I've had similar doubts about Flex Seal myself. It seems handy for quick patches, but long-term durability—especially through harsh winters—is a different story. A couple years back, I tried it on a gutter seam that kept leaking. It held up fine through summer and fall, but once winter hit with freezing temps and ice buildup, the seal started cracking and peeling away. Pretty disappointing considering the hype.
Since then, I've experimented with a few other sealants. One that stood out was Dicor Lap Sealant—it's usually marketed for RV roofs, but honestly, it's been surprisingly effective on my metal roof edging. The key difference I noticed was in the prep work. Cleaning the surface thoroughly and applying a proper primer made a huge difference in adhesion and flexibility. Dicor stayed flexible enough to handle temperature swings without cracking or pulling away from the metal.
Another thing to consider is the type of metal you're sealing. Aluminum expands and contracts quite a bit with temperature changes, so you need something specifically designed to handle that movement. I've heard good things about Geocel Pro Flex too, though I haven't personally tried it yet. Anyone here have experience with that one?
In short, I think primer and prep definitely matter—probably more than the actual sealant brand itself. If you skip those steps, even the best sealants might fail prematurely.
- Tried Geocel Pro Flex last fall on aluminum flashing.
- Pretty solid stuff, held up well through winter freezes/thaws.
- Agree 100% on prep though... learned that lesson the hard way, lol.
Geocel's good stuff, used it myself when I redid some flashing around my chimney a couple summers ago. You're spot on about prep—had a buddy who skipped cleaning the metal properly, and the sealant peeled right off after a few months. Learned from his mistake, thankfully. Also found that applying it on a warmer day helps it flow and bond better... cold weather makes it a pain to work with. Glad yours held up through winter, though.
Good call on the warmer weather tip—I tackled my first flashing repair last fall, and it was definitely trickier than expected. I spent ages prepping the metal, scrubbing off old residue and grime with a wire brush, then wiping it down with acetone. Tedious, but worth it. Glad to hear yours held up through winter; gives me hope mine will too. Always reassuring when someone else's experience matches your own... makes me feel like I'm on the right track.
- Good prep work pays off big-time—acetone's great for that.
- Curious, did you apply a primer before sealing? Some skip it, but I've found it helps adhesion long-term.
- Always interesting hearing different methods...
