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Making from Sheet Metal – which materials are better for outdoor use?

The availability of different sheet metals in various grades and thicknesses is excellent news for the hobbyist, the prototype, and the garage machinist. But sometimes, it can take effort to choose the suitable material for your project. This article will look at using brass, copper, Aluminium, and stainless steel to make furniture and fixtures intended to spend at least part of their lives outdoors and in the elements.

The elephant in the room – corrosion

Nothing you make out of sheet metals for outdoor use can ignore the corrosion question. Iron rusts. Copper goes green and eventually starts to disintegrate in a very similar process. However, there are some effective sheet metal alloys of iron and copper that can do a great job out of doors. Then there is Aluminium. Aluminium doesn’t corrode at all; it just gets less shiny. Most Aluminium alloys corrode worse than pure Aluminium.

  • Stainless steel was explicitly invented because the iron and all of the steels of the time poorly rusted and using them around any water was a maintenance nightmare. Stainless is an amazing alloy of steel which doesn’t corrode at all in the presence of water.
  • Brass is an alloy of copper developed many centuries before stainless steel, but for essentially the same reasons. Copper is great, but copper alloys can be better. Several alloys, called corrosion-resistant brass, can even be used at sea with relatively little maintenance. They can handle a little rain and/or snow.
  • Aluminium is ideal for use outside as it is. Aluminium does oxidize, but unlike copper or iron, the white, powdery Aluminium oxide seals off the pure metal underneath and prevents more than the thinnest surface layer from corroding.

Once you know what levels of corrosion you are willing to tolerate, choosing the suitable metal based on its other characteristics is easy. We have guides for working with these metals in different contexts.

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