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Informational articles on how to fix items made of metals such as Aluminum, Cast Iron and Stainless Steel.

How to guide: Cleaning metals for repair part 1 aluminum repair with Alumaloy

Cleaning before using any of our products is very important.  I plan to do a three part how to guide explaining what is needed to be done for all three of our metal repairing products.  In some cases it may just need to be wiped with a cloth.  However, in most cases, it will require an abrasive or mechanical cleaning. This usually can be accomplished with the use of a wire brush or sandpaper.  Cleaning is very important particularly with How to guide: cleaning metals for repair part 2 cast iron repair with Castaloy and How to guide: cleaning metals for repair part 3 stainless steel repair with Steelaloy because it reduces the chances of future corrosion and helps make a more solid melding.  In this article I would like to talk about Alumaloy, a product used to repair aluminum.  More information can be found here about the physical properties of Alumaloy.

Aluminum is generally one of the easiest metals to work with as it is the easiest to clean. However,  be careful to take all of the precautionary measures to ensure a great outcome.  Areas to be mended will need to be completely free of paint, dirt, oil and other debris before using our aluminum repair rod. Any contamination can cause poor wetting and will eventually weaken the join points.  A smooth break may only need a quick wipe with a clean cloth or rag.  Be sure any liquid is removed in this step.   A small wire brush or sandpaper will usually be enough to remove particles and matter from a rough piece. If your project requires a more aggressive cleaning, you may want to use a wire wheel on a drill. Make sure to wipe it down afterward to remove any loose grit or debris. Also, you will want to keep in mind that it is important to maintain the proper surface roughness as wetting on a rough surface occurs much more readily than on a smooth surface of the same geometry. If there is any oil on the metal, you may need to use a cleanser to remove it.  Be sure the area is completely dry after use or thoroughly wiped down to avoid fumes and fire hazards. Be thorough so that when you begin the repair process, you do not have to stop once the metal has been heated and you have begun your repair.

Part 1:  How to guide, cleaning focuses on Alumaloy to repair aluminum.
Part 2:  How to guide, cleaning focuses on Castaloy  to repair cast iron.
Part 3:  How to guide, cleaning focuses on Steelaloy to repair stainless steel.

We hope these cleaning guidelines have been helpful to you in the use of our products. If you have questions or comments please feel free to visit our aluminum repair forum or post your comments directory to this article.  Feedback always helps us to serve our customers better.

Physicial properties of Alumaloy: Aluminum repair rod

We have received a number of questions about the strength and durability of Alumaloy on our aluminum repair forum.  We understand that people have concerns and we would like to address them.  In an effort to do this we are going to provide some of the metallurgical specs of Alumaloy here as well as an explanation of what they mean to you.  You will note we might compare the properties of Alumaloy with the properties of aluminum.  We take pride in our product and stand behind it 100%.  It is our hope that this information will reinforce your confidence in our product and us.

Tensile strength: 39,000 PSI
That means 39,000 pounds per square inch is required to tear it apart the meld of two pieces joined with Alumaloy.

Compression strength: 60,000 to 75,000 PSI
A meld with Alumaloy can withstand between 60,000 and 75,000 pounds per square inch of crushing power before breaking apart.

Ductility: Good
When Alumaloy is melded to other aluminum it becomes just as easy to shape as the rest of the material it is bonded with.

Electrical conductivity: Good
Alumaloy has a relative electrical conductivity to aluminum so shouldn’t impede any electrical repairs it is put to.

Thermal Conductivity: Excellent
Heat transfer for Alumaloy is consistent with aluminum and will maintain thermal qualities present before the repair.

Corrosion penetration: Excellent
Aluminum is resistant to corrosion and Alumaloy shares that property. Melds made with it will not corrode over time unless the aluminum itself does.

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


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

What is Flux? How is flux used to repair cast iron and steel?

What is Flux?

Flux is a chemical cleaning agent that facilitates soldering, brazing, and welding.  It does this  by removing oxidation from the metals to be joined.  In high-temperature metal joining processes, the primary purpose of flux is to prevent oxidation of the base and filler materials. It also helps transfer the heat evenly over the metal surface.  The use of flux also allows solder to flow easily on the working piece rather than forming beads as it would otherwise thus making the hot metal much easier to work with.

In summary, flux has 3 main components;

1. Chemically- it cleans metal surfaces to assist the flow of filler metals over base metals and provides a protective barrier against re-oxidation and heat scale.

2. Thermally- it assists with heat transfer from heat source to metal surface

3. Physically- it helps in the removal of surface metal oxides.

We strongly recommend the use of flux with your Castaloy and Steelaloy projects.

What is brazing? How to guide: brazing to fix aluminum, cast iron and steel

Brazing is a metal joining process where a metal filler is heated and distributed evenly between two or more close fitting parts. The filler metal, usually bronze or copper, is heated to slightly above it’s melting point. It is then allowed to flow over the base metal and cooled to join the pieces together. This is known as “wetting”. Usually a flux is placed on the metal. Flux is required to prevent oxides from forming while the metal is heated. The flux also serves the purpose of cleaning of any contamination left on the brazing surfaces. The brazing process is a similar process to soldering, except the temperatures used to melt the filler metal is above 800 degrees F. Torch brazing is the type of brazing that is used with Castaloy, Steelaloy, and Alumaloy. This is the most common form of brazing and works best when working with a small repair.

