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Brazing vs Castaloy (Cast iron repair rod)

Using Alumaloy and Castaloy is almost identical to using the brazing process with bronze or copper.  In my Alumaloy vs brazing article we talked about some of the similarities.  However, Castaloy is the most

Fix cast iron with no welding

Castaloy

similar to brazing due to the use of flux to prevent corrosion and oxidation. This is important when using a product like Castaloy because cast iron is susceptible to both. When doing repair work you want to avoid the possibility of weakening your fix that way.

A quick overview of brazing will give you an idea of how they compare. With brazing the area to be joined needs to be cleaned and properly prepped: clean edges and no debris. Pieces are placed and clamped if needed.

Flux is applied if using, then tacking is done. The tacking will place a bead of molten bronze in strategic locations to prevent the metal from expanding apart due to heat. Once the tacking is complete the metal is heated to a temperature for the bronze to melt and fills the void. As we have said before brazing will produce a good, strong patch.

Cast iron repair rod

Cast iron repair rod

Castaloy works similarly. The main difference is that when complete, the bond will be stronger than brazing because you are joining iron to iron and making it into a complete whole instead of just a joint. Brazing forms a patch but Castaloy creates a newer and stronger bond. The joint to be melded needs to be thoroughly cleaned, (Please see our article on cleaning). Once properly cleaned and the acid, (provided at purchase), is applied you can then add flux if you desire. The role of flux is to dissolve the oxides on the metal surface. This facilitates wetting by molten metal, and acts as an oxygen barrier by coating the hot surface. It thereby, prevents its oxidation. Additionally, it allows solder to flow easily on the working piece rather than forming beads as it would otherwise. When brazing, the metal repair rod is heated to a temperature that is slightly above it’s melting point.  When using Castaloy, we recommend that you heat the metal being repaired and not the rod itself. When you touch the rod to the metal, it will melt on contact. You will first want to set your tacks to prevent expansion. Once your tacks harden, proceed with mending. Heat the receiving metal to temperature and allow the molten Castaloy rod to fill in the gaps. Once the bond has cooled it will be as strong as it once was, if not stronger.

We hope this has helped to clear up any questions you may have had regarding the differences of our product and the brazing process. As always, if you have any questions or suggestions for please address them to our Castaloy forum and we will do our best answer them and make new information available to our customers as requested or needed

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