Why JB water weld not hardening?

• Post By: Brandon M. Fox  • Updated: 03/13/21
• JB weld

If you have repaired at least some of your household plumbing systems, then you have already heard of JB water weld, right? Well, this is one of the renowned solutions out there.

JB water weld is an epoxy putty that can fix almost anything from household to industrial projects. It is a quick and easy one-stop permanent system.

But the most common problem users run into is JB water weld not hardening. Well, there can be quite a few reasons behind it. We will discuss this in a minute. 

But first, let’s know what JB water weld is? And how you can make the best out of it. So, let’s dive deep. (Learn more about How to remove JB weld?)

What is JB water welding?

JB water welding is an underwater quick fix system. It is a two-part putty system. All you need to do is knead the required amount of putty and place it on the desired surface. 

It will seal any leak or cracks for you in an hour or so. You can also use this for regular projects and household items. 

This super-strong epoxy putty can repair any item including metals such as aluminum, copper brass, iron, etc. It can also work on PV plastic, steel, fiberglass. 

So, you can use it for a wide range of projects. It is great for any plumbing work like on tub, showers, or drains. It can also be your savior while repairing fuel tanks, marine and boat parts, and water tanks.

And the cool thing is the price and size are also reasonable. 

Application of JB water welding

You can use this JB water welding for-

  • Automotive.
  • Underwater projects.
  • Ceramic.
  • Fiberglass.
  • Plastic.
  • Metal.
  • Craft projects.
  • Household items.

Why is my JB water weld not getting hard?

JB water weld is a two-part epoxy putty. There can be more than one reason for which your JB water weld is not getting hard. But the most common one is the wrong storage and insufficient kneading. 

First, you need to knead the putty enough to activate it. Cut the required amount of putty. 

You will see there are two parts of the putty in two different colors. Knead them well until they become one uniform color. 

Another thing to look for is how you store the remaining putty after use. Make sure to store the putty in an air-tight container. If you are using the tube it came with, then seal the cap properly.

Get these two basic things right and your JB weld should harden properly.

How long does it take JB Weld to harden?

JB water weld has a set of time. And it is 15-25 minutes. But you have to wait at least 1 hour till the putty fully cures. 

How to tell if the putty is fully cured? Well, it will turn into off white color after the final stage. 

Will JB water weld melt with heat?

JB water weld is an epoxy putty. It can stand up to 300 degrees Fahrenheit. 

So, you can fairly say it will melt under extreme heat. Therefore, think twitch before using it on a surface that gets hotter than 300 degrees Fahrenheit.

How strong is JB water weld?

JB water weld has a tensile strength of 1300 PSI. After being finally cured, you can drill, sand, file, or even paint it.

Can JB water weld work underwater?

Well, as the name suggests, JB water weld is specially made for underwater application. It is specifically engineered for permanent repair underwater or moist area.

You can safely say that the JB water weld is water-resistant. 

Is JB water weld toxic?

JB water is drinking water safe. So, you can comfortably use it for household plumbing and other water sources.

Which chemical substances can JB water weld resist?

JB water weld can resist most chemicals. It can also resist gas or oil. So, you can use it for a wide range of household and industrial projects.


JB water weld is your one-stop plumbing solution. You can easily and quickly fix any water source and underwater items with it.

If you are still worrying about your JB water weld not hardening properly, then just knead the putty properly. You have to knead until you see a uniform color. 

That’s how easy it is to use JB water weld. Just cut the putty, knead and apply. There you have it, a quick and easy solution to every plumbing and other household problem.

Related post

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  5. How Long Does Jb Weld Take To Dry?
  6. Jb Weld Cure Time vs Temperature
  7. Will JB Weld Work On Plastic?
  8. Flex Seal Vs JB Weld

Brandon M. Fox

I have completed Diploma at Welding. I have spent 10+ years in Welding. Now love to write about welding and welding products and share my own experiences. Find me: Twitter | Facebook
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