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Painting plastic cowls
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 Posted: 1 January 2010 05:04 pm
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martinw
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Has anyone got any tips for making Solarlac stick to plastic cowls?

I've tried Prymol and Spectra high build primer but both peel off after airbrushing the Solarlac on.

Airsail, who supplied the cowl, suggest sanding and Prymol as do Solarlac.

I sprayed the Lysander cowl with Spectra with no problems so presumably the Solarlac would seem to be the problem but I wanted to use it for colour match.

Any ideas :? 

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 Posted: 1 January 2010 07:58 pm
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Phil Fearn
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Hello Martin . It depends entirley on the type of  plastic . Try a small area that doesnt show and rub on some celulose thinners . If it attacks the plastic slightly then  the plastic is probably ABS and solalac will literally bond to it like **** to a blanket . If the plastic feels waxy it is probably polypropelene . paint wont stick to it without an adhesive . You can buy the adhesive in aerosols at Halfords or better still at BBS paint supplies on the Rochester City estate . Its still a bit hit and miss .A word of warning. Some of the cheap plastics that are used on models can be denatured by using cellulose and similar types of paint. The plastic will be fine for some time then will just break lke egg shell . Flair Wheels are an example . They should only be painted with enamel paint like humbrol. Also beware that some brands of Enamel like plasticote contain volatile thinners that will attack plastic . If al else fails use adhesive film and decorate it with that .

Best of luck and a happy new year

Phil

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 Posted: 1 January 2010 09:35 pm
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martinw
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Hi Phil Happy new year to you too

I've suffered from the Plasticote disease before - it didn't dry even after 2 weeks on primer!-and the cans went in the bin.

 I don't have any cellulose thinners but I just tried Solarlac thinners which smells like it and that seems to attack the surface of the plastic so it could be ABS. Should I spray the Solalac straight onto the unprimed surface now I've wet and dried back to the plastic.

The wing fillets, which I assume would be the same plastic, were brushed with several coats of Solalac and seem to be ok. The only real difference with the spraying is that it has 20% of thinners added.

Martin

ps   wouldn't it have been a lovely day for flying if we weren't waterlogged

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 Posted: 2 January 2010 10:27 pm
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NevLegg
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If you dust on the first coat on ABS with your airbrush, you should be able to use cellulose without any problems. I now stick to cellulose or enamel (Humbrol), having tried all the promised wonder finishes over the years, only to be dissatisfied in the end!

Cheers

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 Posted: 3 January 2010 05:41 pm
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Phil Fearn
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Hello Martin . Yes the reason I think its not etching into the plastic is that when you spray the paint the coat is so much thinner and dries before it can etch into the platic . Try a thin coat of car primer first . I coat all abs and fibre glass mouldings with a coat of primer as really adheres to the surface. de-grease the abs with a wash in warm water to remove any release agent left on rom the moulding process . dry thouroughly and abrade with fine wet and dry if needed . you can do that wet or dry but remember to remove any paticles before  applying a  thin coat of primer . I think they describe it as acrylic (solvent based) pimer now . this will take the sprayed Solarlac ok .

Regards

Phil

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 Posted: 4 January 2010 06:53 pm
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martinw
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Thanks for the advice Phil and Nev.

I'll give it a go

Martin

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 Posted: 4 January 2010 11:06 pm
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AdeH
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you could also try coating with etching primer Martin



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 Posted: 4 January 2010 11:27 pm
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martinw
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Hi Ade - the Prymol is supposed to be an etching primer but I failed miserably with it.

Do you have another name I could try?

This paint lark is quite a minefield. When I was working it was easy - Just send the job to the spray shop !!!

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 Posted: 5 January 2010 12:41 am
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AdeH
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Is it that sort of soapy (flexible) plastic they have used on the cowl?

I used Halfords etching primer once, that was ok, but it depends on the plastic you have got whether it will work.

Have you scuffed up the surface with a scotchbrite pad?

 



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 Posted: 5 January 2010 03:06 pm
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martinw
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For all intents it feels like ABS, but who knows - it,s made in New Zealand.

It comes in two halves so by the time you've filled the join and wet'n'dried, it's well scuffed up (that's apart from rubbing down after various attempts peeled off !!)

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 Posted: 5 January 2010 05:31 pm
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Phil Fearn
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Hi Martin . You say it comes in two halves . What  type of adhesive have you used to join it ?

Phil

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 Posted: 5 January 2010 08:15 pm
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martinw
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Hi Phil I used cyano and reinforced the join with plastic strips.

The kit suggested cyano or polystyrene cement.

Martin

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 Posted: 5 January 2010 10:25 pm
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AdeH
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I suggest using the current cowl as a mould and remaking a new one from fibre glass!

You could then make some for other poor sods who have the same problem!

 

Ade



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 Posted: 6 January 2010 07:06 pm
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martinw
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There is a company that do offer fibre glass cowls. Probably the problem has raised it head before.

I might get one before I spend a fortune on paint, wet'n'dry and eventually rub it down till its too thin to be any good.:(

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 Posted: 6 January 2010 07:29 pm
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Phil Fearn
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Sounds like ABS or polystyrene . Any celukose based paint should etch onto it ok . Have you tried a wet coat of primer . First coat applied as a sort of dust , ghost coat. Then shortly after apply a full wet coat . It should etch onto the plastic ok provided the release agent has been removed . Of course it could be made from re-cycled plastic milk bottles and nothing sticks to them :)

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 Posted: 7 January 2010 05:18 pm
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martinw
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Another abortive attempt :(

I think I'll order the fibreglass one before I kick the cat!

It's finished in gel coat. What's the best method of painting it???:?

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 Posted: 7 January 2010 05:45 pm
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Phil Fearn
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Gel coat is easy. Use 240 grit w/d on a block to remove any mould marks . Then remove 240 marks with 400 grit wet , then flat all over with 400 . Do it all wet and you you should remove all release agent from the surface . It ready when all the gloss has gone . . Dry thoroughly and dust off. On e coat with cellulose / acrylic primer . (solvent based acrylic not water based. Then vey light sand to remove any dust particles and colur with your choice of paint. cellulose/acrylic is best as it dries very quickly. Remove any masking while the paint is softand allow to cure for a day . If you want to put a clear coat over the top for added gloss then apply when the paint has dried for about 15 to 20 mins . That way the clear coat will adhere to the base coat and shouldn't flake off . Beware of too much paint as its very heavy. Hope it helps

Phil

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 Posted: 7 January 2010 05:49 pm
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martinw
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Cheers Phil.

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 Posted: 7 January 2010 07:15 pm
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AdeH
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Nice one Guys!

eventually got there!:dude:



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