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Author Topic: Finishing/Waterproofing help please  (Read 4098 times)

CJ

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Finishing/Waterproofing help please
« on: January 10, 2012, 02:15:55 PM »

Hi,

In anticipation of being welcomed into your circle of great knowledge, I am hoping someone with far more experience than I have could possibly assist me with a problem.....

I have inherited my Grandad's scratch built rc Fairmile B class modelled on the craft he fought on during the war......no longer with us and some 13 years old I have restored very slowly over the last 4 months  :}  - still a bit to go but not too far now.

The hull was all finished, repainted in red oxide below the water line, hand painted in dulux matt satinwood above and white acrylic spray marking at the front, porthole detailing finished in enamels. Now I know the paint types may not suit all but I have tried to restore what was done previous so please bear with me.

Decals finally turned up over xmas and were placed on and over the holiday period I coated with Ronseal Clear Matt Satin Varnish.....woke up the next day and  >>:-( >>:-( flippin boat had turned yellow. Now upon reading the small print the clear non darkening varnish apparently "may darken as is tinted". Oh and I did try a test patch too !!

Anyway, 2 weeks of sanding, repainting, redetailing and awaiting new decals to turn up I am pondering the best solution to "finish/waterproof" her, I have looked at acrylic spray varnishes and various posts on this excellent forum but would love for someone with a bit more knowledge to advise what they think would be best.

Funny enough I do not fancy another ruined attempt - and in readyness have a sample board painted with these paints to try again.

Any help would be very much appreciated.

CJ
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Welsh Wizard

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Re: Finishing/Waterproofing help please
« Reply #1 on: January 10, 2012, 06:05:09 PM »

Welcome to the Madhouse and hope you enjoy yourself here,plenty of experts and someone will help doesn't matter what the subjct is.
One problem you have got is that MOST varnishes will turn Yellow in time but to happen instantly WOW.What I personally would do is to try Plasticoat Lacquer available form B&Q Halfords etc Be WARNED if getting it form Halfords that you don't buy their clear lacquer as it will react with your paints.Plasticoat is basically an enamel do shouldn't react.PLEASE PLEASE PLEASE don't blame ME if it does try a test Piece first.Although I am a Qualified Paint sprayer Varnishes are NOT my strong point I will freely admit that BUT there are plenty of members who will help,bear one thing in mind it might work for me or them BUT !!!!!
All the best


Dave
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CJ

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Re: Finishing/Waterproofing help please
« Reply #2 on: January 10, 2012, 06:40:50 PM »

Dave,
Many Thanks for the post  :-), good advice that I am sure I have read elsewhere here and was thinking of testing that out. Don't worry, will never blame anyone for their advice....that is what I came here asking for and more than happy to listen to anybody with experiences to share. And yes I have a test piece of wood lined up and ready to go before I even think of going near the hull again  :-) !!

Will try and get a an tomorrow and have noted to avoid the clear lacquer !!

CJ
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john s 2

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Re: Finishing/Waterproofing help please
« Reply #3 on: January 10, 2012, 07:14:04 PM »

Ive sadly found out the hard way that on a boat only one area may pickle etc. So even with a test piece i wish you luck.John.
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DickyD

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Re: Finishing/Waterproofing help please
« Reply #4 on: January 10, 2012, 07:22:41 PM »

Why varnish at all, it only does the same job as the paint ?

I have made 19 boats none of which has been varnished except when I needed a matt finish and the only paint I could obtain was gloss. :-))
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Richard Solent Radio Controlled Model Boat Club http://www.srcmbc.org.uk

barriew

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Re: Finishing/Waterproofing help please
« Reply #5 on: January 10, 2012, 08:15:53 PM »

Richard,

With the assortment of different paint types on the model, I think the varnish is desirabe to give a uniform finish - also not too sure how waterproof the Dulux Satinwood wil be ;)

Barrie
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DickyD

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Re: Finishing/Waterproofing help please
« Reply #6 on: January 10, 2012, 09:08:53 PM »

Use exterior paint Barrie.  :-))
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Richard Solent Radio Controlled Model Boat Club http://www.srcmbc.org.uk

CJ

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Re: Finishing/Waterproofing help please
« Reply #7 on: January 10, 2012, 11:13:19 PM »

Thanks for the tips guys, Yes I agree that exterior paint would be ideal however as inherited and being restored the satinwood is a needs must unfortunately.....I "assumed" (great word that) that clear varnish would finish it nicely however clearly not the case!!
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Colin Bishop

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Re: Finishing/Waterproofing help please
« Reply #8 on: January 10, 2012, 11:34:33 PM »

I think you will find that Ronseal Polyurethane matt or satin varnish (not the quick drying variety) will give you the result that you want. Use the interior variety as the external version contains UV filters which give a slightly  yellowish tint, I assume this is what you used before. I have found that it goes on OK over almost any finish as long as it is properly dry.

