Ask HN: How good is aluminum foil for making a faraday cage?

Ask HN:

I'm trying to go cheap here, but I also need the grounding protection for my experiments. Does anyone here know of a good source for the use of Al foil in faraday cages? We currently use copper mesh, but that is rather expensive compared to foil, and we've put so many holes into the mesh that it is time to replace it (working in electo-phisiology). Thanks for any tips or citations.

Aluminum is fine, but foil that's only a couple hundred microns thick will only provide useful shielding above say 100 kHz. Fine for microwave shielding, but audio frequency EM waves will go right through it.

Also aluminum foil is a pain to work with in many ways. Can you buy a cheap premade aluminum enclosure that's as thick as the copper mesh you have now?

Examples: https://www.google.com/search?q=aluminum+enclosure+electroni...

Then you ground the box same as your mesh is grounded now.

My gut feeling about Aluminum foil is that because of the hard oxide coating it's difficult to get two pieces to make a continuous electrical connection along any length of it. And you can't solder to it.

My suggestion is to use copper tape or thin tinned copper sheet instead.

My other suggestion if hand prototyping is to use vector board with top and bottom ground planes. Note a lot of vector board designs are total crap. Either no ground plane or has 'power buses' The buses are horrible for grounding. The reason is you want the return current in any signal to travel in a ground plane under the wire. with a 'bus' the return current runs off down the bus creating a large loop.

Loops are bad, any magnetic or electrical field that the crosses the loop will induce noise.