ethan_c
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Registered: 5-6-2006
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'pen' for electroplating metals
So these things are pretty nifty (albeit fairly overpriced).
http://secure.cartsvr.net/catalogs/catalog.asp?prodid=318676...
http://secure.cartsvr.net/catalogs/catalog.asp?prodid=481002...
I plan on getting the cheaper for a jewelry project- it is quite nice to sort of be able to 'paint' gold on, rather than going with the the
electrochemical cell I had laid out and prepared recently.
First of all, would anyone think that the 'plating solution' would be anything other than gold chloride/chloroauric acid?
But more importantly- wouldn't it be rad to use this little $24 pen thing to plate all sort of metals over all sorts of other metals in a very
portable manner? Setting up plating baths is feasible, but the 'nifty' factor on this thing far outweighs the 'expensive gimmick' aspect. Dipped in
something as common as, say, copper sulfate, this might effectively plate copper metal onto almost anything.
Since I'm getting one, I'll test it soon enough- I'd like to try with silver nitrate, chromic acid (this might be a little trickier)…if it seems to
work for a variety of metal salts, think of the possibilities- one could plate anodes/cathodes with corrosion resistant metals at home for virtually
no cost, instead of trying to find complicated ways around buying expensive commercial ones. With woelen's post on the recent availability on iridium
chloride (ish), how cool would it be to iridium-plate something, eh?
Anyways. Any suggestions/glaring ignorance in this post/naysaying/corroboration/grammatical errors?
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hodges
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I see these on E-Bay pretty frequently for a variety of different metals. Might be a bit less expensive there, and you can pick a cheaper metal such
as copper to get started with.
Hodges
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enhzflep
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ethan_c,
I've used similar units in the past. From our experience, if you wish to do quite a bit of plating then it is well worth it to get one of the units
not so close to the cheapest end of the scale.
I could never understand why on earth something so simple was so expensive. After some discussions with a work-buddy and the dissassembly of some old
pens, I discovered why this was so.
Some of the cheaper pens simply use a gold-plated wire for the eletrical connection to the (synthetic) felt tip. This is absolutely fine, so long as
you've not got the intention of using a plating solution that's particularly nasty. I.e silver, gold, platinum and probably chromium are all out. With
use this plating is dissolved, polluting the colour that you're applying until you are left with a black/copper colour from the copper wire
underneath.
The better pens I've used all utilize a platinum wire for the wet connection to the back of the tip. In fact, the better models have this wire running
down the center of the tip for about 1/2 of its length. This of course means that you're both necessitating the soldering of another piece of wire to
the lead, not to mention the price (and premium) charged for the platinum.
As for plating solutions, I've neither used nor heard of chloroauric acid in the context of gold plating. If you were to use this, be aware that it is
highly corrosive and will chew up the wire that goes into your pen's tip. Though, for hobby use (i.e not several times a day, every
day) this may well not prove to be a problem. Nor do I know if you'd need to add brighteners and hardeners to the solution, I've simply no idea on the
micro-crystalline structure produced by this solution.
At work, we always prepare our own solution, using (to us) cheap and easy to obtain chemicals. Find below some of the recipes from my 'bible'
Typical Gold Cynaide Flash Plating Bath
---------------------------------------------------------
Metallic gold 1/4 troy oz per gallon
Cyanide, Free (KCN) 2 oz per gallon
Phosphate (K2HPO4) 2 oz per gallon
pH 11.8
Current Density 1-10 amp/sq foot
Anode Insoluble stainless steel
Thick Gold Plating Bath
----------------------------------------
Metallic gold 1 troy oz per gallon
Cyanide, Free (KCN) 2 2/3 oz per gallon
Phosphate (K2HPO4) 2 2/3 oz per gallon
Other factors same as above
No Free Cyanide Bath
----------------------------------------
Metallic gold 1 troy oz gallon
Phosphate (K2HPO4) 4 oz per gallon
pH 6.5-7.5
other factors same as above.
Note: all metals in the for of salts (eg Potassium Gold Cyanide complexes) Temperature up around 43C - 65C.
These are some of the formulas from my bible, though I've not used these particular examples. The solution I've the most experience with was even
simpler than pancake mix 
We would take 1L of dist water, add 28gms of KCN drop in 1gm of fine gold(24k, in the form of foil) then simmer until the foil was dissolved. We would
then add up to 2 tsps of NaOH prills to raise the pH. We used this bath cold, with a gold foil anode, adding NaOH periodically to replace the
lost HCN that was formed during plating. 1L of this solution that used 1gm dissolved gold and consumed a 3gm anode would last us over a year, plating
up to 10 objects a day. Alternatively, you could use a stainless anode and add some of the concentrated solution (or it's salts) rather than NaOH. We
used this solution at room temp. It may be worth noting, that pen plating solutions need to be considerably stronger than those used bath plating.
Keeping that in mind, you may want to 1/2 the liquid used in any of the recipes.
I've a 15 pg section in a book (JEWELERY Concepts And Technology by Oppi Untracht, ISBN 0-7091-9616-4) that I could scan if anybody would like more
information. It details reasons for, thickness of, cleaning methods, bath preparation, improvised pen manufacture, and some 18 different plating
solution recipes. It's just a rather large book and scanning would necessitate moving my scanner, which although happy to do, I'd preffer not to
unless somebody actually wanted the info.
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