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Home Improvement

Best Sealant

Time makes fools of us all and rots all of our belongings. From the boat to the home, sealants keep our engines running, houses standing and electronics humming by simply blocking out the elements. There are numerous kinds of sealants and each of them does a specific job, which means you need to be diligent to avoid using the wrong one and potentially ruining something expensive.

Below you will find lists of the best sealants in each of the major categories chosen for their cost efficiency, working life and tightness of seal among other qualities. Do the research, buy the best and seal the deal.

Blue Magic 8024 ThermoSteel High-Temp Metal Repair

ThermoSteel, from Blue Magic is the highest temperature sealant on the market. This sealant is designed to withstand temperatures up to 2400oF, far beyond what some other high temperature sealants can withstand. This makes ThermoSteel ideal for repairing difficult repairs, such as those to barbecue grilles, exhaust manifolds and furnaces. The compound withstands contact with direct flame, which not all high temperature sealants can do. It is a thick compound, which allows it to fill cracks, holes and pits. ThermoSteel comes in three ounce packages for home use, as well as a 25 ounce professional size.

Permatex Ultra Copper Maximum Temperature RTV Silicone Gasket Maker

Permatex is probably the best-known name in automotive sealants, producing an extensive line as well as number of other products for the automotive and auto repair industries. This copper sealant is part of their "Ultra" line, designed for use in extreme situations. The sealant has copper chips in it, which allow it to withstand temperatures up to 700oF. Even if something were to happen to the silicone in the sealant, the copper alone would hold, continuing to seal. As copper was commonly used for high temp gaskets before high temperature sealants were invented, you can be sure that it will withstand the temperature and keep on working.

Deacon Crow-Seal #4402 High Temp Sealant

Deacon Crow-Seal #4402 High Temp Sealant

Deacon produces a line of high temperature sealants, mostly for use in industry. Crow-seal #4022 is their highest temperature product, able to withstand temperatures up to 2000oF. The product is available in either caulking tube or can with a screw-on lid. The sealant is smooth and tacky and will readily stick to any clean, oil-free metal surface. This sealant air-dries within an hour, but then requires a heat cure at 500 degrees to be fully set. While it is recommended for any metal-to-metal sealing need, it is not recommended for use where there is water or steam present.

Permatex 81160 High-Temp Red RTV Silicone Gasket

Like the Ultra Copper sealant and gasket maker, this product also comes from Permatex. This one is not from their Ultra line, so doesn't meet as high a temperature as the Ultra Copper does. However, it is still good up to 600oF and 650oF intermittently. It can also resist intermittent contact with automotive and auto shop fluids, without damage. If you don't need the extreme temperature capability of the Ultra Copper, this is a great alternative. The red-colored sealant is thick and can be used to make gaskets as well, eliminating the need for gaskets or for cases where there is no gasket available. Today's tight tolerance engines don't always use gaskets, depending at times on products such as this one.

Sil-Bond RTV 6500 Food Grade Silicone Sealant Adhesive Red Hi-Temp 2.8oz

Sil-Bond RTV 6500 Food Grade Silicone Sealant Adhesive Red Hi-Temp 2.8oz

The Sil-Bond line is one that is little known outside industrial uses but they produce a variety of specialty sealants, such as this one intended for high temperature use. A silicone sealant, it has high adhesion for use on all metal, glass, tile and ceramic surfaces. It is highly resistant to the effects of weather and is waterproof. This sealant is able to withstand constant temperatures up to 500oF and intermittent temperatures up to 650oF. It skins over in 10 minutes, tacks over in 17 minutes and cures at a rate of 1/8" of thickness per 24 hours. Once cured, the finished seal is highly flexible, as the sealant can stretch an incredible 500 percent of its cured length.

Permatex 82180 Ultra Black Maximum Oil Resistance RTV Silicone Gasket Maker

If you need a sealant for engines, especially one in which the sealant is going to come into contact with oil, this one's for you. Drawn from Permatex's extensive line of automotive sealants, this is one of their "ultra" line, a series of sealants designed for extreme applications. This sealant has the highest resistance to oil and other automotive chemicals you can find. In addition, it's fast drying, so you can get your engine back together quickly. Retains high flexibility, even at high temperatures. While this isn't a high temperature sealant, it can withstand temperatures up to 500 degrees.

