Zinc plating

This year I have plated several parts of my coffee machine with zinc to prevent corrosion. This turns out to be surprisingly easy to do at home and I found I already had all the components I needed.

I have plated the bracket which holds the steam boiler in my Gaggia Baby Twin, the bolts which hold the boiler together and the bracket which holds the thermal fuse in place and also acts as a terminal for the earth wire onto the boiler.

In all cases, these ferrous components had rusted to some degree. Living in a very hot and humid or even wet1Because leaks will happen from time to time. environment can do this.

The first step is to remove the rust. Soaking in vinegar is great for this. Also scrub with a toothbrush / wire wool or even sanding depending on the severity of the corrosion. Multiple cycles through the vinegar may be needed.

To electroplate, you need zinc. The easiest source of zinc I found was the casing of a carbon zinc 1.5V cell. i.e. a “cheap battery” as opposed to an alkaline one. We had a few dead ones lying around that hadn’t yet gone to the recycling2I also later found one someone had dumped in the street as litter. I snapped it up with great excitement. I hope no one was watching!. Google for disassembling these cells. They also give you a nice carbon rod and some Manganese Dioxide if you fancy some doing chemistry experiments.

The other components you need are vinegar, table salt3or maybe epsom salts if you’d rather not generate any chlorine and sugar. Also toothpaste is handy for polishing.

For equipment, you need a plastic or glass container of some sort, alligator leads and a power supply (another 1.5V cell will do or any PSU with a similar voltage). An old toothbrush will help with polishing. And gloves for keeping hands clean and preventing skin oils from getting onto the metal.

This is the article I used for the zinc plating instructions. There are others along the same lines if you google. That article explains it well and in full. I’ll just give the basic steps:

  1. Put vinegar in container.
  2. Add the zinc and leave it there for 15 minutes to get some zinc ions in to the vinegar.
  3. Meanwhile polish the part with toothpaste and water.
  4. Dissolve some salt in the vinegar to make an electrolyte4Because we’re doing science, not cooking..
  5. Dissolve some sugar to encourage small crystal growth in the zinc plating.
  6. Attach -ve terminal of power supply to zinc and suspend in the electrolyte using an alligator leads.
  7. Attach +ve terminal of power supply to the part to be plated and suspend in the electrolyte using an alligator leads.
  8. Leave it for 30 minutes.
  9. Wipe the part down (lots of zinc will just come off it – that’s fine.) Polish it again with toothpaste.

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1. Because leaks will happen from time to time.
2. I also later found one someone had dumped in the street as litter. I snapped it up with great excitement. I hope no one was watching!
3. or maybe epsom salts if you’d rather not generate any chlorine
4. Because we’re doing science, not cooking.

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