Thread: Varnish

Originally Posted by teasea

I am finishing a strip built kayak and am up to the varnish stage can any one advise please if the range of Feast Watson marine varnishes are compatable with the Bote cote expoxy system as they are a quarter of the price. Obviously bote cote support there product, but a saving is a saving, but only if it works.

I've used the Feast Watson marine varnish over epoxy. No problems, provided you wash the epoxy coating well with water first. However, you should know that FW is a "softer" formulation and doesn't dry very hard like some others and so maybe don't use it where it will take some scuffing and knocks.

Varnishes do not stick well to epoxies as they have a tendancy to peel and scratch quite easily. Another point is your money saving will only be a temporary fix as it will go to custard after 12 months without fail then you've got to sand it back and do it again.

I used a Cabot's varnish on my ply kayak about this time of year in 2009 - think it was sold as a marine varnish but I'm not 100% sure (will check tonight if I can remember). It has not had a huge amount of use but I have logged about 40 hours paddling time and so far it has stood up well. Can't see it needing a refinish anytime soon although I have been careful with it. I imagine that most single pack varnishes from reputable companies would be similar.

The important thing with epoxy is to use a varnish with UV inhibitors as this is what breaks the epoxy down. There are comparisons between single and 2 pack coating around but they boil down to 2 pack lasting longer against the single pack being easier to apply.

My choice is single pack but it's a matter of personal preference (equipment and skill level are probably factors here and I have neither )

Scott, I'm not sure of your experience, but traditional varnishes stick very well to epoxy. The ability of alkyd varnishes to stick is the exact same way as paints and assuming proper surface prep will preform well.

Softer varnish formulations are usually intended for surfaces with movement, like wood, so an epoxy encapsulated piece wouldn't be be best served with a soft varnish formulation, but it should stick to the epoxy fine, given proper prep.

The choice of polyurethanes, LPU's and alkyd varnishes all have good and bad points to consider. LPU's can't be repaired if you let them go too long. The polyurethanes as a rule can be touched up, but it's a small window before you're screwed and have to start over. Alkyd varnishes on the other hand, can be repaired over a much wider range of neglect and can usually tolerate much more elongation, distortion and movement then the synthetics. The trade off is durability, with varnishes being the first to break down and the LPU's the last.

Originally Posted by Scott-DMS

Varnishes do not stick well to epoxies as they have a tendancy to peel and scratch quite easily. Another point is your money saving will only be a temporary fix as it will go to custard after 12 months without fail then you've got to sand it back and do it again.

This is only true if you have not followed the instructions of the epoxy manufacturer and removed the wax by product of the epoxy cure.

Do that properly and you won't have any problems with varnish over epoxy, which of course is essential in order to achieve a UV stable finish.

EDIT: I hadn't read PAR's post before I wrote this, so yes, we agree that varnishes over epoxy are fine. I should have mentioned the most well known proof of the success of this type of finish on this forum, namely Gruff, Bitingmidges 16y/o GIS
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I have used International "Goldspar" varnish over Bote Cote epoxy several times and had no problems at all. Goldspar is a single pack polyurethane, seems to have good UV resistance and is quite easy to apply.

No experience with Feast Watson sorry, to go back to the original question.

Cheers, Cameron.