Sika Corporation 106711 Self Lev Sealant

Sikaflex, from the Sika corporation, is a combination polyurethane and silicone sealant, making it one of the few paintable silicone sealants around. This sealant provides superior adhesion on almost all surfaces, even without a primer. The cured sealant retains flexibility and is waterproof, but it is not designed to withstand engine oil. This is the primary sealant we used on the bus bodies, to take care of opening where water might enter. Once dried, it paints well and will not come off. That makes it perfect for auto body applications, even though it was actually designed for construction.

3M 08008 Black Super Weatherstrip Adhesive

When working on the weather-stripping around doors, windows and trunk lids, a different sort of sealant is needed. This product from 3M meets the need exactly, bonding well to both automotive body materials and the rubber weather-stripping. This selection also holds paper, cork and rubber gaskets in place for use in the engine. The sealant withstands vibration and extreme temperature variations, while being good at resisting both oil and water. Black in color, you can't even see it when you use it for installing weather-stripping.

DAP Auto/Marine 100% RTV Silicone Sealant

Billed as both an automotive and a marine sealant, this silicone product from Dap is highly waterproof and weatherproof. It stays flexible, even when cured, despite exposure to extreme weather. Won't shrink or crack, even under direct sunlight. This product is great for resisting vibration, expansion and contraction. A 100 percent silicone product, this clear sealant will last for years.

Amazing Goop Automotive Contact Adhesive and Sealant

A little different than the other products we've looked at, this sealant from Eclectic Products is designed specifically for automotive repairs. It will stick to a wide variety of materials commonly used in automotive applications. You can use it to repair upholstery, headliners, vinyl tops, carpeting and a host of other automotive parts. The dried sealer is paintable and offers excellent chemical resistance and is also water resistant. Comes clear in color.

Sika Corporation 106711 Self Lev Sealant

Sikaflex, from the Sika corporation, is a combination polyurethane and silicone sealant, making it one of the few paintable silicone sealants around. This sealant provides superior adhesion on almost all surfaces, even without a primer. The cured sealant retains flexibility and is waterproof, but it is not designed to withstand engine oil. This is the primary sealant we used on the bus bodies, to take care of opening where water might enter. Once dried, it paints well and will not come off. That makes it perfect for auto body applications, even though it was actually designed for construction.

Loctite 1936537 2 in 1 Sealent

I have a long history of using Loctite's products, which I consider to be excellent. This particular sealant is from a new line of theirs, which is designed to be both sealant and adhesive. That means that it has extremely good adhesion, as well as the necessary characteristics for sealing off whatever it's stuck to. As a home sealant, this is probably about as universal as they come, being perfect for use as weather sealing around doors and windows, as well as waterproofing around tubs, toilets and sinks; in fact, there is little this sealant won't stick to. While waterproof, it's not recommended for applications where the sealant has to remain underwater, such as under the waterline on boats or for an adhesive for under show doors. While an adhesive, it's not designed for load-bearing applications and avoid using in high traffic areas. This sealant is available in a variety of common architectural colors.

Permatex 80050 Clear RTV Silicone Adhesive Sealant

This is a pure silicone sealant which also functions as an adhesive. It's clear in color, although the same product is available in black. This sealant is designed for automotive and marine usages, but not for use on actual engines. Rather, this adhesive sealant is primarily used for repairs in the interior and the bodywork of the vehicle. It bonds well to glass, metal, plastics, fabric, vinyl, rubber weather stripping and vinyl tops. This sealant can be used for repairing the insulation for electrical wiring, providing excellent insulation. The cured sealant is both waterproof and highly flexible, able to withstand temperatures up to 400 degrees.

