Copper versus Steel for Enameling

Being very new to this I wanted to look at copper versus steel for enameling. Most commercial enamel signs and cases are enameled steel. These normally use a special grade and surface finish steel designed for enameling. In the hobby and craft world copper is the chosen base material. But what are the real differences?

Cost

At a simple level comparing what I can buy on ebay:

  • 0.9mm thick copper sheet 500x500mm £29.73
  • 0.9mm mild steel 500x500mm £8.70

On the commodity markets copper is approximately 7x more expensive than steel at $9740/tonne versus $1350/tonne for steel.

Mass

The density copper is 8.96g/cm3 compared to 7.85g/cm3 for steel. For a 88mm square beer mat, just something I made recently:

  • Copper 0.9 x 88 x 88mm = 62.4g
  • Mild Steel 0.9 x 88 x 88mm = 54.7g

As a base metal blank the copper part is ~14% heavier. Not really that significant.

Forming

Mild steel is a lot harder to form, even cutting out flat blank pieces is tougher. Copper is quite easy to cut out with a pair of hand sheers. It is easy to form if you just heat it up and let it cool to anneal.

However, the benefit with steel is it holds it’s shape better once formed than a copper part.

Cleaning

Before enameling you need to clean the surface of any metal and rough the surface with emery paper to get a good adhesion.

  • Copper:
    • pickling acid or vinegar to thoroughly clean the surface
    • emery or sandpaper to create a surface roughness
  • Steel:
    • alcohol degrease clean
    • sandblasting or emery paper to create a surface roughness

Counter Enamel

For copper you will need to enamel the opposite side to reduce the amount of surface deformation that you will get from firing.

Steel is a lot stiffer and doesn’t require counter enamel. Unless you want the enamel sign to live outside in all conditions.

Base Enamel

In the case of mild steel you need a base enamel that will stick to the steel. The WG Ball groundcoat works really well, it’s like enamel glue.

Conclusion

Copper versus steel for enameling is really down to what you want to achieve. Copper is more easily formed into 3D shapes. Steel is better for flat shapes.

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