Varnish, Varnol, Coelan or what?

[johnchampion]

Most of my superstructure and cockpit is marine ply and has in the past been painted which I am not fond of as it offends the aesthetics and also hides any degeneration under it, so I intend to strip it off during the winter layup.
I see a lot of comment praising Coelan here but does anyone have experience of Varnol which sounds a lot more economic and also simpler to apply. Another option is something like Bonda Marine Seal, again if anyone has any experience of this product I would like to hear it. Of course if all else fails there's always good old fashioned varnish! Well new fashioned varnish really I suppose as they don't seem to make the old stuff any more.

 

[Mirelle]

I don't see any point in using Coelan over plywood; the merit of the stuff is its flexibility, as well as its durability, and ply does not move that much.

However, a word of caution - do a small test area first. If you are lucky, the paint will have been applied over varnish. If not, the primer coat of paint will have soaked into the grain of the outermost ply and when scraping this back to "clean" wood, prior to finishing it bright, you run a very big risk of going right through the outermost ply with the scraper. There is really no way out of that one - it will always look a mess. I would not like to attempt going back to a bright finish if the paint was applied to bare wood.

It is usually fairly easy to spot deterioration under paint - the paint ceases to adhere, at the spot where the damage is occurring. Scrape the paint off and have a good look.

 

[johnchampion]

I started to remove paint for the reason you say i.e there were some places where it was lifting. The original primer doesn't seem to have really soaked in to the surface and so far has been easy to remove in the small patches I've done.
The possible advantage I see to Coelan is that I understand it is "breathable" which at least gives the ply a chance if dampness does get in. Maybe that advantage alone is not worth the extra price.

 

[rogerthebodger]

I use this company's product as it is made for the South African Sun. I have used it on my yacht and at home in Johannesburg which is at 6000 fft above sea level and has very high UV.
The yellow coloured does give better UV protection but some say colour shows on some types of wood.
Don't know if available in UK but Email then and they may help.