Red Devil 0816 100% Silicone Sealant

Red Devil is another manufacturer which provides a clear silicone sealant, but they package theirs in a caulking tube, making it more convenient for larger projects than the Permatex silicone sealant. This sealant forms a water tight seal on aluminum, ceramic tile, glass, porcelain, fiberglass, vinyl and plastic. That makes it ideal for many automotive body and interior uses, as well as architectural door frames, windows, skylights, aluminum siding, trim, gutters, pipes and air conditioners. Keep in mind it's not paintable, so be careful where you use it. Cured sealant maintains maximum flexibility and adhesion and will not crack, shrink or peel. It has a 50 year limited manufacturer's warranty.

Permatex 82099 Spray Sealant

This product from Permatex is rather unique, in that it's sprayable, rather than being a gel that needs to be squeezed out of a tube. That makes it ideal for applications where an area needs to be quickly covered such as with temporary emergency repairs. Use it for low pressure leaks in hoses, oil pans, differentials and transmission pans. It works for both metal and plastic parts, so it will also seal radiator and windshield washer reservoirs alike. Additional coats can be added for thicker coverage and greater strength and this product resists common automotive and auto shop chemicals.

Star brite Silicone Adhesive Marine Sealant

Star Brite is a specialty manufacturer of marine chemicals and products. As such, it's no surprise that they would have an excellent silicone sealant for marine applications. This sealant sticks to a variety of surfaces commonly encountered in marine applications, such as fiberglass, wood metal, glass and even some plastics. It is ideal for putting on deck hardware, providing a waterproof, airtight bond, and when it's time to remove or relocate the fitting, the sealant comes off cleanly and easily. This product can be used both above and below the waterline, meaning you only need one sealant for all your marine needs. Available in a number of colors, it is not affected by sunlight, weathering, most chemicals and solvents. It dries tack-free in less than an hour and cures completely in 24 hours.

3M Marine Adhesive/Sealant 5200

3M is known for providing excellent quality coatings and adhesives, amongst their extensive line of products. This marine sealant, part of their Industrial Adhesives and Tapes division doesn't disappoint. This is a very high strength adhesive which can be used above and below the waterline as it provides a watertight bond which isn't affected by weathering or exposure to salt water. Highly flexible, the sealant remains bonded to all common marine substrates, even through the stress of pounding seas and constant flexion. It absorbs and dissipates shock extremely well while maintaining a strong bond. Ideal for any heavy-duty applications where the sealant will take a beating, this marine sealant comes in gallons, tubes, or cartridges for caulking guns.

DAP Auto/Marine 100% RTV Silicone Sealant

Billed as both an automotive and a marine sealant, this silicone product from Dap is highly waterproof and weatherproof. It stays flexible, even when cured, despite exposure to extreme weather. Won't shrink or crack, even under direct sunlight. This product is great for resisting vibration, expansion and contraction. A 100 percent silicone product, this clear sealant will last for years.

Eclectic Amazing Goop Marine

Amazing Goop, a trademark name of Eclectic, has an excellent series of high strength sealants. This marine sealant which is apart of this series is specially formulated to be UV resistant. This makes it perfect for any outdoor application (not just marine environments), where the sealant will be constantly exposed to sunlight water or extreme temperature. It also bonds very well to vinyl, rubber, metal, glass and wood. Unlike some of the other sealants we are looking at, this one can be safely painted when cured. Resistant to abrasion and very flexible, this marine sealant is great for bonding items subject to extreme vibration.

Travaco Gluvit Epoxy Waterproof Sealer

This is a slightly different product than the others we've looked at. Rather than a one-part sealant which air dries, this is a two-part epoxy product which cures by chemical reaction. That makes it possible to use it in places where it may not receive adequate air to dry normally. It's ideal for providing a barrier coat on hulls and decks, regardless of whether they are fiberglass, wood, aluminum or steel; this product will protect them all. It excels in its primary purpose for repairing leaks, filling hairline cracks, and restoring structural integrity. When cured, this marine sealant provides a hard, yet flexible seal, which will move with the motion of the boat while maintaining structural strength. While it can be used as a stand-alone product, for maximum UV resistance this sealant should be painted after application.

