GP14 deck restoration

I've just purchased a solid GP14 but the deck requires restoration.

As I've removed the varnish from the foredeck there seems to be a difference in colour which I'm presuming is where water has got to the varnish. You can see the difference in the picture attached.

Can anybody recommend a way to ensure the colour is even before re-varnishing.

Is it as simple as having to sand back to original ply colour, is a wood bleacher required or is there something else I need to do?

Thanks in advance
Simon

 

I would chemically strip the plywood.
Then I would use oxalic acid to brighten the wood.
Oxalic acid will get rid of the grey. A hardware store will sell oxalic acid crystals. You mix with hot water and paint it on wood, you can also put a little dish soap into the solution.
Rinse it and examine how it look.
Maybe use a razor blade to scrape it, maybe a little fine grit light sanding
Sanding on plywood, well how thick is the veneer?

Most likely wood will need a stain applied for color.

Like this also DAP makes it.
Some wood deck bleaches are oxalic acid.
http://www.amazon.com/Savogran-10501-Wood-Bleach/dp/B002NZWY4A

 

In the UK I bought a Kg of oxalic acid crystals in Boots the chemist, ages ago.. Maybe they still sell it, if they don't someone else will. Best bet is to strip the varnish,sand WITH the grain even as coarse as 80 grit if the top veneer is 1mm, then oxalic and resand with finer say 180 with the grain again. If it is still not clear ie similar to the undamaged part, you may be better off painting it unless you wish to reveneer the top layer, or redeck.
If she's an oldish boat, she won't be competitive unless she can take near 190Kg (420 lb) rig tension without fuss.....and she is close in hull shape to the modern lines. As a reasonable family boat, might be better off to paint.

My experience of other 'bleachers' is extremely negative, but maybe someone else has found something better. Personally I don't like stain much over such large areas as it's moderately hard to get it really even without a spray gun and even with one can be a pain.

BTW a quick test to see the approx colour of varnish on wood is just to damp your finger with spit and wipe across the surface.

Regrettably the Montreal protocol has resulted in toothless paint strippers (ie no dichloromethanes) so finding one that works OK is quite tricky. There is a goodish Oz one from some guys in Poole if you search.

 

That's plywood and you'll never really get it fully clean, even with oxalic acid baths and sanding. Technically, you could sand down through the discoloration, making it all "fresh" raw wood, but in reality, you'll just sand through the top veneer on the plywood, before you actually get it clean and uniform.

Chemical strippers do work, even the biodegradable stuff, but they too can stain the wood a little. Simply put, it's plywood and generally this is painted, unless the outer veneer is book matched and/or sliced, not rotary peeled.

 

Many thanks for all your suggestions, I've already used a chemical stripper to get back to bare would and think I'll try the oxalic acid route and see where I go from there. I'll try and post some pictures post treatment.