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Gold Plating Equipment


#1

I’d like to know just what the electroplating process is. I
understand the anodising of reactive metal and I have an anodiser that
we’ve used successfully for years now. But plating’s a whole other
world. Can anyone inform me: What’s required for the power source,
electrically speaking?

I’m hoping I can adapt my anodiser or make a power source here. For
pen plating I assume that the Rio pen equipment is worth buying. Rio’s
catalog describes the pen plating process I’m interested in, but with
our $NZ/$US exchange rate read way over double the price for me. Plus
it’s not 240v.

Brian
B r i a n � A d a m
e y e g l a s s e s j e w e l l e r y
Auckland N E W Z E A L A N D
www.adam.co.nz


#2

Hi Brian: D.C. current is needed for plating.You can get D.C. current
a few ways. The most popular way is to use a rectifier which
transforms A.C current To D.C. current. You can also use anything as
simple as a battery charger from any auto store.They change A.C.
current to D.C. current.You could also just use a car battery since
they are D.C. current.The only thing wrong with the last 2 ways is
that there is no accurate way to control the amount of current
needed.I know a few short cuts.Give me a call and I’ll discuss them
with you. Raymond at Trio Silversmiths 215-925-8746


#3

Recently, I found myself in a situation where I needed a cheap
plating machine. I went to Radio Shack. Picked up a 6V, 900mA/h DC
power supply. You know, one of those power supplies that replace
batteries for portable device that you might wish to plug into the
wall to save on batteries? And a [air of alligator clips. Worked fine
for rhodium. I’m sure that it works fine for gold. Total cost, I’m
sure, was less than $12. Don’t expect to strip with it though.


#4

I’d like to know just what the electroplating process is.

G’day Brian and others; Put simply and reasonably briefly it is the
process where a piece of a pure metal which is to be plated upon
another is place in a suitable solution which conducts electricity,
and the object to be plated, which must also conduct electricity or
have a conductive coating upon it, is placed in the same bath of
solution, called an electrolyte. In the case of plating silver or
gold the electrolyte is usually a cyanide but there are other salts
which are used these days. The piece of pure metal is given a
positive electric charge and the object to be plated is given a
negative charge. Now the atoms of the metal have a natural positive
charge, so are attracted to the negatively charged object.

The electricity may come from a battery, a battery charger, or a DC
generator. It cannot be directly from an alternating current power
supply. The battery charger rectifies it - that is allows the
current to pass in only one direction, and a good charger or plating
unit will have a special circuit to smooth the current properly. The
voltage applied across the plating bath depends upon a number of
variables, but suffice it to say that 6 to 12 volts is usually
sufficient, although it depends upon the size of the object, etc…
The circuit must have a device to control the amount of current moving
the metal ions, and so a device to measure that current in the form of
an ammeter or milliammeter is necessary. If too much current passes
the plating will be coarse, porous and not very adherent. If too
little passes then the plating will be very good, being fine and
coherent, but will take a long time. Temperature control is also
very important, and must be kept constant to a certain degree. Quite
often plating is improved by the addition of a very tiny amount of an
’improver’ which sometimes is a complex salt containing sulphur

I have done electroplating with gold and silver using a battery
charger connected to a 240v AC supply via a light dimmer control,
giving a maximum of 12 volts. I used a milliammeter to show me what
the current flow was like, and I usually plated at around 20 - 25�C.

Plating involves quite a lot of preparation, especially cleaning the
object to be plated and giving it a preliminary ‘strike’ bath before
plating proper begins. There are many books on the subject and I
strongly suggest that anyone who is thinking of doing their own
plating jobs do read up thoroughly on the subject - it isn’t quite as
simple as it all looks at first! > > I’m hoping I can adapt my
anodiser or make a power source here.

An anodiser would probably work quite well, but I have to admit I
have never used one. Cheers, –

John Burgess; @John_Burgess2 of Mapua Nelson NZ


#5

Hi John I have a question. are you using the light dimmer as a rheostat
to control the outcoming energy from the battery charger in the
positive cable just before the ammeter?

