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Tacho
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There is hope without cyanide!
Our wise, alert and intelligent administrator mentions a large excess of KNO3, KCl or NaCl in the solution as a way to deposit silver. A quick search
in the usenet groups showed a recipe for cyanide-less silver plating: 3,2g AgNO3, 64g KI and 6 drops of concentrated H2SO4 in 200ml of water.
I decided to do a test using a little bit of AgNO3 in a strong solution of NaCl, and guess what? No, I did not get a shiny layer of solid silver, but
my graphite electrode was covered with a light gray silver coat. It could be wiped away with a paper towel, but I believe it’s a matter of current
density and improved formula.
I used a very large current, and the smell of chlorine was an annoying problem. I think that’s why the formula above uses expensive KI, you don’t
get noxious chlorine, just iodine. Bromine salts may be an intermediate solution.
People also mention that decent copper plating can be achieved using copper sulfate and organics like table sugar. I didn’t notice if they mentioned
some H2SO4.
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axehandle
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I've seen cyanideless electroplating solution in my jewellers supplier's catalog. It existed for both gold and silver. The comp wasn't
specified though.
Still, I'd just cast the retort... Ag is only about 3 times(?) as expensive as Ti.
Edit: <b> Hey, why not take a plain copper retort to a jeweller and have him electroplate it?</b> That shouldn't be too expensive.
The machines I've seen for electroplating are big, expensive and complicated. I doubt a good result could be obtained using homebuilt machinery.
[Edited on 2004-5-14 by axehandle]
My PGP key, Fingerprint 5D96 E09E 365D 1867 2DF5 C2FE 4269 9C19 E079 CD35
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Tacho
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axehandle,
Those are certainly good solutions. But the thing is: electroforming IS (really) useful! Bromic started this thread thinking of a specific task, but
if we could establish a foolproof way to basic electroforming, I believe we will be accomplishing a great task for our collective.
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axehandle
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Tacho, you're right. I plead stupidity. I'm on morphine right now so I'm not 100% clear in the head.
My PGP key, Fingerprint 5D96 E09E 365D 1867 2DF5 C2FE 4269 9C19 E079 CD35
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Tacho
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As I added AgNO3 solution to NaBr solution, the obvious thing happened: AgBr precipitated!
Duh...
I saw no AgCl precipitate in the NaCl solution, although it should have been there! And that deposit on the graphite had to be silver, it sure was not
sodium!
I made a pretty good smooth, solid deposit of copper on graphite using a weak solution of CuSO4 in 50 ml of water, a tablespoon of sugar, ten drops
of 30% sulfuric acid and 2,5V. It took about one hour do it. The CuSO4 solution was light blue, like a swiming pool. Sorry, didn't weight
anything. If the sugar had anything to do with the smoothness, is yet to be determined.
Edit: distance between eletrodes: aprox. 2 cm. No currents were measured.
Copper seems by far the easiest metal do do eletroforming, but I won't give up on silver.
[Edited on 15-5-2004 by Tacho]
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axehandle
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| Quote: |
Copper seems by far the easiest metal do do eletroforming, but I won't give up on silver.
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The price and complexity of the machines I've seen for Au/Ag plating suggest that it's a very delicate process. 
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Saerynide
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Whats the sugar for? 
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Tacho
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| Quote: | Originally posted by Saerynide
Whats the sugar for? |
I have no clue. Information on the net also mention dextrose, gelatin, syrup etc.
I don't know if it's the sugar, but is the best plating I've ever done!
axehandle, you are right. Silver sucks! I give up.
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Cyrus
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The Electroplater's Handbook
For bright copper plating here is a
formula.
No. 3 Bright Copper Bath
30 oz CuSO4
9 oz H2SO4
1 gal dH20
a smidgeon of (NH2)2CS- thiocarbamide/thiourea.
voltage 2-5 volts
The author says to do a test plate,add tiny amounts of thiourea -0.005 oz, then check if the plate is dull, if so, add some more thiourea.
The book seems pretty reliable and he has many electroplating and electroforming formulas for copper, tin, silver, gold, and
even lead- for silverware. 
The book also has immersion plating formulas for zinc and all of the above metals except lead, including a bath with
AgNO3 and NaCl. I thought he was crazy
until the post that said that AgCl did not precipitate? Why not? That bath also had
cream of tartar in it, what would that do?
