I have two Flex Seal products here.. one is the liquid, I've yet to open the container.. The other is Flex Seal Bright (White) Spray.. I bought it to insulate some wires I was working on, So far no complaints, they are not exposed to sunlight.. I also used it .. Well the story is kind of long but the windshield washer bottle on my car got damaged.. No leaks since applying multiple coats of Flex Seal.. I also have a 1" Sewer hose, The story here is I cut a foot or so off the end of my Free with purachase of a new motor home el-cheapo hose.. Put a female bayonet fitting on one end and the elbow to go into the ground on the other.. Well it developed some pin-hole leaks (These hoses often do) so I sprayed it with Flex Seal... So far, So good (that was 2 years ago)
never even considered it for the roof
Why
Brush on is black (Roof is white, and when i say Wite I mean that after I mop it in the spring and fall you need to take precautions against Snow Blindness if you are up there.. I kid you not. this is an 11.5 year old RV and the roof is still blinding white when cleaned)
The white stuff I"m told yellows fairly quickly.. I like that Snow Blind White.. Wish the rest of the RV was white (A/C works better, Furnace too when the RV is white or better yet silver)