Rustins, Blackfriars and Wilkinsons do similar products but do make sure you get the polyurethane variety. The quickdry stuff is acrylic and isn't really suitable.

Colin
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CJ

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Re: Finishing/Waterproofing help please
« Reply #9 on: January 11, 2012, 11:25:31 AM »

Thanks Colin, yes you are correct it was the external version I used, assuming waterproof was better for the boat !! Will give this a test trial too, I am assuming it repels water well ?

When you varnish do you thin at all ??

Many Thanks
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Colin Bishop

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Re: Finishing/Waterproofing help please
« Reply #10 on: January 11, 2012, 12:36:18 PM »

The only difference between the interior and exterior versions is that the latter contains the UV inhibitors which resist damage from the sun and at the same time give a slight yellow cast which is particularly noticeable over lighter paint colours. Both are equally hard, durable and effectively waterproof. (yacht varnish is similar to external varnish in some respects with an even yellower tint and is also slightly flexible - don't use it over painted surfaces). The interior version is perfectly OK for models as you are not going to leave them outdoors in all weathers and probably 90% of their time will be spent indoors!

If you use Ronseal as it come out of the tin with a flat artists brush it will go on pretty well but people who use it regularly reckon that a bit of thinning doesn't do any harm as long as you don't put too thick a coat on as you may then get runs.

If using an airbrush, Model Boats editor Paul Freshney who achieves superb finishes on his models, thins it 4 parts thinner to one of varnish and puts on several coats but if using a brush I would just thin it enough to ensure that you don't get runs when brushing on a thin coat and be prepared to put on a second coat if necessary.
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CJ

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Re: Finishing/Waterproofing help please
« Reply #11 on: January 11, 2012, 06:07:34 PM »

Thank You again Colin, will definitely give that a trial and see how it goes...will let you know, as long as she sails OK and doesn't leak I think I prefer the idea of varnish !!

 :}

CJ
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Colin Bishop

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Re: Finishing/Waterproofing help please
« Reply #12 on: January 11, 2012, 06:28:48 PM »

Do bear in mind that any 'transparent' coating applied over a paint finish will result in a degree of darkening so the thinner the coat the better.

Colin
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CJ

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Re: Finishing/Waterproofing help please
« Reply #13 on: January 11, 2012, 06:30:43 PM »

 :} noted Colin - thank you !

Determined not to have a repeat performance !!
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CJ

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Re: Finishing/Waterproofing help please
« Reply #14 on: January 17, 2012, 02:21:14 PM »

Colin,

Just wanted to thank again - coat finally put on and dried and worked a treat - thank you all for your help and pointers.  :-)

CJ
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Colin Bishop

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Re: Finishing/Waterproofing help please
« Reply #15 on: January 17, 2012, 03:26:10 PM »

Glad it worked OK, just about to paint one of mine now!

Colin
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bobk

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Re: Finishing/Waterproofing help please
« Reply #16 on: January 17, 2012, 04:59:16 PM »

Just been to B&Q.  Got a tin of Ronseal Polyurethane interior satin varnish, plus a can of Plasti-kote Polyurethane Varnish Spray Satin.  Ronseal spec says to use white spirit as thinners. I will run some test pieces first.  Thank you !
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CJ

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Re: Finishing/Waterproofing help please
« Reply #17 on: January 17, 2012, 09:45:30 PM »

Bob,
Best of luck with it, but yes do run some test pieces first.....learnt the hard way  :(( !!
Worked well for me, on matt satinwood, gloss, enamel and acrylic paints and over decals too  %)

Hope you get the result you want, all the best.

CJ
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Colin Bishop

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Re: Finishing/Waterproofing help please
« Reply #18 on: January 17, 2012, 09:49:09 PM »

The Plasticote may well be OK, it's just that you can never be sure of the effect of the solvent used in cans, but a test piece should indicate if there is likely to be any problems.

Colin
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bobk

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Re: Finishing/Waterproofing help please
« Reply #19 on: January 17, 2012, 10:38:41 PM »

Understood Colin.  I will paint up some samples in similar materials using the paints I am using, then when fully dry try out both varnish types.  Of course there is always risk, depending on numerous variables, but at least I feel I have a better understanding and have probably reduced the more obvious pitfalls that others have found through long experience.
Wonderful things model boats.  At least Mayhem helps shorten the trial and error learning curve   O0
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