Is anyone interested in more info?
For making nonconductive surfaces conduct, I have tried graphite powder from a lock lubricant mixed with xylene and polystyrene, but the powder
particles seem too big, and don't conduct. Where do I get finer graphite? Its not like you can grind it up in a mortar and pestle!
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Cyrus
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| Quote: | Originally posted by Saerynide
Whats the sugar for? |
Its supposed to be a brightener, correct me if I'm wrong, but this is how I believe it works. On the object you are electroplating there are
small bumps, and when voltage is applied, corona leakage -is this the right phrase? comes off of these bumps, so that the metal ions in solution are
more attracted to the bumps,
and thus deposit there, making the bumps larger, ad infinitum. Eventually on a small scale your object looks like it's covered in grass- which is
very dull and is a weak coating. To prevent this, we add
brighteners, which have a certain (partial)? charge, and are attracted to the bumps and stick onto them, forcing the metal ions to go to the recesses
and fill those up first. This creates a nice smooth
finish and is SHINY! I love shiny things.
In my recipe, thiourea is the brightener.
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Tacho
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Thank you Cyrus, I’ll try to find or make thiourea.
I did many test baths for copper plating and found out a few things:
1-Sugar does make a difference. In two equal baths, one with sugar, the other without, the plating with sugar holds better, is more solid and better
looking. I haven’t tested anything but sugar as an additive.
2- The worse baths were the ones with too much H2SO4, pH<4. In fact, I believe that has been the major problem with my plating experiments until
today. I found out that acid IS necessary, but in minimum amounts. pH around 5 is excelent. In very acidic baths the deposit is powdery and loose. Is
that more related to current than acidity itself? I have no idea!
3- Voltage has to be kept below 3V. Is that more related to current than voltage itself? I have no idea! Above 3 V the deposit is dark and powdery.
The recipe that gave me best results until now: 10g CuSO4, 30g white sugar, 300ml water and just enough H2SO4 to bring pH to 5. Sorry, the H2SO4 I was
using was of unknown concentration, a leftover, so I have no measures, but be sure that is just a bit, and too much will spoil your bath. The
electrodes were graphite leads (diameter 2mm), imersed about 3 cm in the bath, parallel, 2cm apart, 2,5 V. Current for this setup 10mA. Change in
color in 1 minute, good covering in 15 minutes.
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Tacho
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I think I figured the H2SO4 thing! When you have to plate large surfaces, you need to conduct a lot of current, hence the large amount of acid in the
recipes.
So, I presume that the proportion of acid has to be smaller for small plating surfaces, to prevent excessive current density.
It's either that or something else!
And my initial tests with alginate+graphite are NOT very good. I don't think it will work at all.
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Cyrus
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The thiourea can be bought online cheaply as taste test strips, but I do not know how much there is in the strips.
If you can't get thiourea, use urea, which is the same except for a sulfur replacing an oxygen atom. I doubt urea works as
well though.
With the dull and crumbly deposits, there is too much current density/voltage, and perhaps too much acid. The acid is not added to increase
conductivity, though.
It replentishes the bath so it can be used indefinitely, dissolving the anode to make more CuSO4, but you have to use a copper anode. I need to check
up on the formulas
though.
Why don't you try plating on a substrate other than graphite, because nothing will
adhere that well to graphite- the graphite
will shear off of itself and come away with the copper when you test it for adhesion.
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Tacho
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| Quote: | Originally posted by Cyrus
(snip)
Why don't you try plating on a substrate other than graphite, because nothing will
adhere that well to graphite- the graphite
will shear off of itself and come away with the copper when you test it for adhesion. |
Graphite is used widely to make conductive surfaces from non-conducting ones. I just have not found the right way yet. Besides, I may be expecting it
to detach from the copper layer easily if it is just a mold.
Silver mirror deposit is good only for glass-like surfaces, and electroforming on a mold will require something that can be detached, melted or
dissolved away, like some rubber, paraffin, plastic, gypsum or carbonates.
Somewhere in my fading memories, I see a silver salt being reacted with sulphur-containing gas to create a conductive silver sulphite layer. But I
can't connect the right neurons and this could be just my imagination.
