Flex Seal, 14 oz, 2-Pack, Green, Stop Leaks Instantly, Waterproof Rubber Spray On Sealant Coating, Perfect for Gutters, Wood, RV, Campers, Roof Repair, Skylights, Windows, and More

Resolved my problem with a leaking fiberglass camper shell. It took two full cans to cover two coats over my 8-ft camper shell.

My roof had a leak in the asphalt shingle and clear sealer won't look like a patch.

I used this product to waterproof the underside of my boat marine carpet. I would’ve given it five stars, but it took too long for it to arrive other than that I recommended.

Used this to repair a cracked resin fountain, so far so good!

This product works very well to stop leaks in out gutters.

First, I will list my scores for Adhesion, Ease of use, and Water Resistance. Then, I will elaborate and give my final conclusions.Adhesion: 2/5Ease of use: 5/5Water resistance: 2/5Overall score: 3/5AdhesionThe initial coat stuck quite well with proper prep. I used denatured alcohol to clean the surface, then 60 grit sandpaper to rough the surface and help with bonding, and then another round of alcohol to clean dust. However, one coat will not give the desired results. Much like paint, areas lacking appropriate coverage are more visible when dry. This is where the adhesion becomes an issue. Proper prep, specially sanding, becomes difficult because this sealant is pliable even when dry. Its not possible to do more than the slightest scuff without the possibility of damaging the first coat. Due to the thick nature of the product, expect a lot of drips. The product is very runny fresh out of the can.Once the product is dry, the issues with adhesion aren't over. The commercials for flex seal (and the quality memes) make you believe the bond is like super glue on steroids. This is hardly the case. If there is any heat or any pressure this sealant will not hold. Heat causes it to soften, losing almost all integrity, and pressure will force water through the porous interior (caused by the aerosol delivery).Overall, the adhesion score is due to the drips on the second coat and beyond, and the lack of integrity at anything other then ideal (meaning low to no pressure and heat).Ease of useApart from drips making an even coat difficult on anything not planar to the ground, this is as easy to use as you think. The most difficult part of the process is prepping. The nozzle is fairly accurate and in my experience didn't clog. If you intend to use this sealant in a tight space, the can may be difficult to manipulate.While the can states its a skin irritant, it's not terrible if you get some on you. The toughest part will be peeling it off. Smell is comparable to paint. Tolerable to use with an n95, though respirator will be your best bet. Smell dissipates in an hour or less with ventilation. I do recommend using nitrile gloves and safety glasses.Overall, very easy to use.Water ReistanceAs mentioned in adhesion, any pressure will cause fluids to seep through the sealant. Depending on pressure, could be a sweat, could be a drip. Due to the viscous yet flowing fluid upon first use, even coats are difficult to achieve, which in turn effects sealing. There are pictures on the can of "recommended uses". One shows patching potentially leaking roof shingles, however, on the rear text on the can specifically states not to be used in roofing scenarios. While advertising a flexible barrier (which was attractive to me because I wanted a sealant that would withstand thermal expansion), the actual mechanic of flexing significantly compromises the seal. Hence, most likely, the warning against using it on roofs, since the can heat up to 160°F during summer.Overall, the score is based on the fact in nominal pressure and temperatures environments this will seal and hold out moisture, but in anything else the seal is questionable at best.The overall score of 3/5, and as the title alludes to, means that this sealant is meant for low stress sealing, specifically in areas that MAY leak (and not WILL leak). While not the best sealant, its easy use makes up for potentia shortcomings in other areas.

Works great even on car roofs!!

While not perfect for every application, Flex Seal actually does what it advertises. After reading a lot of the one star reviews, I can see there are a lot of problems with the way people are spraying the product on as well as issues with what is expected.Here are a few tips to get you the best results you can out of a product like this (there are many and they are all basically the same)1. Choose the right kind of Flex Seal. This may seem obvious but there are several kinds of flex seal and they are all used for different things.I. First, the rubber patch/tape is used for large cracks and or holes where you have full access to the area around it. The tape is very thick and can sometimes be unruly. Lay it flat out, cut it, and then roll it while keeping tension on or slap it on like in the commercial. Do not think you are going to move it around and reposition it. You won't. It's a one shot deal for best results. The tape, size to be at least 3-4 times bigger than the hole you are trying to close up. The tape can handle the most pressure in the product line. You must have enough surface area for the tape to get a good grip around the hole if you plan for it to take any kind of real pressure.II. The roll-on stuff is great for large coverage where you want to get fancy putting on thicker and thinner coats here and there. It applies like a sticky paint. I would say that the paint is the most "accurate" because you will use a roller or a brush to put it on and you can make sharp lines, stuff more material in gaps really easily, and handle uneven surfaces nicely.III. The spray is for quick easy jobs as is the weakest under pressure. It's great for sealing things like sky lights, thin plastic objects, joints on gutters etc. Anything that won't see a lot pressure behind it. It's harder to put on thick, but if you apply it like spray paint you can do amazing things with it. Thin, even coats, in a sweeping motion, over and over again and you can cover just about anything.IV. The flex seal one shot caulking is really just like almost any rubber/silicon caulk. I've only used it once and was not all that impressed so I tend to stay away from this one and use 3M stuff instead.2. Pick the right color for your application. The Clear does NOT stay clear. It has a tendency to turn yellow in the sun. If you don't mind that, or won't expose to sun or much light, then the clear is fine, however, I usually stick to white or black. PRO TIP: You CAN mix the colors of the roll-on to make different levels of gray. I am sure Flex Seal would frown but it works for me. It takes a lot of churning to get it all mixed and not streaky. Your mileage may vary.3. Use for the right jobs. Don't expect this to seal high pressure water or stop a leak in a tire. There are limits to its flexibility too. When you can, seal from the inside AND the outside. Use the tape whenever possible as it works the "best" of the products and is insanely tough.4. A little goes a short way. It doesn't cover as much area as you would think. Always get extra.5. Using a screen door in the commercials wasn't an accident. When covering a large area, stick a screen type material to the area and screw it in place. Then use flex seal to cover the gaps in the screen. Use many coats, go slow and the kind of gimmick you see in the commercial is possible. If you cut a 4 inch by 4 inch hole in something, don't expect flex seal alone to seal it. Use a backing material.6. If you are getting bubbles in the flex seal spray you are putting it on too thick. Relax. Put on thinner coats and apply slower. Give it a few minutes to get tacky, then retry.7. Final PRO TIP: CLEAN THE APPLICATION SURFACE. This one is a no brainer, but over and over again I read about people not doing the prep work. Using de-natured alcohol is best if you can. It leaves no residue and on a clean surface like that it makes Flex Seal stick like you wouldn't believe. This is the most important thing other than choosing the right kind of flex seal to use IMHO.Good luck!P.S. One more thing you can do is use painters tape or the like to cover from over-spray. Really if you treat it like a super thick paint, most of the same principles apply.