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If you believe the commercials, then Flex Seal is a miracle product. It will seal anything and can be used pretty much anywhere. In this article, I’ll be considering a video review of Flex Seal and discussing some more aspects of the product, as well as comparing it to other such products. Yes, Flex Seal is just on in several rubber-based sealants. The question is whether it is the best.
I like watching the CrazyRussianHacker (CRH) (YouTube channel) because he cracks me up and he tests things, even things that seem completely useless to start with, such as “banana gadgets.”
But then he tests things which are supposed to be extraordinarily useful, like Flex Seal. Does this stuff really seal as well as the commercials suggest? CRH duplicates some of the things the guy in the commercial claims are possible. And, you know what, he’s not so crazy. He wore a respirator face-mask. I need to do that more often when I’m working with stuff like spray paint around the house. Here is the video:
What He Tests
He pokes two knife holes in a perfectly good 5-gallon bucket and sprays the holes with Flex Seal. He attempts the waterproof strainer trick, spraying a metal-mesh strainer (colander) with the rubberized sealant. And, he attempts to fix ceramic plant pot that had cracked apart during the cold winter, much like what is demonstrated on the commercials. He also decides to try it on a nail-hole in the sole of his boot. He was able to put two layers on everything, including really thick looking layers on the strainer, with just one can. He has so much left over at the end he decides to just go ahead and paint the entire plant pot black to use up the rest of the can. A 10-ounce can is supposed to cover 8 square feet, while a jumbo 14-ounce can covers up to 12 feet.
He waited for the first layer to dry a bit before spraying on the next. According to the Flex Seal instructions, you are supposed to apply several even cracks until you’ve filled all the cracks and holes. However, in their FAQ, they also recommend that you wait for one coat to completely dry before applying another. On the instructions, they say to apply several coats and then wait 24 to 48 hours before applying another coat. This other coat, I would surmise, is as needed. It cures fully in 48 hours.
I suspect that he could have saved what was left in the can by using the same technique as you would for spray paint. Turn the can upside down and spray until it sprays clean. This cleans out the nozzle so that sealant (or paint) does not dry and clog it up. I do not know if this really works for Flex Seal but since you are supposed to allow at least 24 hours before re-applying, you can probably keep using the same can. If you’re like me, you’ve encountered sealants that become useless if you do not use the entire container at once.
One thing he discovers immediately is that you should not spray too much at once, but rather go for thin layers. Otherwise, much like spray paint, the sealant will drip and run.
CRH only waits about an hour before testing for water-tightness. I guess he doesn’t like reading instructions, because, after all, he’s crazy. He does point out that you may want to let it dry a little longer.
Does Flex Seal Work? Results of Flex Seal Testing
CRH’s boot didn’t work out. Not because the Flex Seal didn’t work, but because he discovered a much worse whole in the side of the boot, in an area on which the seal probably would not have worked. The bucket held water and the strainer became a water-proof container. As far as the ceramic plant pot, well it has a hole in the bottom which is supposed to be there, and the purpose was to basically bind the pot back together, not make it waterproof. This appears to have been successful.
Other Colors Besides Black
For when you want things to not be black, Flex Seal comes in other colors
- Brite (a bright white color)
What Flex Seal Is For
According to these tests, even when not fully cured (I’m assuming) Flex Seal works. But let’s be clear about what it is meant for. This sealant is meant to seal things against water. It is not for gasoline tanks or for containing any other liquid chemical. And, it is absolutely not to be used on anything that comes into contact with drinking water. This means you should not be sealing up your plumbing pipes with it, although you could use it on a PVC waste pipe, It should also be used in well-ventilated areas, which means mostly outdoors. You can use it indoors, but you should make sure that windows are open and there is plenty of ventilation. And wear a mask like CRH does.
Flex Seal is recommended for roof leaks, gutters, sealing skylights, leaky hoses, windowsills, PVC pipes, flashing, duct work, foundations, awnings, vent pipes, chimneys, downspouts, a/c drip pans, RV’s and campers, trailers, and more.
The sealant will not withstand a lot of heat and pressure. For example, it’s not a quick fix for leaky steam pipes, although those do exist.
As to the effect this stuff may have on the environment, well I cannot speak to that, but I would not assume it to be environmentally friendly. On the other hand, if you plan on using gallons of the stuff, you may need to consider calling a contractor!
The biggest problem you will find with flex seal, no matter the color, is that it is messy. You’ll only want to use it in places where appearance doesn’t matter. My neighbor tried a can, and while it worked quite well, it got everywhere. However, most people will opt for the spray can, thinking that is the easiest. If you do want a smoother job in a large application, go for Flex Seal in a Can, meant to be brushed or rolled on. While you may still not be able to get a perfectly neat finish, you will be able to control where the sealant goes, and that makes all the difference.
What is Flex Seal? About Liquid Rubber Products
Before you go thinking that Flex Seal is revolutionary, well, it’s not. These types of liquid rubberized compounds have been around for years. Flex Seal just created a clever and quite effective marketing scheme for theirs. Yes, there are other such products easily purchased such as Rust-Oleum Leak Seal Flexible Rubber Sealant, RubberSeal and many others.
The question, then, is Flex Seal better? Well, it may be. Here is a video pitting Flex Seal against Rust-Oleum Leak Seal and Perma-Seal in a head to head bucket battle and other tests including a metal tank and PVC pipe.
One thing I noticed right away is the messiness and viscosity of the Perma-Seal and the Rust-Oleum product. Both of these sprays were uneven and it would be impossible to get anything resembling a neat job. The Perma-Seal dripped quite a lot. The Flex Seal was by far the easiest to apply and went on more like spray paint than the other products.
As you can see, the Rust-Oleum product completely failed the bucket test and the Perma-Seal bucket developed a pinhole leak near the bottom of the gash cut in the bucket. Flex Seal is the only product of the three that sealed the bucket, even though it went on thinner and much more neatly. The Flex Seal also seems to have provided the best structural integrity. Keep in mind that only one coat of each product was used on the buckets. More coats would have resulted in a stronger seal and better strength.
Rust-Oleum seems to have performed the best on PVC pipe. While Flex Seal had the worst ability to adhere to PVC and handle pressure, none of the products can really handle any kind of high-pressure environment and would be useless to seal high-pressure pipes or tanks. Rust-Oleum would be your best choice for PVC and if you notice the description, it says it works for PVC drains, not a pressurized pipe. The tests in this video were meant to be a bit extreme but if you really needed to seal up a waste pipe in an emergency, several coats of Rust-Oleum Leak Seal is probably your best choice. For typical sealant uses, Flex Seal, for me, is a clear winner. It’s not all about advertising.
Another product that I really like to quickly seal up leaky things is Rescue Tape. The great thing about Rescue Tape is that it is not really sticky. You can remove it later without leaving behind a goopy mess. It’s also great for repairing those headphones your kids are always inexplicably breaking.
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