No, the glass doesn't help block the sun IMO...I think it actually acts as a magnifying glass to degrade the wood quicker. This is especially true if your humidity level in the home is not set correctly, condensation forms on the glass and then runs onto the wood and gets cooked by the sun. Are your windows crankout style? Why does Sikkens say that you cannot use their finish on interior? I suspect it is because of the smell. It takes so long to dry, you would almost have to leave the house for a day to avoid the fumes. If the sashes are crankout style, I would still use the Sikkens finish and just leave the windows open all day...they will technically be outside drying. Or if they are double hungs, maybe take them off and finish them in the garage or something. You don't really need the UV inhibitors though. You won't win the battle against the sunshine without maintenance. I use a pretty cheap varnish made by ICI that holds up for at least 5 years. You can also use a Minwax poly that will be more durable.

I thought the UV was the main thing that would cause degradation of the surface (don't have a problem with condensation). Andersen claims its low-e glass filters out UV: "Ordinary dual-pane glass lets 62% of UV light pass through. Our High-Performance Low-E glass cuts that down to 17% with virtually no effect on the clarity and color of the light."

All but the one over the kitchen sink are double hung. I've already finished the casement window over the sink in the wipeon poly (wasn't much to do, skinny frames so I did it when I was doing jambs and stool).

"Sikkens does not recommend the use of any exterior products for interior use." They apparently make an interior Cetol but I'm wondering if it's any better than the poly I already have? It's probably $25/quart like the exterior stuff, so just wanted recommendations before I went and bought it.

I put 1 coat of the D&W on the garage window (same type as interior, bought it for looks since Andersen 200 series doesn't have the same grills as 400). It didn't go on as nicely as it did on the f/g door - I have brush marks. Brochure doesn't say to sand b/t coats but I think I'm going to - 320 grit? I plan on 3 coats. Even though they say don't use clear alone on high UV exposure areas, I think I can get away with it on this western window since the *interior* of the garage doesn't get much sun, so it would only be the areas on each sash where they meet, and maybe the bottom edge of the bottom sash. The interior faces don't actually get direct sun. It actually looked better than the one interior sash in the southern bay, and that's only the very bottom of the bottom sash that's looking dry anyway.

I did the slider with poly last year and it looks fine (eastern), the only problem with condensation is there, and it's between the wood and the glass where I can't even get to, you can see black on the edge looking in from outside, but nothing from inside. Andersen didn't seal the wood before putting the glass in.

The garage just has a screen in the upper window, so plenty of air (also full soffits) but it smells pretty bad.

"You won't win the battle against the sunshine without maintenance." So what do you recommend for finish on interior sashes, and how to maintain?

Thanks

Yeah, a lot of window makers have that thing where you can see raw wood from the outside looking in. I think it's stupid and a huge design flaw that nobody ever addresses. You can't seal that wood and they certainly don't so it turns black pretty quick. I would really just use the Minwax poly or Old Masters makes a pretty good poly too. And I don't know if the wipe on poly is any good because I've never tried it, but you do want film build. You acheive that with multiple even coats. I worry that the wipe on poly is thinned so that it can be wiped on without it puddling up, but that is just a guess. More coats means thicker coating which means that the sun will take longer to eat through it and get to the stain. By maintenance, I just mean that you need to apply another coat every 1-3 years just on the sashes where the wood gets direct sunlight. You don't want to let them get black or worn or water stained because it is very hard to sand/repair wood that is butted right up against glass.

I know - we had horrible single pane windows with an inset storm (house built in 1987) on our old house, had problems with condensation every winter and tried to sand/poly those - the house was 8 years old when we bought and the wood was already damaged.

Andersen claims they use a "wood preservative" on their products, but if the black gets worse I'm going to call in their warranty on the slider and see what they say.

The wipeon poly is really thin but then I don't have to worry about brush marks :-) and it goes on nice and even. I put 3 coats on jambs and stools, can always add more if it looks like they need it. I put 6 coats on the bathroom door (3 coats all sides of the baseboard and window trim right before I put it up). I think I'll just stick with that. Take a little steel wool to them between each coat. I think 3 coats of wipeon would be same as 1-2 brushed on. I can put more on the jambs soon if that's too little, was just trying to get *all* the windows done with *something* ASAP. Since I was doing them in place it really isn't any harder to add more later. Now the sashes I'm going to do out of the frames, so will do all of the initial coats while they're out - only takes a couple hours b/t coats. So is 3 OK to start, and add more in the areas that get more sun each year, or should I just do 5-6 coats over the whole sash now?

Do I have to stain? I didn't stain all the jambs (well, except the 3 bay windows - that was a mistake b/c the gel gunked up in the corners, I had forgotten I hadn't stained the slider in that room, I did the windows right after I did the kitchen window that needed more color). I hit a few spots in the kids' rooms with gel stain just to even out the color a bit if one jamb was redder than the other. Can I do the same with the sashes or is it better to put a really light coat of gel (and wipe well out of the joints) over the whole thing? If the stain doesn't do anything to help protect the wood (or keep the color consistent as the window is exposed to UV) then I won't bother to do it b/c that adds 24 hours to finishing time, besides being hard to get out of the joints.

Thanks for all your help.

I would do however many coats it takes to get a nice even film build on the sashes. No, you don't have to stain. People finish their trim natural all the time without staining.