Permatex 82180 Ultra Black Maximum Oil Resistance RTV Silicone Gasket Maker

If you need a sealant for engines, especially one in which the sealant is going to come into contact with oil, this one's for you. Drawn from Permatex's extensive line of automotive sealants, this is one of their "ultra" line, a series of sealants designed for extreme applications. This sealant has the highest resistance to oil and other automotive chemicals you can find. In addition, it's fast drying, so you can get your engine back together quickly. Retains high flexibility, even at high temperatures. While this isn't a high temperature sealant, it can withstand temperatures up to 500 degrees.

Permatex Ultra Copper Maximum Temperature RTV Silicone Gasket Maker

Permatex is probably the best-known name in automotive sealants, producing an extensive line as well as number of other products for the automotive and auto repair industries. This copper sealant is part of their "Ultra" line, designed for use in extreme situations. The sealant has copper chips in it, which allow it to withstand temperatures up to 700oF. Even if something were to happen to the silicone in the sealant, the copper alone would hold, continuing to seal. As copper was commonly used for high temp gaskets before high temperature sealants were invented, you can be sure that it will withstand the temperature and keep on working.

Sika Corporation 106711 Self Lev Sealant

Sikaflex, from the Sika corporation, is a combination polyurethane and silicone sealant, making it one of the few paintable silicone sealants around. This sealant provides superior adhesion on almost all surfaces, even without a primer. The cured sealant retains flexibility and is waterproof, but it is not designed to withstand engine oil. This is the primary sealant we used on the bus bodies, to take care of opening where water might enter. Once dried, it paints well and will not come off. That makes it perfect for auto body applications, even though it was actually designed for construction.

Star brite Silicone Adhesive Marine Sealant

Star Brite is a specialty manufacturer of marine chemicals and products. As such, it's no surprise that they would have an excellent silicone sealant for marine applications. This sealant sticks to a variety of surfaces commonly encountered in marine applications, such as fiberglass, wood metal, glass and even some plastics. It is ideal for putting on deck hardware, providing a waterproof, airtight bond, and when it's time to remove or relocate the fitting, the sealant comes off cleanly and easily. This product can be used both above and below the waterline, meaning you only need one sealant for all your marine needs. Available in a number of colors, it is not affected by sunlight, weathering, most chemicals and solvents. It dries tack-free in less than an hour and cures completely in 24 hours.

3M Marine Adhesive/Sealant 5200

3M is known for providing excellent quality coatings and adhesives, amongst their extensive line of products. This marine sealant, part of their Industrial Adhesives and Tapes division doesn't disappoint. This is a very high strength adhesive which can be used above and below the waterline as it provides a watertight bond which isn't affected by weathering or exposure to salt water. Highly flexible, the sealant remains bonded to all common marine substrates, even through the stress of pounding seas and constant flexion. It absorbs and dissipates shock extremely well while maintaining a strong bond. Ideal for any heavy-duty applications where the sealant will take a beating, this marine sealant comes in gallons, tubes, or cartridges for caulking guns.

Great Stuff Pro Gaps & Cracks 24oz Gun Foam

Dow Corning provides a canned foam sealant in two different grades; a consumer grade and a commercial "pro" grade. This is the pro grade, although the same sealant comes in a disposable can. Specifically formulated as a gap filer, this foam sealant is idea for places where walls don't meet, cracks that have formed in masonry or around windows and doors, where there is no insulation. As a crack sealer, this one doesn't expand as much as some of the other versions. The pro version doesn't come with a nozzle, but rather is designed to work with a separate gun that has an integral nozzle. This saves on sealant, as unfinished cans can be removed and resealed for later use. While the cost of the gun makes the overall cost higher, if you use a foam sealant regularly or even occasionally, the savings on materials makes it worthwhile. You'll also find that it's easier to control the sealant by using the gun. There are also specialized versions of this product available for pest blocking, sealing doors & windows and for sealing walls & floors.

The gun has a stainless steel barrel for longer life and is cleanable after every use. It also eliminates the common problem of post-dispensing drip, one of the biggest nuisances of working with any sealant. You'll save money on both the gun and the cost of material, as you won't have to throw away partially used cans. The can adapter, needle and check valve are all made with a non-stick coating, to make it easier to clean the gun. A flow control allows you to apply a bead from 1/8 up to 3 inches in width.

