Epoxy putty definitely holds up well, but honestly, I've had good luck with automotive body filler too. I had a job last summer replacing windows on an older house that had some pretty rough frames. Mixed up some body filler, pressed it into the holes, let it cure, then sanded and painted. It's held up surprisingly well through a full winter and summer cycle—no cracks or shrinkage yet. Might be another option if epoxy isn't handy or you're looking to save a few bucks.
"Mixed up some body filler, pressed it into the holes, let it cure, then sanded and painted. It's held up surprisingly well through a full winter and summer cycle—no cracks or shrinkage yet."
I've actually tried automotive body filler too, but my results were mixed. Last year I had to patch up some rotted spots around my garage windows, and initially, the filler seemed perfect—easy to shape and sanded down nicely. But after about a year and a half, I noticed slight hairline cracks forming around the edges. Nothing major, but enough to notice if you're looking closely.
Thinking back, I probably didn't prep the surface as thoroughly as I should've (lesson learned). Still, epoxy putty has been more forgiving for me overall... especially when dealing with wood that's exposed to weather extremes like we get here in the Midwest. I guess climate and prep work make a bigger difference than I realized at first.
I've had decent luck with automotive filler too, but I've found that sealing it afterward with a good primer makes a huge difference. Without primer, mine cracked pretty quickly... Midwest winters don't mess around. Epoxy putty is definitely more foolproof though.
Interesting point about the primer—I've definitely noticed similar issues in colder climates. One thing I'm curious about though, when you're using epoxy putty, how are you prepping the surface beforehand? I've found that even epoxy can fail if the surface isn't cleaned and roughed up properly. Usually, I'll sand down the area first, wipe it clean with acetone or alcohol, then apply the epoxy putty. After it cures, a quick sanding again and then primer seems to hold up pretty well. Have you tried any particular prep methods that made a noticeable difference for you? Always looking to refine my process...
"Usually, I'll sand down the area first, wipe it clean with acetone or alcohol, then apply the epoxy putty."
Pretty much what I do too, but I've found that using a wire brush after sanding really helps get into those tiny grooves and improves adhesion. Also, in colder weather, warming up the surface slightly with a heat gun beforehand (not too hot, just warm to touch) seems to make the epoxy bond stronger. Might be worth a shot if you haven't tried it yet...
Interesting point about warming the surface—I haven't tried that yet, but it makes sense. I've noticed epoxy can be finicky in colder temps. One thing I've wondered about though: does anyone find a noticeable difference between acetone and alcohol for cleaning? I've mostly stuck with alcohol because it's gentler on certain finishes, but maybe acetone gives a stronger bond? Curious if anyone's tested this out...
I've actually experimented quite a bit with both acetone and alcohol for window installs. Acetone definitely cuts through grease and oils faster, giving you a cleaner surface quicker. But you're right—it's harsher on finishes, especially painted or coated surfaces. Alcohol is gentler but sometimes leaves behind slight residues if you're not thorough. I tend to stick to alcohol on finished surfaces and acetone on bare metal or glass. Anyone else notice this?
I've noticed the same thing, acetone can be pretty aggressive. One trick I've found helpful is using alcohol first to remove most grime gently, then spot-cleaning stubborn areas with acetone—just gotta be careful around painted edges... learned that the hard way, haha.
"just gotta be careful around painted edges... learned that the hard way, haha."
Haha, been there myself—acetone can definitely bite back if you're not careful. Another thing I've found helpful is using painter's tape along the edges before applying any solvents. It takes a bit more prep time, but saves you from those "oops" moments later on. Also, microfiber cloths with alcohol usually handle most grime without needing acetone at all... less aggressive and safer for finishes.
Painter's tape is a lifesaver for sure, but honestly, I've found that careful scraping with a plastic putty knife can sometimes do the trick without needing solvents at all. Less risk of messing up finishes or paintwork. Also, speaking of smoother installs, has anyone tried using expanding foam specifically designed for windows? Heard it helps seal gaps better without warping frames... curious if it's actually worth the hype or just marketing fluff.