I didn't know that water-based polyurethane was available as an alternative to oil-based until I saw it today at the store. I am refinishing a vintage stair banister and some surrounding trim. I wonder if I can expect equal (or better) outcomes if I use that or should go with the good old that has proven in the past in similar applications.
I've been prejudiced toward oil based polys for years, but having used water based polys on some projects that weren't all the important, I've been impressed. Water based is much less toxic, easier to clean up, more environmentally friendly and actually does a pretty good job. Seems to dry quicker and more solidly than oil based. It also seems to sand easily between coats. Being water based, it does tend to raise the grain on the first coat, but that's easily sanded down with fine sandpaper. I won't be using oil based poly anymore.
Because you used the word "vintage" I assume you care a little about the historic value and/or appearance of this, and while it's very much a matter of taste, I'd make a few recommendations:
- Water-based is much easier to work with and, unless it's for a floor, kitchen table, or such, I don't like using oil-based.
- Oil-based has a different look that you might find more "historical", and even more so if you use laquer or shellac instead of poly.
- Experiment on an inconspicuous area if you can.
- Join the Facebook Group "Historic Home Renovations". Post pictures there of your existing woodwork. Ask the question. The group is full of people who've done this many times and will recommend very specific products and brands (which is generally frowned on here).
I don't recall where I read this but oil-based polyurethane tends to build up gunk as the years go on. This is from humidity and people touching the finished product.
Apply 2 coats of oil first and then 1-2 coats of water for a durable gunk-free finish. I recently did this for some handrails and it came out great! Never apply in reverse; don't put oil poly on top of water poly.
Oil poly has always been revered as more durable so this gives you the best of both worlds.
Oil poly is useful for bringing out an amber glow in unstained wood.
The only downside of using just water poly is that if you don't stain the wood beforehand then it just has a cold and lifeless finish.
I refinished a bedroom floor 2 years ago and used 4 coats of water poly after staining and I really have no concerns about its durability.
If I have a choice I will always choose the water-based sealer over the oil-based one. Years ago when water-based polyurethane entered the market it may have not preformed as well compared to it's counterpart.
I've found it can't be differentiated from oil once it has cured. The sheen's are exactly the same.
There is less toxic VOC's from water-based sealer.
Water-based sealers dry quicker thereby allowing more coats in less time.
There easier to apply because their less viscous. They "level" better so brush strokes are less noticeable.
Lastly, they clean-up with soap and water. There's no need to wash your hands with petroleum-based cleaner.