Sometimes, corrosion isn’t a boogeyman to be avoided. Sometimes you want your sheet metal creations to have that ‘lived in’, ‘antique’ or ‘shabby chic’ look. So, let’s look at a few tips for artfully weathering Stainless steel, copper, brass, and Aluminium sheet metal.
Copper
Copper is known for the bright green colour of its corrosion, called ‘verdigris’. This is the copper reacting with oxygen from the air. This patina is beautiful, but it can take years to develop naturally.
If you want to achieve the same effect quickly, start cleaning and polishing the surface. Mix one-part white vinegar, ¾ parts ammonia and ¼ part non-iodized salt, and mix thoroughly. Wet the copper surface with the mixture using a paintbrush, and if possible, seal it up in plastic for at least an hour. Reapply the mixture, and seal it up again overnight. Reapply daily until you get the desired effect, then clean the remaining mixture with window cleaner and a clean cloth.
Brass
Brass is even easier to age, as you don’t need the ammonia. Mix vinegar and ordinary table salt (keep the 4:1 ratio above), and allow it to dissolve fully. Follow the procedures outlined for copper above, and you’ll get a similar effect. Brass is mostly copper, after all.
Stainless Steel
Stainless steel is a bit harder to ‘antique’. It is designed to resist corrosion, after all. However, it is possible. The best method for sheeted stainless steel is lightly scuffing the surface with steel wool or sandpaper. Keeping the sheet flat and level, paint the surface with an acid.
For the lowest grades of stainless, simple vinegar might work – but even this will require several applications. For high-grade stainless, you’d need something much more reactive and also much more dangerous. It might be best to avoid that unless you have special safety training.
Aluminium
Aluminium is relatively easy to age, but the effect isn’t generally as attractive as with the other metals on this list. Just sand the surface, paint it with thick bleach, and leave it in the sun. It should attain an ‘aged’ look in a few hours. Repeat, if needed. Whatever you call it, a bit of artful corrosion can make a piece look amazing. Now you know how to choose suitable metals and use the proper techniques to get the best results.