How to Fix Cast Aluminum

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Things You'll Need

  • File

  • Wire brush

  • Torch

  • Aluminum brazing rod

  • Wet/dry sandpaper

  • Dual action sander

  • Buffing tool

  • Rubbing compound


Sheet metal can be used to create forms around broken-off aluminum parts. The part can then be remade within the form with brazing material. Torches with propane work well for heating aluminum up to 1/4 inch thick. Beyond that thickness, MAPP gas or an oxyacetylene torch should be used. Once cured, the brazing material can be drilled, for example, for fixing or recreating parts with bolt holes, etc., or it can be lacquered or painted.


Using torches and heating metal is potentially dangerous. Always follow proper safety guidelines as outlined in your torches' user manuals and wear the proper safety wear, glasses or helmet and gloves.

Image Credit: Hemera Technologies/ Images

Cast aluminum is used in a wide array of items including cars, boats and motorcycles, pipes and vents, and various housing fixtures such as gutters and roofing materials. Although aluminum is highly resistant to corrosion, it is a soft metal and can easily become punctured or cracked. Fix these flaws in cast aluminum using a torch and an aluminum brazing rod. Aluminum brazing rods are made with aluminum combined with zinc and melt at a much lower temperature than straight aluminum, making it easy to melt the rod and fill in and patch cast aluminum parts.


Step 1

Clean the area to be patched with aluminum cleaning tools, such as a file or a wire brush. Caustic cleaner can be used if necessary.

Step 2

Use a torch to heat the area to be repaired to the melting temperature of the brazing rod. The area needs to be heated to about 735 degrees to melt the brazing rod.

Step 3

Touch the tip of the brazing rod to the heat area and scratch it quickly back and forth across the opening of the crack or hole until the opening is filled. Keep the area heated but never stick the brazing rod directly in the torch flame. No backing is necessary for filling gaps as the brazing material is self-suspending. It is also fairly self-leveling. After the patch is made, allow the object to cool.


Step 4

Sand and polish the area as needed. For most aluminum sanding jobs, it is best start with a coarse, 180-grit sandpaper and gradually work up to a fine, 2000-grit sandpaper. Use a dual-action sander for consistent, even sanding. Use a buffing tool and rubbing compound to polish the aluminum.



Mason Howard

Mason Howard is an artist and writer in Minneapolis. Howard's work has been published in the "Creative Quarterly Journal of Art & Design" and "New American Paintings." He has also written for art exhibition catalogs and publications. Howard's recent writing includes covering popular culture, home improvement, cooking, health and fitness. He received his Master of Fine Arts from the University of Minnesota.