Edit: About the H2SO4, I remember it cleans oxidized copper, so it may improve the deposit by “keeping the layer clean”. I believe, however, that
copper ions will form in the anode with or without the acid.
[Edited on 17-5-2004 by Tacho]
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Tacho
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Ah-ha! I knew it!
I found this in the usenet:
*********************************
From: Zoltan Nagy (nagy@cmt.anl.gov)
Subject: messages from eletqm-l
View: Complete Thread (30 articles)
Original Format
Newsgroups: sci.chem.electrochem
Date: 1998/05/26
*******************************************************************************
The following messages are copied from the e-mail list ELETQM-L. If you wish
to respond, POST a message on SCI.CHEM.ELECTROCHEM. (Please do not use
REPLY/MAIL, as your message will probably be lost. If you want to use mail,
make sure that you use the address of the appropriate message.) All messages
posted on SCI.CHEM.ELECTROCHEM are regularly mailed to ELETQM-L (and vice
versa).
*******************************************************************************
From: SMTP%"mac@encomix.es" 15-MAY-1998 11:44:38.91
To: NAGY
CC:
Subj: Re:
Message-Id: <3.0.1.32.19980516184120.007ac100@encomix.es>
X-Sender: mac@encomix.es (Unverified)
X-Mailer: Windows Eudora Light Version 3.0.1 (32)
Date: Sat, 16 May 1998 18:41:20 +0200
To: eletqm-l@ufu.br
From: Manuel Algora <mac@encomix.es>
Subject: Re:
In-Reply-To: <19980514232307.28464.rocketmail@send1b.yahoomail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
At 16:23 14/05/98 -0700, you wrote:
>
>Does anyone know how to make a good capacitor out of materials around
>the house? Thanks.
>
As long as you may have 2 conducting surfaces and an insulator in between,
you have made a capacitor. For instance, you may use two aluminium foils,
to be put in the outside and inside walls, respectively, of a plastic or
glass container, or a glass sheet. If you use a glass jar, then that's a
Leyden jar. You can also make use of electroplating. The following
procedure comes from the book "Secrets of Building Electrostatic Lightning
Bolt Generators", by Walt Noon (Lindsay Publications, Inc.) First you need
to make the surfaces of the jar conductive, so as to turn them in
electroplating electrodes.
1) Paint the outside of the jar with shellac or any other resin. Let it dry
completely.
2) Paint with (or dip into) a solution of silver nitrate in 50% alcohol.
3) While still wet, suspend the jar inside a larger jar or vessel, and put
some iron pyrite or potassium sulfite in the bottom of this larger jar,
which you then fill with sulphuric acid diluted with 8 parts of water.
Close this "reaction vessel", and hydrogen sulfide phumes shall develop,
which shall turn the silver nitrate coating into silver sulphide. Now you
have a conductive coating on the surface of your to-be Leyden jar.
4) To electroplate this surface, use a solution of copper sulphate in
diluted sulphuric acid, and put you jar inside this solution.
5) Attach the negative of a battery to the conducting surface of the jar.
6) As the anode, use a copper sheet, to be attached to the positive pole of
your battery. The outside of the jar shall be coated with copper.
7) Repeat as per the inside of the jar.
******************************
Isn't hydrogen sulphide that horrible poison that numbs your sense of smell than kills you and has no antidote?
Then I suggest the plating with cyanide!
Just kidding, don't do that!
Edit: How toxic is thiourea by the way?
[Edited on 17-5-2004 by Tacho]
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Cyrus
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Yep, H2S, thats the stuff, Threshold Limit Value of 14 mg/m^3. This the exact method The Electroplater's Handbook suggested.
Thiourea isn't extremely toxic, after all you put the test strips in people's mouths to see if they can taste it.
According to Flinn Scientific, it is a "Possible carcinogen; highly toxic; mild body tissue irritant. LD50 125 mg/kg"
You need a fraction of a gram, so I would be more concerned about the CuSO4,
H2SO4 and H2 gas generated
For making silver coatings on anything, I suggest the following method. It is not as adherent as electroplating of course, or they would all use this
formula, but it may work for hydrazine.
12-3
Tollen's Test for Aldehydes and Ketones
(a.k.a. The Silver Mirror)
Reference: General Chemistry 4th edition by Darrell D. Ebbing, p 1041.