Marco


#6

Thanks John. For plating I seem to need a current-regulated supply at
a nominal voltage. My titanium power source is 0 - 240v DC, 1.5 amp
maximum, and the output is voltage-regulated, nominal current. I’ll
need to build a current regulator into it.

    An anodiser would probably work quite well, but I have to admit
 I have never used one. 

It’s a reactive metals anodiser, and voltage-regulated. It uses tiny
milliamperes of current and high voltages, up to mains, and the
colour happens right on the metal. Aluminium anodisers on the other
hand are current-regulated. They use heaps of very dangerous current
to produce the Al oxide on the surface (which is then dyed).

Brian
B r i a n � A d a m
www.adam.co.nz/workshops/bush/
www.adam.co.nz/workshops/street/


#7
    Hi John I have a question. are you using the light dimmer as a
rheostat to control the outcoming energy from the battery charger in
the positive cable just before the ammeter? 

NO!! The light dimmer is connected straight into to the mains 240v
(or whatever) AC supply and the output from the dimmer is connected
to the battery charger input.

Why? Well the light dimmer operates by removing part of the
electrical sine wave of the AC supply, thus reducing power available.
It won’t work on DC; there’s no sine wave!

The milliammeter is then connected in SERIES with the plating cables
so that the actual current being used is measured. If you have a
voltmeter and you want to know what voltage is applied to the
electrodes, you would connect that in parallel - that is, directly
ACROSS the output of the charger. But you don’t really need to know
voltage; it is the current flow which is important.

May I make another thing clear? Well, a rheostat is a variable
resistance which reduces current flow by dropping voltage. This uses
power, and since energy cannot be destroyed, the resistance gets hot
and thus wastes power. So where does the unused energy go in the case
of the light dimmer? Well, that device takes a part of the sine wave
as I mentioned and adds it to another part which has the opposite
charge sign, thus cancelling each other out. Things are a bit more
complicated than that bald statement, but it is true so far as it
goes. And one doesn’t need to get bogged down!

Finally, I might mention that I bought a dimmer that could handle the
power for several lights together, and incorporated that into a
little box with ‘tails’ for standard input plug and output socket. I
use this for several things other than plating or stripping. As I do
wood turning as well as jewellery I have a home made 'poker work’
machine - a short length of nichrome resistance wire which I connect
to a mains/3v ac transformer with high current low voltage output
(bought with a small soldering iron) The AC plug of this is connected
to the dimmer socket, so allowing me to control the temperature of the
nichrome wire ‘hot pen’ to write upon the base of wooden bowls. I
use it for other things too.

Let’s hope I have clarified things, and not added to confusion!
Cheers, –

John Burgess; @John_Burgess2 of Mapua Nelson NZ


#8

“So where does the unused energy go in the case of the light dimmer?
Well, that device takes a part of the sine wave as I mentioned and
adds it to another part which has the opposite charge sign, thus
cancelling each other out…”

Not really. John, most AC Dimmers use a three terminal semiconductor
device called a TRIAC to control the AC load. A TRIAC has three
terminals, Main Terminal 1, Main Terminal 2 and a Gate. It works by
applying a control voltage to the gate. The source and load is across
the MT1 and MT2 terminals. Varying the control voltage turns the
TRIAC on and off at different points along the AC cycle. As more of
the AC cycle is switched out (or turned off), less power is allowed to
flow to the load. It is the dimmer control that varies the control
voltage to the gate. Therefore, dimming action is a result of parts
of the AC cycle being cut off by a high speed switch, the TRIAC. It
is the power rating of this TRIAC that sets the wattage rating of the
dimmer.

By the way, dimmers such as these can only be used on resistance
loads like incandescent lamps and soldering irons. Inductive loads
such as transformers and florescent lights cannot be used. With
inductive loads the voltage and current are not in phase with each
other, and thus will not turn the TRIAC off correctly.

Charles Heick
Cincinnati, Ohio


#9
    "So where does the unused energy go in the case of the light
dimmer? Well, that device takes a part of the sine wave as I
mentioned and adds it to another part which has the opposite charge
sign, thus cancelling each other out..." 

