Once again, my mail bag is empty. Since I have no questions to answer, I will write this month about a product I have used for years, but have been asked a lot of questions about lately. People have joked over the years that if it were not for “JB Weld” my cars would have fallen to the ground in pieces. In fact, there is a ring of truth to this.
“JB Weld” is a two-part epoxy product. It comes in several different flavors, but the concept is the same. There is a “JB Quick” that sets up in about five minutes, but once cured is not as strong as the original JB Weld. For applications im-mersed in water there is a JB Weld that sets up under water, appropriately called “JB Water Weld.”
JB Weld has a cured tensile strength of 3,960 psi. Though it sets up in 4-6 hours but takes 24 hours to cure. Additionally, it is non-conductive (well-insulated) and can be filed, drilled, tapped, and painted. When fully cured, JB Weld is completely resistant to water, gasoline, and about every other petroleum product or automotive chemical. This epoxy will work in tem-peratures up to 500 degrees Fahrenheit, but will fail if heated beyond this point. This epoxy sticks well to all metals. However, it does not stick to flexible rubber, leather, vinyl, canvas or polypropylene plastic.
I first used JB Weld to fix a pot metal door lock assembly in my first Subaru Legacy. Somebody recommended it, and I reluctantly tried it. Much to my surprise, it worked. Since then, I have found countless uses for it over the years. The right side horn on the MG TD I recently restored is largely made out of JB weld. The horn is a cast assembly, and the throat of the horn was smashed, though the mechanical part of the horn still worked. Unfortunately, the throat of this horn is an una-vailable part, so I decided I would try to repair it with the epoxy. Using the horn on the other side as a pattern, I was able to rebuild the throat of the horn with the epoxy. I have glued bolts on to broken-off studs and been able to back the stud out. I have fixed my wife’s stainless steel pots and pans, using it to replace broken rivets, knobs and spot welds. It has held up to both the heat and the dishwasher. I have often used this epoxy in my model-making, using it as both a glue and to make my own cast model parts. I have recently been asking people if they are familiar with this product. A number of people have told me that they use it, and use it often. Surprisingly, a few people have told me they either never heard of it, or have heard of it but never used it before.
Here are some tips for new users:
- As with any type of adhesion, make sure the surface is clean and free of any grease or greasy residue. Clean the surface with soap and water and dry.
- Before applying the epoxy, rough up the surface with sand paper or a wire brush and clean with acetone or lacquer thinner. Make sure you mix exactly 50% resin to 50% hardener. The mixture has to be close to 50-50 or it will not fully cure.
- Allow the epoxy to cure before it is moved. I often use tape to hold the epoxy in place until it hardens. If this is not possible, use the JB Stick putty, as this will hold its shape until it cures.
Hopefully, if your tool box isn’t already well-stocked with JB Weld, it will be soon! It has served me very well over the years, and I’m certain you will find it as indispensable as I have, if you haven’t already enjoyed the benefits of this product.
(This column is a Q & A column with you asking me questions and after researching the answer I will reply. Any questions ‘automotive’ is fare game, I might not know the answer but hopefully I will find someone who does know.)
Please email all inquiries to: Dave
or snail mail
32 Turkey Hill Road
Richmond VT 05477