GREAT STUFF Big Gap Filler Insulating Foam Sealant

The same gap filler that I selected for the number one slot comes in a consumer packaged can as well. This allows you to use it for smaller projects, without having to spend the money buying the gun. They also have a "Big Gap Filler" version, which is designed for filling gaps up to three inches wide. This comes in 12, 16, and 20 ounce cans. One 20 ounce can fills as much space as you could fill with 30 standard tubes of caulking. The expanding foam in Great Stuff Big Gap Filler dries tack free in 10 to 15 minutes and can be trimmed in 60 minutes. Although hard, it is flexible as well, so that it can move along with any shifting in the structure. It is paintable, stainable and sandable, for a seamless exterior on any structure it is used on. This product provides excellent adhesion to many common architectural substrates, making it ideal as either a gap filler or for insulating small areas.

Owens-Corning 627720 Insulating Foam Sealant for Gaps and Cracks

Owens-Corning is probably the biggest supplier or insulation in the company, with their well-recognized Pink Panther logo and distinctive pink color. This is their consumer version of a polyurethane foam sealant, specifically formulated for sealing gaps and cracks. The can's nozzle is designed for producing a bead up to 1 inch in width, but can be layered to allow up to three inches, without any problem. The cured product has no shrinkage and provides a weatherproof seal that helps keep heat and cold out of your home. This product is also available in a pro version, which uses a gun rather than a nozzle, much like the Dow product listed as number one.

Touch 'n Foam 4001031212 MaxFill Maximum Expanding Sealant

Touch 'n Foam has formulated this foam sealant for maximum possible expansion, allowing a single pass with a disposable can to produce a 3 inch wide bead of sealant. That's great for cases where you have large gaps to fill or for corners in framing, places where the roof meets the walls and any other place where it might be difficult to insert standard insulation. Use it for plumbing pipes piercing an outer wall or other places where there are gaps in the original construction. This product fills those spots, stopping drafts and ensuring that your home is weatherproof. It is also great for keeping insects out, as they can't easily eat their way through the foam. The fully cured product is sandable and paintable, as well as having Class A fire resistance.

CRC Minimal Expansion Foam Sealant

This product is essentially the opposite of the Touch 'n Foam product. Whereas it is designed for maximum expansion, this one provides little expansion. The focus of this product's formulation is providing a permanent waterproof and airtight bond to most surfaces. While usable with architectural surfaces, this is the only foam sealant I've seen that was actually designed for automotive sue as well. The manufacturer, CRC Industries, produces products for automotive, heavy machinery and marine applications, not for homebuilding. Like products designed for architectural applications, this one seals in cracks and crevices, providing an airtight and weatherproof seal. Denser than higher expansion products, it is ideal for sealing trunk spaces and gaps that form between the floor pan and frame of a vehicle.

Rich the Tool Man

Before embarking on the current stage of my life, I spent 15 years as a Manufacturing Engineer in both the medical equipment field (medical electronics) and automotive engineering (city transit buses). After that, I owned a small construction company, mostly doing residential remodeling and commercial tenant finishes. I am no longer in either of these fields, but still get my hands plenty dirty as a consummate do-it-yourselfer; working on everything from remodeling my own home to rebuilding my car’s engines. My hobby (when I can find the time) is woodworking; making everything from toilet paper holders, to shelves, to music stands for my own home. My wife long ago gave up the idea that a two car garage is for parking two cars; it is my workshop.

While I cannot claim to having worked professionally with all types of tools, I have worked professionally with some. This comes from my previous careers, where I had to specify, buy and at times live with those decisions. Additionally, I would have to say that my engineering background has given me a thorough understanding of the construction of such tools. So, while I may not have used a particular type of tool personally, I have the knowledge to cut through all the advertising hype and statistics; in order to get at the truth of how well a tool will operate and last.

In my current career as a writer, I've written over 90 books. This includes my own titles and those I've written on contract. I've also written a complete website on how to build your own home.

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