Is JB Weld Waterproof? (A Comprehensive Guide to Its Water Resistance)

For many years, JB weld has been a popular choice for welders, automotive workers, and even art crafters. It works on any surface you can think of.

But is JB weld waterproof? It is one of the most important factors to know before you work with JB Weld. Whether or not you can work with it underwater.

J-B Weld is non-toxic and absolutely resistant to water, petroleum, gasoline, and just about any automotive chemical once fully cured. However, the regular JB Weld is not fully waterproof, and you should use JB Weld WaterWeld for wet-surface and submerged water or gasoline repairs.

Many factors depend on the fact of whether JB Weld is waterproof or not. Down below, let us see that all.

Why does JB Weld need to be waterproof?

There are many problems that can occur when JB Weld isn’t waterproof. If you need to repair plumbing, fuel tanks, tubs and showers, drains, pools and spas, boats and potable water tanks, or almost any other setup that occurs even underwater, you will need waterproof epoxy.

However, if the JB Weld is not waterproof, it will not hold the adhesive underwater. As previously said, a waterproofing epoxy must be capable of doing all of these things. You should also be able to drill, fill, sand, and paint even when submerged after drying. However, none of this is feasible without waterproofing capabilities.

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Making JB Weld waterproof: methods and materials

To make JB Weld waterproof, you will need to use JB Weld Waterweld solution as regular JB Weld is just water-resistant. JB Weld Waterweld is a two-part epoxy putty stick that can be mixed by hand and cured underwater, making it excellent for various underwater projects. The NSF has validated that this is safe to use with potable water.

WaterWeld takes 25 minutes to set and 1 hour to cure after kneading the two-part mixture together by hand. This is easy to understand since the color will be off-white after curing.

You might ask what materials you should consider for waterproofing. We have the answer for that too. Even though you can consider waterproofing for many materials, we will discuss the most important ones.

• Balcony or terrace

Waterproofing construction materials for balconies and terraces must meet a number of requirements. Temperature fluctuations cause small movement on balconies and patios.

Under the average lifespan of these materials, rigid waterproofing materials would break and require repair or replacement in a short period.

• Underwater gas lines

This is probably the most essential material to waterproof. Underwater gas lines can go miles after miles, sometimes even connecting many countries. If the water somehow enters the line, there can be a colossal explosion distorting the proper carrying of gas.

• Walls

Waterproofing solutions for walls must provide more than simply water protection. Vapor barriers and air barriers must also be included. Otherwise, moisture might become trapped in the masonry and carpentry behind the insulation, causing mold, mildew, and/or fungus to proliferate.

• Roof

Roofing materials are watertight in general, but this isn’t enough. Roofs are subjected to a lot of wear and tear. As a result, more waterproofing materials are required. They are either put over the roof as a protective coating or fitted beneath it as part of the roof structure.

What are the disadvantages of using JB Weld in water?

Are there actually any disadvantages of using JB Weld in water? Yes, there are a few minor disadvantages.

• Longer setting and cure time

When you are repairing something underwater with JB Weld, it takes around 4-6 hours to set on the surface and additionally 15-24 hours to cure completely. Hence, it cannot be used as an instant fix. Also, it would be best if you made sure that water doesn’t come in direct contact with it before it is properly cured.

• Soluble in alcohol

Even though JB Weld can withstand high pressure, it can dissolve in alcohol. However, the procedure can be a long process. But, it would help if you still stay careful about that.

What are some tips to follow when using JB Weld in water to achieve strong bonds?

If you want to use JB Weld in water, these tips will help you make sure that you can have the perfect results.

• Allow full drying time

It is very important that you allow JB Weld to be cured fully before you start using the material you have put the weld on. Do not rush with the drying process as it can have leaks easily without curing fully.

• Prepare the surface

When using JB Weld, it’s also a good idea to sand the surface sufficiently to ensure that the adhesive can adhere to it.

• Remove adhesive from hands promptly

Sometimes while working, the adhesive can be stuck to your hand. If you do not have access to a hand cleaner or the glue is too rigid that even the cleaner isn’t sufficient, try acetone or lacquer thinner. If you get anything on your hands, try to clean them as quickly as possible.

• Speed up the drying time

If you want to dry your JB Weld quickly, then you can try these techniques. However, we do not recommend quick drying it. To dry it quickly, try applying heat. You may also use a piece of window screen to hold the putty in place until it hardens.


One question often pops up when using JB Weld is JB weld waterproof. You need to understand a few things before directly getting this answer. Hence, to get the proper solution and understand the use of JB Weld properly, make sure to read this article, and we hope all your queries will be answered in our detailed discussion above.