Stefan Trethan wrote:
> The sad thing is, none of the restrictions is likely to make much
> difference to terrorists, they'll get it anyway.
Yep. Probably by getting a ticket on the Dover-to-Calais ferry, picking up a
few bottles of whatever they want from the continent, then coming back on the
ferry with the stuff hidden under a car seat...
> Maybe you can use lye instead of the sodium carbonate?
Lye? As in sodium hydroxide, the stuff you use to develop PCB photoresist?
Might work, but the real attraction of carbonate is that it's pretty much
harmless (it's used as a food additive, and sodium bicarbonate, aka
bicarbonate of soda, is a derivative of carbonate) and produces less froth,
foam and CO2 than bicarbonate of soda. Plus carbonate is cheaper and better
for dealing with FeCl spills - it's a powder so it'll soak up FeCl and
neutralise it at the same time.
IIRC, the trick is to add the carbonate until the solution is slightly
alkaline, then pour the resulting mess through a coffee filter to catch the
sludge. Pour the liquid away (it's just water and sodium salts IIRC), and
dispose of the filter 'in accordance with local laws' so to speak - that ends
up being covered in fairly pure iron and copper. If you wanted, you could
(theoretically) split that apart and make up a solid copper/iron lump over
time, then sell it to a scrap dealer once you've got enough (note how high
copper prices are these days).
> What does it take to get the required authorisation? Would be interesting
> finding out...
"I don't know" was the answer I got...
I've just been searching about, seems a few local decorator's supply shops
still sell the stuff. Guess I'll be spending this Saturday driving around
looking for somewhere that'll sell me some...
Oh look, £7 +VAT and P&P (£8 +VAT) for five litres:
<
http://www.cfsnet.co.uk/acatalog/CFS_Catalogue__Acetone_7.html>... Saves a
drive round town I guess.
∗expects imminent arrival of the Thought Police and Black Helicopter Squad∗
> But even if it is not difficult, laws like that will kill of the remaining
> chemicals shops (which are only just slightly more commonplace than
> rockinghorse sh∗∗ anyway).
I found a neat article on aluminium anodising
(<
http://astro.neutral.org/anodise.shtml>) that mentioned a site called
TheChemicalShop.com (<
http://www.thechemicalshop.com/>, but mute your speakers
first, at least until you navigate away from the main page - there's a Flash
video on there, complete with incredibly annoying sound effects and recorded
speech). Looks like they sell pretty much anything and everything the amateur
scientist could want, for a price. Ebay seems to be a pretty good source too,
despite their "NO CHEMICALS!" policy... LOL.
I'll have to dig out my copy of 'Electronic Prototype Construction' (the
'Kasten book') and read up on CuCl etching baths. Actually, ISTR that book has
some really 'interesting' (read: dangerous) chemistry listed. Stuff like gold
plating with cyanide compounds...
∗looks∗
Oh, here it is. Page 244. Potassium gold cyanide and citric acid...
And more neat stuff - screen printing the component overlay print...
A little hint from page 310 - if you have to solder an IC socket pin on both
the top and bottom side, use some solder paste to solder the topside, then
solder the bottom side in the normal way (i.e. solder wire)
Shame it doesn't really cover front panel lettering. So far the only way I've
found to put legends on black panels is a Letraset rubdown transfer sheet and
a can of Humbrol spray-on clear-coat. White and aluminium panels are easy - an
inkjet acetate and a can of 3M Photo-Mount usually works for me. It's the
black ones that are a pain, and I've just bought a box full of black 'power
supply' cases (though they're just the right size for USB peripherals and such)...
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