Description: Tollen's Reagent is added to two flasks. A dextrose water solution is added to one and swirled. The contents of the flask turn
brown and then silver is plated onto the inside of the flask. Sucrose is added to the other flask. The contents may turn brown but no silver is
plated.
Concept: Silver (I) is reduced to silver metal by aldehydes but not by ketones.
Materials:
· Gloves
· Goggles
· Two 500 mL Florence Boiling Flasks with rubber stoppers
· Nitric Acid
· Distilled water
· 200 mL 0.1 M Silver Nitrate
· Concentrated Ammonium Hydroxide
· 100 mL 0.80 M Potassium Hydroxide
· 100 mL 0.25 M Dextrose
· 100 mL 0.25 M Sucrose
· 100 mL Graduated Cylinders
· Pasteur Pipettes
Safety:
Nitric acid will burn skin terribly. Wear gloves and goggles.
Acetone is volatile. Do not use near flame. Work in hood when washing flasks with acetone.
Silver is toxic. Wear gloves and goggles.
Wash hands when done handling these chemicals.
Beware: I have heard that silver-ammonia mixtures, if left sitting around can become explosive.
Procedure:
Before Class:
Prepare the Flasks
Rinse the flasks with distilled water, leaving the water in the flask.
Using a pipette rinse the inside of the flask with Nitric acid and then swirl the acid and water in the flask.
Dump the contents of the flask into the beaker.
Rinse the flask with distilled water and dump this water into the beaker.
Using a pipette rinse the sides of the flask with acetone and then swirl the acetone in the flask.
Pour this small amount of acetone down the drain with the water running.
Rinse the flask once more with distilled water.
To both flasks:
Add 75 mL of 0.1 M Silver Nitrate
Pour small amounts of Ammonium Hydroxide to the silver and swirl until the solution is a brown color (muddy).
Pour small amounts of Ammonium Hydroxide to this muddy mixture until it becomes colorless, clear again.
Add 40 mL of Potassium Hydroxide and the solution will become muddy again.
Add Ammonium Hydroxide until the solution becomes colorless, clear again.
In Class:
To one flask add 100 mL of Dextrose. To the other add 100 mL of sucrose
Stopper both flasks.
Swirl the flasks so that the silver will plate more uniformly over the insides of the flasks (the plating will occur in the flask with dextrose within
a few minutes).
Add a scoop of Dextrose to the flask with the sucrose swirl to silver plate it also.
An acrylic spray is available to coat the inside of the flask, to prevent the silver from tarnishing.
Clean-Up:
The contents of the flask that did not contain Methyl Ethyl Ketone can be washed down the drain. The contents of the flask that did contain ketone
should be put into a waste bottle and taken to EH&S collection site as flammable hazardous waste.
Beware: I have heard that silver-ammonia mixtures, if left sitting around can become explosive.
- (Yep, they make silver fulminate,which may be a bonus for some)
Edit: please don't ask me for the formula.
I have no clue.
Notes: This demo is commonly called the Silver Mirror and is done at the Chemistry Open House Magic Show on a larger scale.
Has been used in C102.
[Edited on 17-5-2004 by Cyrus]
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Tacho
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Very straightforward! A good place to learn more about silvering mirrors is amateur telescope making sites. But I doubt any method can be simpler
than the one you posted, although I believe the cleaning can be done using other acids. Nitric acid seems too precious for most in this forum. Water
seems to wet my glassware fine after I put conc. H2SO4 in them, no grease seems to be left.
Common urea is NOT good as a brightening agent, I tried it. I’ll find and test thiourea.
I can’t get the H2S thing out of my head. It seems to be THE way to go to make conductive surfaces out of gypsum, wood and, hopefully, paraffin. I
would appreciate if you could post any additional information you find on the subject.
My goal is to deposit a solid layer of metal on a paraffin mold. I think that would be a very useful trick.
Edit: By the way, your recipe mentions a "smidgeon" of thiourea. Sorry, but how much do you think that would be?
Edit2: A copper electroformed piece can easily be covered with tin or silver, both by imersion in fused metal or by means of simple-to-make
electroless solutions. Maybe both. First chemically cover with thin silver, than carefully melt silver to wet the surface with skill and a blowtorch.
