Onajourney wrote:tony.latham wrote:I use three coats of Minwax oil-based poly, which does an excellent job.
Tony
Tony - You recommend Oil based poly. Any downside to using water based poly?
Chris
Not Tony, but lots of experience with Poly/varnish on boats. The problem with most water-based polys is that they deteriorate quickly in UV light; i.e., sunlight. In addition, they are usually crystal clear so they don't bring out the grain and depth of color in wood. There are many oil-based varnishes/polyurethanes that are formulated to be UV resistant, and fare much better in outdoor applications. Check out a place like
https://www.defender.com/ for marine varnishes, and note they can be really expensive. The stuff you can get down at Home Depot, typically Minwax Helmsman varnish (
https://www.minwax.com/en/products/protective-finishes/indoor-outdoor-helmsman-spar-urethane) doesn't last as long, but may be OK for a teardrop that only sees several months of sun a year.
There have been a few water-based marine varnishes to appear on the market recently; here's one I've used:
https://www.totalboat.com/product/halcyon-marine-gloss-varnish/. The reports I've seen have been favorable with regard to longevity, but, be warned, I found it difficult to apply because it dries so quickly. It takes practice. Once you get the hang of it, though, you can produce a nice finish with 5-6 coats (in 2 days!). I've found that top-coating with a slower-drying water-based finish gives the best result, because the Halycon dries so quickly it doesn't have time to level out very well.