emi rfi compliance with wood

seems that most dried wood is non conductive so wood does not shield well for rfi or emi
hmmm might have to add a layer of thin metal on the inside to minimize leakage
copper always looks good but i wonder if the patina that develops will change the way it shields
maybe there is a wood that has some conductive qualities even in the dried state
faraday tree
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On Thu, 30 Jun 2016 18:11:54 -0700, Electric Comet

Ironwood?
Seriously, if you insist on such nonsense, use a separate shield or metallic paint on the interior. A better solution is to design what's going inside such that it doesn't need shielding.
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On 6/30/2016 9:11 PM, Electric Comet wrote:

company that sells stained-glass supplies. I've never seen it in sizes over 12"X12" but if one looked hard enough bigger stuff is probably out there. If using small sheets joining them together is easy with a bit of flux and solder. Back in ancient days when I occasionally built wooden enclosures for rf-sensitive audio gear I used similar foil for shielding and in the wooden computer case I built I covered everything inside with copper. My foil was bought in Japan and was, at a guess, 60cm wide and 10m long but had no adhesive backing and had to be glued down with contact cement.
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wrote:

Foil is also available with a conductive adhesive. I used it at a PPoE to try different shielding techniques. The eventual solution was conductive (nickel-filled) paint.
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You guys are overthinking this. Copper is expensive overkill for shielding. Grocery-store aluminum foil works fine and you can stick it down with hot glue, double-stick tape, contact cement, or whatever else you like. If you have an opening you need to shield, aluminum screen from your average hardware store is plenty for the sort of openings you typically find in computer cases--it's better than what is used in most store-bought computers.
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On 7/2/2016 4:48 AM, J. Clarke wrote:

But aluminum foil will not develop that blueish green patina over time like copper will.
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On Sat, 2 Jul 2016 05:48:06 -0400, "J. Clarke"

The problem with aluminum foils is that the seams have to be connected. Aluminum quickly forms an oxide that's non-conductive. Since aluminum, (particularly foil) doesn't solder well that doesn't help, either. If you can solve the seam problem, aluminum is excellent.
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LOL at faraday tree. Trees are good conductors of lightning discharges, but otherwise I can't think of one that conducts.
RFI/EMI is a difficult subject. You need a conductive material, and any gaps or holes have to be smaller than the wavelength of the signal you're trying to contain (or block out, as the case may be). Unfortunately, that means the holes/gaps have to be small in both directions - a long, thin gap like you might get at the joint of a lid and a houseing can be an excellent radiator of RFI.
You could put solid metal sheet (copper, aluminum, steel) in as a shield, or metal mesh/screen, or conductive paint. Whatever you use has to be well grounded to your circuit ground to work well for EMI. This can be a problem with paint. Tarnish on copper is only a problem if it prevents a good ground path from existing.
Any wires that come out of your enclosure can be excellent conductors of EMI/RFI, including the power cord. RFI can usually be solved with a small cap to ground, but it can be a real bear getting EMI off a power cord.
Beware that if you have an oscillator running at high freqs (100 MHz, say) and your shielding is close to it and not very rigidly fixed, it can detune your oscillator and cause various weird problems.
John
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On Thu, 30 Jun 2016 18:11:54 -0700

decided to make two enclosures
the first one will enclose the device then i will place a copper mesh over that the second box will enclose the mesh and the first box
this way it will look like a solid wood enclosure
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On Mon, 11 Jul 2016 18:52:39 -0700, Electric Comet

as small as possible. This can be a real PITA, without the complications of your Russian doll. Conductive paint is a whole lot easier. ...almost as easy as punctuation and starting sentences with upper case characters.
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On Mon, 11 Jul 2016 22:14:55 -0400, snipped-for-privacy@attt.bizz wrote:

Better yet make a faraday cage.....
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