Edit3: Just bought 250g or reagent grade thiourea for the equivalent of U$8 or 6 euros. Seems that it's a common chemical, widely available. I
will test it tonight.
[Edited on 18-5-2004 by Tacho]
[Edited on 18-5-2004 by Tacho]
[Edited on 18-5-2004 by Tacho]
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Cyrus
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| Quote: | Originally posted by Tacho
Common urea is NOT good as a brightening agent, I tried it. I’ll find and test thiourea.
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How much did you try? I would bet you added too much- next time just try a smidgeon!
| Quote: | Originally posted by Tacho
Edit: By the way, your recipe mentions a "smidgeon" of thiourea. Sorry, but how much do you think that would be?
|
No, I don't like the units he uses either, but if I remember right, a smidgeon is the amount of powder that will cover about one fourth of a
square inch, maybe it was a square centimeter, either way, you just feel your way until the plate is shiny.
| Quote: | Originally posted by Tacho
Edit2: A copper electroformed piece can easily be covered with tin or silver, both by imersion in fused metal or by means of simple-to-make
electroless solutions.
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I've got a formula on this too.
1 oz/gal AgNO3
14 oz/gal Na2S2O3
10 oz/gal NH3 (Is it household strength ammonia or pure ammonia?!- probably household. Elsewhere you are supposed to add enough to make the silver
precipitate Ag2S2O3? that forms dissolve.)
Just dip the copper object in.
I do not have any more info on the H2S method, but you also can make a copper or brass mold, and dip the mold in a solution of potassium sulfide -
liver of sulfur, until the mold darkens, and plate on this. The plated metal is supposed to
peel right off. I can check the book out again to get more info.
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Tacho
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You are right about using too much urea, because I had the same results with thiourea. I’m sure thiourea is the right thing because, now that you
mentioned it (thanks!) any search in the net (+plating +copper +thiourea) gives many serious results. I guess, as you said, I’ll have to feel my way
until is shiny.
Just for the record, I used about 2g of urea for a 50ml bath and 0,1g of thiourea for the same volume. Thiourea turned the bath milky, showing it was
way too much.
I tested a method to produce H2S that seems to be the safest, cleanest and... well, the best. I mixed paraffin with sulfur in a test tube (10:1 rate),
heating with a burner caused the bubbling of a gas that turns silver brown. Caveat: careful with the heating, for some reason, everything started
boiling suddenly, causing the paraffin to splatter all over.
Thanks for the silver thing.
A tin electroless plating solution would be stannous chloride and thiourea. There are recipes in the usenet. I will try it soon, but I'll make my
own stannous chloride somehow. Its quite expensive here.
Edit1: This production of H2S with sulfur and paraffin is puzzling.Where does the hydrogens come from? Is the sulfur creating double bonds in the
hydrocarbons? Could it be that I’m making just sulfur vapors? Would these tarnish silver?
[Edited on 19-5-2004 by Tacho]
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Cyrus
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I think sulfur would tarnish silver, but do not know what the reaction you are doing is.
Maybe you could try FeS + 2HCl -> H2S + FeCl2 or something similar with a sulfide.
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The_Davster
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| Quote: | Originally posted by Tacho
I will try it soon, but I'll make my own stannous chloride somehow. Its quite expensive here.
[Edited on 19-5-2004 by Tacho] |
Heres my little route to stannous chloride-all OTC
Electrolyise(I used 2A@12V) a saturated NaCl solution with solder electrodes(60%Sn 40%Pb), tin is preferentially oxidized and if any lead gets into
the solution is is immediatly plated out. Add HCl to the resulting dirty solution, it is black/brown before acid addition. Filter. You now have a
solution of sodium chloride and stannous chloride. Precipitate tin(II) carbonate by addition of baking soda. Filter again. Add just enough HCl to
the stannous carbonate in a beaker to dissolve it all. Let it evaporate. I managed to get a nice pile(5-10g) of nice colorless crystalls, after only
about 30min of electrolysis(plus the rest of procedure) but when I attempted a larger batch the solution turned piss yellow while evaporating for some
reason.
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Tacho
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Thanks rogue chemist, I’ll try that!
I’m trying to make a conductive paint. One of my options is use precipitated reduced silver with some kind of binder.
