The spar varnish is typically used for boats because of its resistance to water. If you think that may be a problem - i.e., you have a very humid atmosphere in your home so there might be a chance of dripping from fogged windows. (yes, that can happen if you don't have the correct air movement in your home and the air outside is really cold even with double pane windows), I would use the clear satin spar varnish. The yellowing problem usually comes with a shellac finish that is usually applied for a quick finish. But I do think the pecan would be more prone to yellow because it has a yellow cast to begin with. Always sample first using the exact materials to be used for the final so you're happy once all the work is done. It is possible to customize stain colors just like paint if you go to the right paint store. I seem to remember we customized our finish when we used Anderson windows in a new build. It was a combination of a walnut and mahogany to give it more depth and then finished with a couple coats of poly satin after the sanding sealer. That's from 40 years of experience refinishing old and finishing new wood - even pine.

I have no expertise on finishes, but just want to predict that you are going to love your Marvin windows. We built a sunroom with eight of them, and they are the best windows we've ever had.

Feeny i'm sure I'll love my marvin windows - medium bronze exterior - they look awesome

carolannr - It's an old house with a really old furnace - i think condensation might be an issue until we put in a new furnace (and make sure it's properly adjusted). although in Chicago I think we'll get condensation in the cold no matter. I was looking at Man O War Spar varnish w/ UV protection to prevent the yellowing over time. Any experience with that product?

It has an amber cast out of the can.

The new home we built was in MN with the same humidity and cold. I really think I would go with a superior quality poly and at least a couple of final coats (with the sanding between coats) Its just one of those household maintenance things you will have to keep an eye on when you live in that climate - even painted window trim has a problem with moisture in that part of the country. The only spar varnish we ever used was for the extreme weathering on west facing front doors here in Colorado where a lot of people don't use storm doors so the wood is exposed to everything from 30 below to temps in the 100s and always extreme sun, rain and snow. It never does anything lightly out here The doors did yellow though and had to be re-done every couple of years. Good luck with your home - envy doing all that stuff again. My first house was a 100 yr old farmhouse moved into town. The bathroom was in the living room part of the old house, oil heat, old newspaper insulation, etc. Lots to do.

carolannr
any brand specific recommendations for a superior poly urethane satin finish? Googled the heck out of it and not finding anything except Minwax. help!

I would highly recommend a conversion varnish it won't yellow but a professional will need to spray the finish M.L Campbell makes a great product called Krystal

ms colours is the old masters their oil based or water based?

Rockin Fine Finish - my contractor hasn't mentioned spraying - i don't think that's an option. i think they do it by hand. any suggestions for a brush on?

Try fine paints of Europe like ms colours mentioned

bellycat do you have an update on what you chose and how it aged? 9 years later and I have the same dilemma!