G’day Charles; I completely agree that this is not correct, and I
had second thoughts as soon as I posted it! I had indeed forgotten
about triacs, but my main purpose was to try and simplify things as
much as possible - and I succeeded in making it too simple. that was
rather nonsense - ‘put brain into gear before engaging mouth (or
fingers)’

    By the way, dimmers such as these can only be used on
resistance loads like incandescent lamps and soldering irons. 
Inductive loads such as transformers and florescent lights cannot be
used. With inductive loads the voltage and current are not in phase
with each other, and thus will not turn the TRIAC off correctly. 

I think that I will have to shut up a bit more! However, I do use a
dimmer with a battery charger to give a fine control over the current
flow for some things, such as when I am using it for plating or for
driving my home made vibro polisher - which in the main part consists
of an old dust buster DC motor. And that charger does have a
transformer to drop the voltage before rectification. I also use a
dimmer in front of an old 240/3v transformer for writing on my wood
turning jobs with a bit of hot nichrome wire. BUT: doesn’t the
dimmer ‘think’ the primary of a transformer might be a resistance? I
think it is that which had me confused and ‘non thinking’ Anyway -
Thank you for your polite correction - I appreciate it. Cheers –

John Burgess; @John_Burgess2 of Mapua Nelson NZ


#10

So whats the deal with using a control dimmer anyway. In this case I
can’t see any difference between a rheostat and the dimmer in
question. Well let me try to get it straight, I understand the light
dimmer is for AC current and the rheostat is to be used with both AC
and DC isn’t it? well in this case is more important to control the
outcoming amperes from the battery charger cause the voltage is
going to be constant(12volts) and proportional to the amount of
electrolyte in the bath,so why to control the energy going in the
charger? Marco


#11

Marco, You are actually controlling the voltage into the transformer
of the battery charger. Since voltage and current are directly and
proportionately related to each other, by raising or lower the applied
voltage you are directly controlling the current output.

Lester…


#12

John, it’s been quite a while since I knew this for certain, but my
memory says that you are correct here. The transformers you mention
are straight through connections to the line, without and series or
parallell connections to a capacitor/capacitance. My recollection is
that without a capacitance or additional resistance in the circuit,
the coil of the transformer doesn’t significantly alter the voltage to
current phase of the incoming power. and as I recall, the key word
here is “significantly”. In short, in those uses, the triac will
still function reasonably well as a controller. At least, that’s how
I remember it. Anyone else know better?

Cheers
Peter Rowe


#13
    I can't see any difference between a rheostat and the dimmer in
question. ... I understand the light dimmer is for AC current and
the rheostat is to be used with both AC and DC isn't it? well in
this case is more important to control the outcoming amperes from
the battery charger cause the voltage is going to be
constant(12volts) and proportional to the amount of electrolyte in
the bath,so why to control the energy going in the charger? Marco 

G’day; You don’t HAVE to control the energy going in to the charger,
providing that you don’t want to vary the power (amps x volts) coming
out of it. If you do need to vary the power - say for plating, then
you could control the current coming from the charger and going into
the bath by means of a variable resistance (rheostat) The amount of
current to give a good plate would vary but little if all other
parameters were kept constant (electrode & object size and distance,
bath concentration and temperature) You would only need to set it at
the start to give the sort of plate you want, then just let it go
along, providing the bath is continuously stirred. But if you need a
certain current density (amps per square centimetre - which is how
plating is measured) then you have to set it properly at the start.
One way of doing this is to limit the voltage across the DC supply
(charger, etc) by means of a rheostat, or a variable transformer or -
yes, a light dimmer. As the voltage across the input falls, so will
the output voltage fall, and controlling the voltage enables the power
output to be controlled,

Clear as mud? Cheers anyway.

John Burgess; @John_Burgess2 of Mapua Nelson NZ


#14
But if you need a certain current density (amps per square
centimetre - which is how plating is measured) 

A-hah. So amps per square centimetre is the primary factor in
plating, right? My titanium anodiser is a huge variable transformer 0

  • 240v with DC output, and easily able to be set and adjusted at a
    certain (rather low) voltage range. I have an ammeter fitted. Sounds
    like I could use my titanium anodiser as a power source, then.

