new to cvrda and need some help with my restoration project

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3279n12
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new to cvrda and need some help with my restoration project

Post by 3279n12 »

every time i try to get a coat of paint on the baggy trousers national 12, a few pieces of the hull veneer start bubbling up and delaminating. after the first coat i took these parts back to bare wood cut out the problem area and filled.

but iv now put a second coat on and its doing the same.

is this something im doing wrong? or is there anything i can do to fix it stop it happening again?

cheers
sam
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Ancient Geek
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Re: new to cvrda and need some help with my restoration project

Post by Ancient Geek »

Clearly some sort of Chemical Reaction!
"Most" Paint Manufacturers have helpful "Chemistry Departments" it may be hard to find the right number but when you get through the odds are they'' be "V Helpful".
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3279n12
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Re: new to cvrda and need some help with my restoration project

Post by 3279n12 »

ah ok thanks very much!


if its a chemical reaction, why would it be that its only effecting small areas on the hull?
if i leave it will it get worse as i add more coats or will it stay the same?

cheers
JimC
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Re: new to cvrda and need some help with my restoration project

Post by JimC »

What paint are you using?
3279n12
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Re: new to cvrda and need some help with my restoration project

Post by 3279n12 »

its a polyurethane based paint, usually used for larger boats, but apparently suitable for the 12.

it also did it with the first paint i tried which was international paints also a single pot paint
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Ancient Geek
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Re: new to cvrda and need some help with my restoration project

Post by Ancient Geek »

Back in the dark ages I had a similar problem with one part paints in those days in the Merlin Rocket Class we had Jimmy Ledwith a paint chemist, he suggested sealing the problem in with an aluminium based airplane paint. It did that and since I was painting the boat prior to selling it I did not bother to further investigate. Is it uncured resin or something?
As I said last night i wouls get the Paint Chemist on the case International especially have people who are paid to travel around looking at such things, report back and deliver the solution - if there is one!
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Ed
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Re: new to cvrda and need some help with my restoration project

Post by Ed »

mmmmmmmmmmmmmm

well I don't think this is a problem with the paint.

I think you have a hull where the top layer of laminate is coming unstuck and de-laminating.

When you put a paint on.....it is shrinking and pulling the laminate up.

Without the paint....the laminate stays in place and it is hard to tell what has lifted and what not.

The big question of course is what areas are affected and over how much area!

What do you do?

Not sure.....a hard one....

First a lot of careful research to see if you can tell what areas are affected.

How much area is currently affected?

What coating is currently on the boat...and the effected areas?

Clean as much off the bad areas as you can and a bit more and then:

I know some of this sounds awfull weird but....close your eyes and pull your fingers across the area....can you feel any raised bits? You do really need to concentrate on this.....then.....get a torch and shine it from the side so it 'rakes' over the surface, thowing shadows from any high points.....now run your fingers over, pressing down....can you see anything? You need to get your head right down so you are looking across the surface from close up as this will help to show you any movement. If you can't see anything.....wet the whole area down with water....not lots, but enough to wet out the surface. Leave till it starts to dry and then do the same. Water can also help on painted areas - if you have veneer cracking, as the water dries, there is a point where the surface has dried, but the water retained in the cracks has not. This will show cracks totally invisible to the naked eye.

Another technique.....equally likely to cause you to be taken away by the men in white coats.... is to get something hard like a screwdriver handle and try very gently knocking on an area you know to be 'bad' ....then a known 'good' area. There is normally (on Fairey boats it is quite noticeable) a different sound. Once you have got your ear in.....just go around tapping away until you get some idea of how wide the trouble is.

How do you fix it?

Depends on how much problem... and whether boat is varnished....and how much work you want to do.

Best fix of course would be to really find all the loose veneer and replace it all. You may well find this meant the whole hull, so be careful on going down this track.

2nd fix is to try and fix it in place. Many ways of doing this, it has been done a fair bit on 'loose' Fairey hulls. Basically, you want to try and inject some glue between the veneers. Basically you set a 1 or 1.5mm bit on a router with a depth of the distance to the inner join between the veneers. you then make a set of holes over a grid and drill the holes. You then have to inject some 'guck' in. What glue.....good question. again depends. If you use epoxy, you either need a fair amount of heat (and slow hardener), a very thin epoxy....or use a diluent (not sure this is good idea cos nowhere for it to evaporate to). Foaming Polyurethane glue is most probably a bad idea cos it may push the veneers apart. Last time I did this (on Fairey 14, I used) Blakes Woodseal Primer. Seemed to work well, but it was maybe more 'preventative' rather than fixing.

3rd fix is to be entirely pragmatic....if under paint....find bad places of lifting veneer and cut through them with scalpel down grain. Then saturate the whole thing in a good hard primer like (in my current preference) G4, Blakes Wood seal, UCP, SP300, thinned epoxy. Make sure it gets deep into any cracks....cuts....or loose bits. Any bits that show any evidence of lifting, drop a sheet of mylar or polythene sheeting over them and staple down through some thin ply. You can't do large areas like this as it may cause problems with evaporation from coating.

Which fix is easiest....and which right.....not sure depends on you, the boat and what you want to do.

hope this helps

eib
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Re: new to cvrda and need some help with my restoration project

Post by Garry R »

You are lucky that you are dealing with a painted hull and not varnish veneer as you will ultimately be hiding any repair. I agree with Ed as regards tapping the hull. Good stuff "rings true" and the lifted layer goes clunk!! It's then a scalpel job and lift the veneer and I found it was helpful to run a hairdryer over the area - gets moisture out and no scorching. Allow it to dry well. Than use West epoxy to inject into the gap and use a plastic sheet on top with a piece of ply or stiff cardboard with a staple gun. Remove the staples when set and fair the hull.
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Re: new to cvrda and need some help with my restoration project

Post by Rupert »

I had exactly this problem with the side tanks of the Europe in a couple of places. I came to the conclusion that the wood swells when you put varnish (well, G4 in this case) on it, and so any dodgy glue is forced apart. Agree with the scalpel and glue approach. Even varnished, if you go with the grain it looks ok till you get very close...
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