mikeschn wrote:Is there a water based spar urethane?
I heard someone used water based poly, and cleanup was nice and easy, but I don't remember if it was interior or exterior.
Mike...
Here's one:
http://www.admiraltymarinecoatings.com/varnish/varnish.html
Mike,
I am from the school that believes you can't get something for nothing. I like things that make life easier just like everybody, However I know from my personal experience that using the best finish coatings for the specific job no matter how much work and effort is required always pays off in the end.
My experience with clear coatings is mostly from small boat building. The number one thing that I learned early on is to avoid "Polyurethane" on anything that flexes and moves. I found it tends to crack easily, and is difficult to sand for recoat/repair.
The high quality traditional marine spar varnishes have good UV resistance, and don't crack from movement. They survive direct sun exposure, and most of all, are easy to sand and apply a fresh coat of UV protection.
All the modern coatings have their place, including PU, 2 part PU, and automotive clear coats. However, High quality marine spar varnishes and paints are designed for wood exposed to the elements with the least problems with recoating or repairing in the future.
Here's some info from a marine coatings supplier on the subject:
Choosing The Right Varnish
Quality marine varnishes fall into 2 basic categories, modern hard varnishes and traditional spar varnishes. The choice boils down to two main considerations: How stable is the wood you are coating? If it is prone to movement, such as a spar, old clinker, or carvel planked boat, traditional varnish is the right choice. If the piece is more stable and inert, a harder modern finish is also an option.
While modern finishes resist wear better, they are also harder to remove when you recoat. Some require strict temperatures and conditions for application that may not suit a boat out in the open. Traditional marine varnishes apply easily but typically have a longer cure time. Higher tung oil content provides a beautiful golden hue and that almost-wet appearing gloss. Traditional varnish builds on top of wood surface with minimal penetration, making it easiest to remove when the time comes.
Larry C