How to finish the deck

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How to finish the deck

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25 May 2010 at 21:36 #1965
Jeremy
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@jeremy15845
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25 May 2010 at 21:36 #26914
Jeremy
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@jeremy15845
Above is a photo of the deck of my Mantua Bruma – alternate strips of lime wood and oak. I have given it 3 coats of cellolose sanding sealer, sanding down after the first two coats. Now what?

Do I sand down the third coat and leave as is or should I varnish on top of the sanding sealer? If it should be varnished, can I use a spray can of Humbrol acrylic varnish in either gloss or satin finish (I have both)? If not either of these, what would be right? Expert advice would be appreciated.

Jeremy
25 May 2010 at 22:43 #26915
neil hp
Participant
@neilhp
i normally rub my sealed timbers down with a fine grade wire wool..doesn’t scratch the grain. then varnish over the sanding sealer with a good deck varnish.

neil
26 May 2010 at 00:23 #26917
Charles Oates
Participant
@charlesoates31738
Hi jeremy and Neil,

What a beautiful deck, a smashing piece of work that is. As to the finish, putting a varnish over a cellulose base wories me, the cellulose may act as a solvent to the varnish and ruin the deck. Cellulose can remain in the wood for quite a time.If you are thinking of trying this I would prepare a separate piece of wood with sanding sealer and then varnish over that. leave it for some time and see if all is well, hopefully it will be but it is better to be safe than sorry. If the test fails I would investigate a cellulose varnish from a motor factors, and also test that first. Usual best practice is not to mix solvent bases in the finishes you use.

I’m not sure about acrylic finishes over that base, perhaps someone else will know that one.

Charlie.
26 May 2010 at 08:35 #26919
neil hp
Participant
@neilhp
There’s no problem putting an oil based finish on top of a cellulose, Charles. the problem comes when you put a cellulose on top of an oil based cover.

They “dry” through different mechanisms……oil based coverings such as polyurithane and enamel varnishes”cure”, they get harder and dry in that way.

cellulose based( same as acrylic) paints “dry” through evaporation of the solvent, and it is this that will “orange peel” any covering that it goes onto such as cured varnish. It tends to grab at the under surface and “picks” it off the surface as the solvent evaporates.
27 May 2010 at 08:58 #26941
Charles Oates
Participant
@charlesoates31738
Hi Neil,

thanks for the info on acrylics, I have only used them for 18 months or so and I am still getting used to them. I raised the doubt about varnish over celulose because of a problem I had some 20 years ago. I had sealed a hull (balsa) and painted over it the next say with enamels. After a week or two the paint started crazing and lifting. I’m pretty sure that there was still some celulose left in the wood as the effect was identical to what too many of us have seen if we put celulose over enamel. This was probably because of the porosity of balsa and the short time I left before painting. I now seal decks ( or balsa) with thinned varnish.

After looking at the smashing job Jeremy has done with his deck, I thought it only fair to raise the doubt, It would be rotten if he was as unlucky as me. Acrylics might be the safest for Jeremy to use, I used to have doubts about them but my recent experience with acrylic varnish has left me a fan of it.

Charlie.
27 May 2010 at 10:00 #26944
neil hp
Participant
@neilhp
No problems, CharlIe….and you are right to tell us.

No one is infallible, and I for one am learning all the time.

Only the pompous, stubborn or self opinionated think that they can’t learn from others,and won’t accept constructive criticism.

I haven’t worked with balsa for more than 45 years,and so am no expert in painting the stuff, and you might be right that pockets of sealer hadn’t dried if multi layers had been put on top of others that hadn’t dried yet.

Painting can be a risky business if you mix the medium.

However two things that comes out of this are, make sure that the paints are dry before putting another paint on top, and we are never too old to learn.

neil.
27 May 2010 at 16:40 #26954
Jeremy
Participant
@jeremy15845
Hi Charles and Neil

Thanks for the advice – I’ll have a go with the acrylic varnish. The cellulose has had ample time to dry out. If I run into trouble, I can always sand it down. Now the question is which acrylic should I use, the gloss or the satin? I have both at hand.

Jeremy
27 May 2010 at 20:59 #26960
ashley needham
Participant
@ashleyneedham69188
I am not sure as the long term resistance to water for Acrylic varnishes, however on the basis that the deck will only be getting the odd splash now and then i suppose it would be oK…do they do “exterior” Acrylic varnish?

I have never had a problem with Celly sanding sealer lifting paint. If the day is at all warm, 20 minutes should do before overpainting can commence, it dries very rapidly (assuming thin coats and no pooling . i am usually in a rush to get things done and rarely leave the stuff to dry for longer than 10 mins .

Also..poly varnish will tend to yellow after a long while, whereas Acrylic will remain clear, but nothing beats the shine of Poly. AND after all, its what most “real” boats use?

Question is…do you want a glossy deck or a flat deck? realistically the deck on a real boat would be sealed and not varnished? But looking at the job you have done, It deserves a nice shine. I think its up to you, any modern finish will be ok, just depends on what you fancy.

Ashley
27 May 2010 at 21:04 #26961
Charles Oates
Participant
@charlesoates31738
Hi Jeremy,

Gloss or satin? It’s all down to personel preference. I’d go for satin because I believe that on Bruma ( a beautifull design in my eyes) it would create a much better rendition of the real thing. My only extra advice is to take your time, rub down well between coats and clean the surface before each coat. Many of us have looked at our models anfd thought ‘if only I had taken a bit more care’ I’m still doing it! it’s part of the learning curve that Niel was talking about.

Neil, I agree completly, It sounds as though we both started around the same time. For me the learning is as much fun as the acheivment, and most of my more recent mistakes are too embarasing to mention, but I nearly put a handrail across a doorway on the Pereja I’m building. Oops.

Charlie
27 May 2010 at 21:52 #26962
neil hp
Participant
@neilhp
i have a notice standing proud in my workshop for when i’m moulding in grp.

which reads “don’t forget the hardener, you silly tosser”……..

self explanatory why, really.lol
27 May 2010 at 21:54 #26963
Jeremy
Participant
@jeremy15845
Hi Guys

Decision made! I’ll go for satin acrylic – the slighly dulled finish will mask the imperfections better than hi-gloss. Thanks for the input.

On a broader issue, I would appreciate your advice on how best to use the forum on this site.

Either , as I come up with a question or problem at any stage of construction, I can start a thread as I did on this occasion and did previously on a waterproofing problem with my Nordkap. This may be the most direct way of getting the advice needed.

Or, I could start a build log and seek advice on the way. A build log would give more continuity and maybe help others who are building the same boat. When I was building Nordkap which was my first effort, I found a build log on another site very helpful in comparing problems and solutions with other people who had built or were building the same model.

What do you think?

Jeremy
27 May 2010 at 23:42 #26966
Peter Fitness
Participant
@peterfitness34857
Ashley, to answer your question about “exterior” acrylic varnish – it is available, at least it is here in Australia, and I have used it with success on boat hulls.

Peter.
28 May 2010 at 08:36 #26971
Charles Oates
Participant
@charlesoates31738
Hi Ashley,

I’ve finished 2 hulls with acrylic, 1, 18 months ago, 1, 4 months back. Niether has shown any problems. I understand that the stuff has been developed somewhat since it first appeared. It was similar doubts that made me hesitate before I started using it, now I rather like it, but I still like poly if I need a high gloss finish.

Jeremy, my vote is for a build log, just because I enjoy reading them.

Charlie
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