Which Spray Sealant Brand Wins?
We compared 3 spray sealant options head to head. Flex Seal came out on top. See the measured results, the runner-up, the budget pick, and a link to the full test video.
Flex Seal
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The measured results
Every number below is read straight from the test. Scroll sideways to see all measurements. Products are listed in the order they finished.
| Product | Cure time required | Cut bucket leak test | Bucket structural pull/strength test | PVC-over-metal-pipe structural break test | PVC underwater pressure test | Scratch/adhesion to PVC test | Metal air tank underwater pressure test |
|---|---|---|---|---|---|---|---|
| 1Flex Seal | needed the longest cure time of the three products; narrator allowed 70 hours instead of the required 48 to be safe | the only one of the three products that actually worked and held water; no air gaps visible in the crack, though the coat looked thinner than Perma-Seal's | took quite a bit of force to fail; narrator felt a couple more coats would have prevented tearing entirely | included in this test but no spoken comparative outcome/measurement was given in the transcript | not explicitly called out failing at a specific PSI in the transcript; Rustoleum was the only one confirmed still holding at the higher pressure readings | seemed pretty good visually but did not stick to the PVC very well, easy to scratch off | started leaking at about 2 lbs of pressure, the earliest failure point stated of the two products with a result in this test |
| 2Rustoleum Leak Seal | not tested | applied to both sides of the bucket but a large gap remained; did not hold water, failed this test | transcript transitions to this brand with 'Now for the Rustoleum' but no explicit pull-test result is narrated immediately after; likely a transcript gap | not tested | the only one of the three products still not leaking as pressure climbed through the stated readings (8, 10, 15, 20, 30, 40 PSI); implied winner of this test | definitely has a lot better bond to the PVC than the other two products | failed at an unspecified pressure (transcript only says 'Rustoleum has failed', no PSI given), but did not fail as early as Flex Seal's 2 lb failure |
| 3Perma-Seal | not tested | initial visual inspection suggested it filled the crack well and would 'most likely hold water', but the actual water test showed the bucket leaking; both statements are preserved since they represent two different points in the test (visual assessment vs actual water test) rather than being corrected to one | started flexing just from pulling on it with not a whole lot of force, described as a lot more rubbery than Flex Seal | not tested | began leaking at 8 lbs of pressure, the earliest explicit failure point of the three products in this test | described as real gummy, sticks reasonably well, likened to an adhesive such as rubber cement | no result stated in the transcript for this brand in this specific test; only Flex Seal and Rustoleum's outcomes were narrated |
How it was tested
- cut bucket repair and water-holding test (48 hour rated cure time, 70 hours actually allowed)
- bucket structural pull/strength test (manual pulling on the repaired bucket sides)
- PVC-over-metal-pipe structural integrity/break test (pipe cut in two, product sprayed on, moved outward from the break point)
- PVC pipe underwater air pressure test (drilled holes, pressure gauge, air pressure increased until rupture)
- scratch/adhesion-to-PVC test (qualitative, no measurement)
- metal air tank underwater air pressure test (drilled/existing holes, pressure increased until failure)
“It definitely seems to be the best allaround.”
Data notes and caveats
Only three brands tested (Flex Seal, Rustoleum Leak Seal, Perma-Seal); no prices are mentioned anywhere in this 2018 video, unlike later Project Farm videos which consistently open each brand's segment with a price. The video ends with per-use-case caveats rather than a single clean ranking: Flex Seal is explicitly called the best all-around pick for most home repairs (verdictQuote), but Rustoleum is explicitly named the better choice for applications needing raw strength over flexibility (PVC and metal air tank testing), and Perma-Seal is explicitly named the better choice for applications needing high flexibility (e.g. roof flashing) despite performing worst on the harder structural/pressure tests. Because an overall winner is explicitly declared ('best allaround') despite these caveats, winner is set to Flex Seal rather than null; the caveats are preserved in each product's notes. Meta chapters correspond to test types (bucket leak/strength, pipe break, PVC pressure, texture/metal pressure) rather than to individual brand segments, so chapterMap is false. Several sub-test results are incomplete in the transcript: the PVC-over-metal pipe break test has no spoken measured outcome for any brand, the metal air tank pressure test has no stated result for Perma-Seal, and the PVC underwater pressure test's PSI countdown (8, 10, 15, 20, 30, 40) is not cleanly attributed to each brand's individual failure point beyond Perma-Seal's explicit 8 lb failure and Rustoleum's implied survival to the highest reading.