I've used various water-based polyurethane varnishes for decades on furniture and interior trim. The few times I've used it for outdoor stuff it didn't last all that long.

Still, modern finish chemistry continues to amaze me with what they've achieved in solvent-free finishing materials. Afteer reading the TB Halcyon reviews over at JD I'd be willing to give it a try. I may order a quart just to do that though nothing needs varnishing - yet - among my kit.

The ease of use alone with waterbased varnish is enough to recommend them to casual users. If the outdoor longevity and UV resistance is up to what the reviews suggest the more serious end-user can expect I'd be willing to take the risk with a mind to getting some first-hand experience with the stuff.  

   Let’s see if I can give a measured assessment of Halcyon. Nope. Hate it.

Feels horrible coming off the brush. Looks horrible a year later, although it doesn’t appear to be failing. It’s colorless but not clear. If something can be muddy without color this is it. Ease of clean up doesn’t out weigh its ugliness for me. Its one saving grace is that it appears to be plenty tough. However, if you have a reaction to solvents it might be just the ticket.

I’ve tried many varnishes and have returned to Schooner 96.

Other folks, who have a lot of experience and offer sound advice have said they like it so this is just my personal experience. Your mileage will vary.

   Thanks, This is just what I am looking for. Fist hand experience with this product. Hopefully more people will weigh in on the subject. At first glance it seems like the positives would be to good to resist, fast recoat,no smell,etc but if the end result is not satisfing then it's not worth it. Thanks

Tom

System 3 makes a good water based clear polyurethane finish (I'll not call it varnish!). Very durable, at least with the optional cross linker.

And it's probably a matter of the learning curve (I've used it on only one boat), but I didn't get as smooth a finish. Humidity is critical, and perhaps I should have thinned it more. I didn't have good luck with their pigminted version. That might have been me. But I've heard from someone experienced that the clear was great, pigmented not so.

The clear doesn't yellow. Mine has been in use for 9 years now.

   I used TB Halcyon on a paddle board this winter. The board has only been used a few times this summer and stored indoors so I can't speak to how it will stand up to time, wear, and UV. I did want to chime in about surface quality and application. Because my project was a paddleboard there was a huge flat area to finish which allowed me to see every defect in the application. I had a lot of trouble achieving a flat, level finish. I tried cheap foam brushes, nice finish brushes, I applied a thin coat, I applied a thick coat, I applied thinned product, I applied unthinned, all had surface defects associated with self leveling. I finally figured out a method that yeilded a very nice level finish:

While the product is self leveling, it is intended to be applied quite thick (much thicker than solvent based varnish). If you don't apply thick enough you will see half leveled waves of brush marks even with full coverage. The application method I found to work best was to work in sections off of the wet edge and bush (cheap foam brush, I tried a nice finish brush but found the foam to work best) on quite a bit of product in one direction (overapply so it looks milky/cloudy). Then I would brush at a right angle to the originial application direction to evenly spread product on that section, I would then brush in the original direction again making sure the product was spread evenly and finally I would finish by brushing at a right angle from the original direction starting at the previous wet edge in full length, light tipping strokes. The key to a level finish for me was to overapply the product at first, and then remove product with the final tipping stroke pausing periodically to scrape extra product from the brush back into my container as I was tipping. So basically I overapplied, then tipped/removed to acheive a level surface.

I was able to acheive a very nice level finish with this method on my final 5th coat, although I did have to sand down the uneven ridges after the first 4 coats as I figured out this application method. I would use this product again because of its low toxicity, and ability to layer many coats in one day, but if it doesn't stand up to time, wear, and UV very well, I would move on.

Back some three decades ago my first exposure to waterborne finishes that I could trust was with a polyurethane varnish product from a company by the name of Hydrocote. In that it wasn't easy to find I lost track of it in favor of a similar Parks-branded product I could reliably source from the then new-to-my-area Home Depot.

On another forum this week I learned Hydrocote's still in business (still hard to find) offering a vastly expanded range of water-based finishes. Given my past experience I may seek them out once again, see how their products perform in this decade, if only above the waterline.