Deck Re-Finish

What would be the best method to repair this mahogany with balsa seam deck?

Previous finish has adhered well to planking but has lifted off balsa seams.

I'm thinking THAT sanding off the existing coat and re-coating with high UV block 2 pack PU would be the best choice.

Dino

 

Strange, the balsa (and why soft balsa rather than a harder light wood (holly, ash, etc.,e.g.)?
I guess if I were you I'd experiment. I'd try a small brush on a seam after removing the lifted varnish and scrubbing with a 3m pad loaded with some alcohol. Use a brush not too much more than a half inch wide. Paint a section of seam a few inches long with varnish and let it dry, making sure the stuff is sticking this time. Then add six to eight (depending on thickness of coat over the planks) more coats just on the seams before finally sanding the whole deck with 220 grit. Get it all level. Now add a couple or more coats to the whole deck.
In my experience, a two-part varnish isn't well suited to your situation. For a novice, the urethane stuff is trickier to work with, is toxic, and expensive. Also, regular varnish is more practical on broad surfaces where re-coating is a snap. Two part is best done by a pro.

 

Hi Dino, are you sure those seams area balsa? It looks like the varnish/poly has lifted off the caulk seams, which typically are single or two pack polyurethane. Also holly, ash and oak are the usual choices for this type of deck treatment (inlay), though often only inside the boat. It's tough to make an inlayed deck stay put in Florida. The best way is to use the same species, but stain one of them for contrast. Last;y, I wouldn't use a 2 pack LPU on this stuff as it's not flexible enough to cope with the movement and is a ***** to repair when it comes time. A high quality varnish is my recommendation, unless the boat will be stored indoors, kept dry, etc. If this is the case, I'd recommend "Bristol Finish", which you can get over near Vero beach. It's still a ***** to repair, but if stored indoors, you'll not have to worry about it for a long time.

 

Alan and Paul,

Thanks for your interest. The boat is in Greece which I will sight in 5 days.
The first question I asked was if they were sure it was balsa. The second was if the coating was 2pack PU or classic varnish. They are 99% sure it is balsa because they are also aeromodelers. They think it is 2pack but I will do a nitro thinner test on it to confirm if it dissolves.

My thoughts are mixed. At first I thought 2pack because of durability and abrasion resistance. Now I lean more towards Epifanes clear coat which is a tung oil based, phenolic modified alkyd resin varnish and seems to be the gold standard for conventional marine spar varnishes.

Durability and hardness would be at the expense of flexibility which should be the priority given the performance of the previous coating.


Dino

 

And the decision is:





Old 2 pack PU removed, oxalic acid scrub then Epifanes clear coat tung oil varnish. Wood strips are holly

Dino

 

Two part varnish is hard and brittle. As the deck moves the varnish cracks. Not a good chpoice for a deck.

One part varnish is flexible.

Epifane is a top class high solids varnish. Very resistant to UV damage. Build up a good film thickness and it should last for many years.

When using Epifanes varnish this accelerator should be in your bag of tricks. Good to speed cure for sanding and recoating and to avoid dust on the finish coat

https://epifanes.com/na/store/thinners-additives/accelerator-for-paint-and-varnish/