Which Spray Sealant Brand Wins?
In our test 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 quick take
The short version of why each pick lands where it does, built straight from the measured results.
“It definitely seems to be the best allaround.”
The measured results
Every number below is read straight from the test. Products are listed in the order they finished.
Cut bucket leak test
- 1Flex Seal
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
- 2Rustoleum Leak Seal
applied to both sides of the bucket but a large gap remained; did not hold water, failed this test
- 3Perma-Seal
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
Bucket structural pull/strength test
- 1Flex Seal
took quite a bit of force to fail; narrator felt a couple more coats would have prevented tearing entirely
- 2Rustoleum Leak Seal
transcript transitions to this brand with 'Now for the Rustoleum' but no explicit pull-test result is narrated immediately after; likely a transcript gap
- 3Perma-Seal
started flexing just from pulling on it with not a whole lot of force, described as a lot more rubbery than Flex Seal
PVC underwater pressure test
- 1Flex Seal
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
- 2Rustoleum Leak Seal
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
- 3Perma-Seal
began leaking at 8 lbs of pressure, the earliest explicit failure point of the three products in this test
Scratch/adhesion to PVC test
- 1Flex Seal
seemed pretty good visually but did not stick to the PVC very well, easy to scratch off
- 2Rustoleum Leak Seal
definitely has a lot better bond to the PVC than the other two products
- 3Perma-Seal
described as real gummy, sticks reasonably well, likened to an adhesive such as rubber cement
Metal air tank underwater pressure test
- 1Flex Seal
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
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
no result stated in the transcript for this brand in this specific test; only Flex Seal and Rustoleum's outcomes were narrated
All measurements (2 more)+
Cure time required
- 1Flex Seal
needed the longest cure time of the three products; narrator allowed 70 hours instead of the required 48 to be safe
- 2Rustoleum Leak Sealnot tested
- 3Perma-Sealnot tested
PVC-over-metal-pipe structural break test
- 1Flex Seal
included in this test but no spoken comparative outcome/measurement was given in the transcript
- 2Rustoleum Leak Sealnot tested
- 3Perma-Sealnot tested
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.
