Varnishing sapele decks

[MR Phantom Kipper]

Hi, I've got a question I hope I can pick the forums collective brains about - more of a dilemma really.

I've stripped back the decks on a 30 year old Merlin and sanded back as far as I dare to go on the sapele ply. I've put a couple of coats of SP Eposeal 300 on and it looks like it would benefit from another one or two to completely fill the grain. My next stage was going to be a coat or two of epoxy before 2 pack varnish - Perfection Plus - a process I've used before to good effect.

My dilemma is that I'm thinking about skipping the epoxy stage and going straight for the 2 pack varnish on top of the Eposeal as I'm a bit pushed for time and with enough Eposeal on to fill the grain, I cant really see what benefit the epoxy would have. I remember it adds a couple of days to the process working on evenings.

Any thoughts? The International Paint recommendations seem to be to go straight for the varnish after a few coats of their clear wood primer - which is similar to the Eposeal.

Any opinions / advice welcome!

[JimC]

An issue with Eposeal is that Gurit very firmly recommend you wait at least a week before overcoating with a solvent free epoxy because if every last bit of solvent hasn't gone from the eposeal very bad things can happen. So if you're pushed for time you'll save a lot by missing out the epoxy. I can't imagine you'll get anything like the thick film type effect you get with the solvent free epoxy in the middle though.

[MR Phantom Kipper]

Hi Jim, thanks for the information.
My original plan was to use SP106 which I've used before, which is still a solvent based epoxy (I think!) and then put the perfection 2 pack on top of that. I know SP320 is the recommended epoxy for clarity under varnish and is said to be less susceptible to UV degradation. I imagine that the non solvent epoxy traps the solvents beneath it which will probably end badly, where as I think the SP106 would be more likely to let the solvents through.

I'll go and look at the Eposeal / 106/Perfection + combination for compatibility.

[JimC]

SP106 ... which is still a solvent based epoxy (I think!)

Absolutely its not! Definitely solvent free.

[MR Phantom Kipper]

Ooops, that's an oversight on my part.

I've been on to Gurit, who were the most helpful company I've yet encountered - their advisor, Martin was superb. Apparently SP320 and SP106 provide an exceptional barrier layer so as Jim quite correctly identified, it is recommended to leave Eposeal for 7 -10 days so all of the solvent is gone before overcoating with either of the SP epoxies.

There is some light at the end of the tunnel though, as the PU varnish will allow the solvent to escape through, Eposeal can be overcoated with a 2 part PU varnish after only 12 -24 hours, which makes it the combination of choice for this project. I'l do the epoxy on top of Eposeal on the old Smokers which isn't such a rush job.

[Ed]

Varnish over Eposeal works well enough..... but my experience is that there are still potential issues with adhesion between the eposeal and the varnish.

For my money, I would leave as long as possible, then wash/sand/wash before varnishing.

Personally, I would use a trad singlepack varnish over the eposeal, but up to you.

oh....and personally, I wouldn't use 106 for coating. Great glue, OK for laminating, but not my choice for coating. It is just so hard to get a good finish on it. Possible with a heated and de-humidified workshop, but not easy otherwise.

eib

[MR Phantom Kipper]

Thanks Ed, its all got a little rushed and we need to use the boat in a week, so I figured 2 pack varnish would have cured more thoroughly by then as opposed to single pack. The original plan was to finish off with a couple of coats of Epiphanes but that may have to wait for a few weeks until we can take the boat out of service for a couple of weeks.
As far as the SP106 goes - I was told that the formulation had changed and the wax 'blush' was much worse on more recent batches, but I had a couple of Kg of it so that was as far as the thinking went.

I'll get as much key on the surface as I can for the varnish to adhere to - it sounds as though I've got a couple of heavy sanding days ahead - always tricky not to sand of everything that has been applied!
Thanks for the advice.

[chrismartin3583]

I have to say having done it on several boats i'm not sure that eposeal/320/varnish is necessary.

If going down the epoxy route i would rather apply 320 with a roller and aid penetration with a hot air gun. 3 coats, a thorough wash with hot, soapy water, flat back and varnish. It's really important to get ALL the shiny bits as this is where the fish eyes come from in the finish. It's also important to use fresh resin, old resin goes very, very waxy as the hardener is hydroscopic and no matter how careful you are once opened it will deteriorate.

If i had to use eposeal it would be three coats, scuff the top and apply varnish. Rather more coats of varnish that if i'd used 320.

I've never had an adhesion problem with eposeal. Not to day they don;t happen, i just haven't experienced this.

I must say that these days unless the wood is in very bad condition, i tend to not bother with epoxy and build up with very thin coats of two pack varnish primer - an equivalent product is probably the G4 pond sealer! At least this way you can actually get the stuff off again if you ever need to.

Coating with 106 - I don't know what they changed about 8 years ago, but it totally ruined what was otherwise a pretty good coating product. Stick with 320. Don't use old 106 for coating as it will be mega waxy by now and will probably go milky.

[Ed]

I must say that these days unless the wood is in very bad condition, i tend to not bother with epoxy and build up with very thin coats of two pack varnish primer - an equivalent product is probably the G4 pond sealer! At least this way you can actually get the stuff off again if you ever need to.

Agree totally.

Can't say about the SP105. It's many years since I stopped using it and moved over to Sicomin resins, which generally I get on with better, but never found it very easy to coat without using heat or a diluent.

eib