What do I need now for pen plating? A plating pen, non-cyanide
electrolyte, and 24k?

Brian

B r i a n � A d a m
Auckland NEW ZEALAND


#15

Autotransformers (your variable transformer is one ) can be
dangerous. By themselves they offer no isolation from the incoming
power system. Working with pen plating could be terminally exciting .
I don’t know what you have but if there is not a second two winding
transformer in front of the variable one don’t use it . You only
need a few milliamps for pen plating! This will be below the range
of an ammeter. Jesse


#16

Power Factor is a product of both resistive and reactive loads. A
reactive load may be either an inductor or a capacitor. A resistive
load contains only a resistive component. An reactive load contains
both a resistive and inductive or capacitive component.

If you connect AC across a purely resistive load, current will flow
and be in phase with the voltage. Power in this case is measured in
watts (real power) and is the product of voltage (in volts RMS) times
current (in amperes). For a resistive load with one volt across it
and drawing one ampere of current, there is one watt of real power
being used. An example of a resistive load is an incandescent light
bulb.

If you connect AC across a purely inductive load, the current will
either lead or lag the voltage by 90 degrees. At a particular instant
in time, the voltage will be negative while the current is positive or
the voltage is positive while the current is negative. This means
that during any instant in time, the energy is actually being
transferred back from the inductor into the voltage source. An
inductor stores energy. For a purely inductive load with one volt
across it and one ampere of current flowing, the power is 1 VAR
(reactive power). Inductive power is not measured in watts, but in
VAR or Volt-Amp-Reactive. A pure inductor produces no heat, unlike a
resistive load. An example of an inductive load is a transformer.

In the real world, an inductive load is made up of both a resistive
and inductive component. The resistive component is drawing current
in phase with the voltage, while the inductive component is drawing
current 90 degrees out of phase with the voltage. The resultant Power
Factor, or PF, is the instantaneous summation of these two currents
and is somewhere above zero, but less than 90 degrees. It separate
measurements are made of the voltage and current, the product is not
AC power as is the case with a purely resistive load or DC. Power is
calculated taking into consideration the phase of the voltage to the
current and is also measured in VA (apparent power). Apparent power
is the vector sum of real power and reactive power. PF is equal to
the real power divided by apparent power.

AC Watts = Voltage x Current x PF (cos theta) PF = Watts / VA

An inductor such as a motor winding affects PF as much as a capacitor
can. The difference is that a motor winding produces lagging PF since
the current lags the voltage, while a capacitor produces leading PF
since the current leads the voltage. Since most of the worlds power
load is inductive, electric utilities need a form of power factor
correction. This lagging PF is corrected by placing capacitors on the
power lines. This is done in substations or by capacitor banks
mounted on utility poles.

A TRIAC is affected by this PF. Since the voltage and current are
out of phase on an inductive load, it will not turn off completely.
Also, high voltage inductive spikes can damage unprotected
semiconductor devices such as a TRIAC.

The difference between a rheostat and a dimmer is how they control
the power. A dimmer simply switches out the load. As more of the AC
cycle is switched out, less and less power is delivered to the load.
A rheostat does not switch off the load, but reduces both the current
and voltage going to the load. However, it is very inefficient for it
must absorb whatever power is held back and dissipate it in the form
of heat. For either device, the power ratings must be taken into
consideration.

I hope this helps.
Charles Heick
Cincinnati, Ohio


#17

Excuse me, but I must make a correction to my last posting on Power
Factor. As I re-read it on Sunday, I noticed this error�

“If you connect AC across a purely inductive load, the current will
either lead or lag the voltage by 90 degrees.”

It should read: If you connect AC across a purely REACTIVE load, the
current will either lead or lag the voltage by 90 degrees.

Additional note: A reactive load can be either inductive or
capacitive.

Sorry for any confusion.

Charles Heick
Cincinnati, Ohio