years of the boats life, but just want it to make it look a little less shabby. Also I was concerned I might ruin the hulls structure if using things it doesn't like.

I've also got to replace the ply that covers the floor of the Finn for the sailor to sit on - does it have to be marine ply or is painted standard ply good enough?

Thanks,
Dan.

Rupert
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Post by Rupert » Thu Sep 01, 2005 12:25 pm

Ooh, another touchy subject where I'll be panned for saying that modern exterior ply will do the job!
Rupert

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neil
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Post by neil » Thu Sep 01, 2005 10:33 pm

before the IC worlds I split my sliding seat. I looked around for 4mm marine ply but could not find any, unless i imported it from Bristol (£65/sheet + delivery).

I ended up using 4mm exterior (£14/sheet), expoxied it both sides and slapped it on. The ply worked fine and withstood my heavy arse on it all week. OK it's not a pretty as expensive rotary cut mahogany ply but if it's painted or expoxied it should be fine. With the price saving you can replace it every few years and still be quids in.
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