The two most important factors in obtaining a solid repair are surface preparation and temperature control. There are two main methods for cleaning parts prior to brazing.  One is to use an abrasive method to scuff up the surface area and the second is chemical cleaning. When using mechanical cleaning it is important to maintain the proper surface roughness as wetting on a rough surface occurs much more readily than on a smooth surface. The next area of concern is the effect of temperature and time on the quality of brazed joints. As the temperature of the braze alloy is increased, the alloying and wetting action of the filler metal increases as well. In general, the brazing temperature selected must be above the melting point of the filler metal. In general, the lowest possible braze temperature is used in order to minimize brazing time and the associated costs.

Brazing VS Alumaloy (Aluminum repair rod)

I would like to address and discuss a specific question presented by a customer on our Alumaloy forum recently.  “What is the difference between brazing and using Alumaloy on my aluminum repair project?”  Please allow me a few moments to lay out the similarities and differences of repairing your aluminum project with Alumaloy versus repairing by brazing with bronze or copper.

Fix aluminum with no welding


First I will cover the similarities. Most metal workers will recognize that working with Alumaloy is very similar to brazing with bronze or even copper in the respect that you are bonding a broken piece of metal by melting another piece of metal to form a bond at the break. The process of brazing is a bonding of two or more metal parts with a different type of metal. Most often bronze is the metal of choice, although copper may also be used. When using Alumaloy you are also bonding two pieces of metal together. However, now you are using an aluminum alloy. In both cases, the metal is heated and melted to repair the break. The tools that are used are the same and the temperature that you need to work at is also the same. Another similarity is the use of a product called “flux”. (Flux protects the metal from oxidation during the bonding process, reducing the chance of oxidation.)  Flux is used with some of our other products such as Castaloy and Steelaloy but not Alumaloy.

In both brazing and in working with Alumaloy, the step by step process of repairing aluminum is identical. The parts to be joined are lined up and the tacking is done. To “Tack”, means that the metal to be joined with the bronze or Alumaloy is heated and the rod is applied to the meeting place. The rod will have a lower melting point than the parts to be joined so it will leave a droplet joining the two. Other “tacks” are done, using the same process, to keep the metal parts from pulling apart due to expansion from the heat. Once the tacking is done the main repair can begin. Again the metal parts are heated up to the temperature for melting and the rod is touched to them leaving behind liquid metal to fill in the gap and hold the two parts together. If done properly, all the gaps will be filled with rivulets of now hardened metal, holding the two independent parts as one whole, making the repair complete.

Aluminum repair rod

Aluminum repair rod

Now I will discuss the differences. Really, there is only one difference, Alumaloy is stronger. It is stronger than aluminum, copper and bronze. This is due to the fact that it is an alloy. In our special formula, we have been able to combine aluminum with other metals to create a product that has more tensile strength than in its original form. By using an alloy that has the same properties as the metal that was broken, a more complete bond is created. Simply put, your aluminum is now better than when you started. Since the area that was broken before may have been due to a shortcoming in the original metal, you can now rest assured that you have added a new level of durability to your project.

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 please address them at our aluminum repair forum and we will do our best to answer them and make new information available to our customers as requested or needed.

How to guide to repairing aluminum products

How easy is it to repair aluminum products with Alumaloy?



It really is easy to do repairs with Alumaloy. You can do it with just a few tools and it isn’t complicated. Once you have done it a few times there will be little reason to throw things out that seem hopeless.

Tools you may need:


  • Aluminum Repair Rod(s)  “Alumaloy rod(s)
  • Wire brush for cleaning aluminum
  • Sand paper for cleaning aluminum
  • Pliers to hold Alumaloy rod
  • Propane torch to heat aluminum
  • Gloves to protect your hands
  • Safety glasses or face shield to protect your eyes and face
  • Stable work surface or vice to support the aluminum product needing repair
  • Rags for cleaning
  • Draft free work area

How to repair aluminum products with Alumaloy:


  1. Be sure to use appropriate safety gear to protect eyes and hands.
  2. First identify the break. Then situate the aluminum product in a stable position on a flat surface or with a vice. This will keep it from moving while you work and keep you safe. This area should be open but draft free.
  3. Once the aluminum in need of repair is secure, clean the break of debris. This may just mean a wipe with a rag up to a vigorous brushing with a metal brush or sand paper. DO NOT USE DEGREASERS OR CLEANERS THAT MAY BE FLAMABLE!
  4. Now that the aluminum break is clean and ready, you will use your torch to heat the aluminum. Do not heat the Alumaloy rod. You want the heat of the broken aluminum to melt the Alumaloy. Keep the heat in motion over the area you are working with. Test the surface for temperature by pulling the torch away and touching with the Alumaloy rod to it. When the Alumaloy melts and starts to flow freely you are at the optimal working temperature. You will need to reheat that location from time to time to keep the Alumaloy flowing. Work the Alumaloy into the broken area, letting it fill in the hole or crack, switching from heat to Alumaloy.
  5. Once the break is covered thoroughly, allow to air cool. After the aluminum product is cool you may need to sand or grind it to smooth the surface or reshape it. This step all depends on the use or needs of the repaired aluminum product.

It is just that simple. Alumaloy was designed so anyone can use it to make repairs on everyday products. You don’t have to have special skills or be a welder to use it. Common sense, patients, Alumaloy and a few tools will see you repairing all sorts of aluminum products. Never again will you have to throw something out because you do have the skills to restore them.

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