To precipitate silver from silver nitrate solution, I’m currently testing 4 methods to see which gives the best paint:
1- Hydroquinone – slowly darkens and the precipitate seems grey. Funny, I thought hydroquinone would precipitate all silver at once.
2- Table sugar – Nothing happened in the first hour... Wait... I should have used dextrose, not sucrose!
3- Copper wire – I did this to finally see the famous “silver crystal tree”. To my luck, the silver tree is not beautiful at all, seems to made
of a gray powder that, hopefully, will make a good paint. Its lack of beauty is probably due to tap water ions.
4- Two graphite electrodes and 6 volts – Very black ink-like solution. And guess what? Two mirror spots in the glass! If the tube was very clean, I
guess I would have mirrored (sp?) it completely!
Edit: any idea for a binder will be apreciated. Most binders I used with graphite make it non-conductive.
I'm thinking of gelatin. After dry, I would bath it in formalin, to make it insoluble.
Or very diluted rubber latex.
IMPORTANT EDIT: The solutions posted above have ethanol. I estimate about 50%
[Edited on 21-5-2004 by Tacho]
[Edited on 22-5-2004 by Tacho]
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Cyrus
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If you go to www.pupman.com there are several threads on electroplating on nonconductors.
They suggest using graphite and styrene dissolved in an organic solvent (I believe tolulene.) I tried this, but my graphite particles are disgustingly
large. 
The fine silver idea sounds great,
conductive silver epoxies are made with colloidal silver, try mixing the silver sludge with a little epoxy.
I might try this, except I am making a Vandegraaff generator, and for the sphere, which is more than 1000 in^2. (large I know) this might take a lot
of silver. I first want to electroplate the conductive layer with copper, and then immersion plate it with silver.
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Tacho
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After 24 hours:
1- Hydroquinone – A grey precipitate. Silver powder, too coarse to be black, but good enough to paint. Interesting, though, is the fact that the
liquid left after precipitation had this beautiful golden color. COLLOIDAL SILVER?
2- Table sugar – Nothing happened in the first hour... Nothing happened in the 24 hours after.
3- Copper wire – Probably my silver tree was ugly because I had ethanol in the solution. It was a great disappointment to find out that the
“tree” had this kind of “coagulating” behavior, resulting in chunky pieces of soft silver.
4- Two graphite electrodes and 6 volts – Good black fine powder. I just could not test it for conductivity yet.
About the binder: Epoxy and linen seed oil are options, but I face practical problems in mixing water-wet fine powder with non-polar (oil like)
solvents.
About H2S: The paraffin-sulfur thing, if produces any H2S at all, it’s nothing compared to FeS+HCl. The gas produced by this mix makes the
AgNO3-covered piece of wood instantly very dark. In the other hand, much more danger is involved. Remember: WORSE THAN CYANIDE GAS. FeS is easily made
heating Fe powder and sulfur. The reaction is exothermic enough to make the reactants glowing red. I have not dried the piece of wood yet to test for
conductance.
Cyrus,
I must say with some pride that I discovered the graphite and plastic (styrene) thing by myself some years ago by trial-and-error, like I said earlier
in this thread. I’m not sure what plastic it was, but it worked against all odds, after all, plastics are supposed to insulate. In fact, It was the
only thing I could make work fine until today. But is a thick goo, depending on the coarseness of the graphite, and it’s far from being the perfect
conductive paint.
1000in^2? sounds a big project but, spare me the units conversion, what is the diameter of the thing?
[Edited on 22-5-2004 by Tacho]
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Cyrus
Hazard to Others
Posts: 397
Registered: 24-4-2004
Location: Ancient Persia
Member Is Offline
Mood: No Mood
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To get the silver in a nonpolar solvent, first dry it in a chamber with CaCl2.
Here is my theory on how to get colloidal silver, which I am making up on the fly.
Get a silver salt and mix it with a soluble oxalate salt. Silver oxalate might precipitate, which you then heat up to decompose into Ag and CO2. In
some other thread this method was used to make pyrophoric iron powder.
Yes, my styrene-xylene mix was rather thick too, I wonder if polyurethane would work- I will try and post the results.
The vdg sphere is about 47 cm wide- actually it is not a sphere, the top half is a sphere and the bottom is a donut. I forget the correct name for
this configuration.
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