Subject: Ni plating- why dull finish?

From: [email-masked] (Christopher McDowell)
Date: 23 Mar 1994 17:47:17 GMT

I've been Nickel plating some small parts, and the surface finish is
always dull.  Is there some way of achieving a shiny surface?  I use 
some Ni salts, maintain the pH between 3-4, and temp is 40-60 deg C.
the parts are a couple os sq cm., and I use about .5 amps.  The finish is the
same regardless of plating time.

	Thanks,
Chris McDowell

	Disclaimer- The mgmt couldn't agree with me more.

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From: [email-masked] (Chris Helt)
Date: Wed, 23 Mar 1994 22:32:43 GMT

Christopher McDowell ([email-masked]) wrote:
: 	I've been Nickel plating some small parts, and the surface finish is
: always dull.  Is there some way of achieving a shiny surface?  I use 
[snip]
: 	Thanks,
: Chris McDowell

I have had many parts Nickel plated.  Most places ask if I want "as plated"
(dull) finish or polished (extra $ because of extra (polishing) step).  This
implies to me that (at least the type of Nickel plating I have been getting)
is a dull finish but can be polished after plateing to give a bright finish.

Chris Helt

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From: Doug White <[email-masked]>
Date: Thu, 24 Mar 94 09:03:11 -0500

> 	Disclaimer- The mgmt couldn't agree with me more.
I'm no expert, but when I've had 'bright' nickle plating done, they always 
start with a fairly heavy copper plating, which they buff to a bright shine.
This provides the right surface for the nickel to stick to and gives a 
polished finish.  By the way, NEVER use an ammonia based polish on nickel
plating.  Most modern nickel platings are porous to the ammonia, and it
reacts with something and leaves a cloudy finish after a while.

Doug White
MIT Lincoln Laboratory

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From: [email-masked] (Chris Kapral)
Date: Thu, 24 Mar 1994 15:28:26 GMT

>same regardless of plating time.

Are you making your own solution?  I nickel plated some small parts using a solution 
from a company called Vigor, and they came out pretty shiny.

Any small surface scratches will be magnified by plating, so the result will usually 
be less shiny than what you started with.  There are "bright" plating solutions that 
have additives to counteract this effect.  Maybe my Vigor solution was this type.

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From: [email-masked] (Robert Mitchell)
Date: Thu, 24 Mar 1994 16:32:21 GMT

>> always dull.  Is there some way of achieving a shiny surface?  I use 
....
>polished finish.  By the way, NEVER use an ammonia based polish on nickel
...

I am getting ready to experiment with "electrolis" nickle plating
on my own.  I am replating old nickle over steel (watchmaker stuff).
What surface preparation should I do?  I did not intend to
copper plate...
 - Thanks - Robert Mitchell
-- 
UUCP:  [email-masked]
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From: [email-masked] (Christopher McDowell)
Date: 24 Mar 1994 18:28:22 GMT

Attn Rod Barman (et al)

	I tried to mail you back but got bounced.

	My samples are stainless steel, highly polished.
the recipie I use is:

	1.5 L distilled H2o
	500 g Ni sulfate hexahydrate
	80 g Ni chloride Hexahydrate
	64 g Boric Acid

	Boric acid added as necessary to bring pH to 3-4
	Final vol. of soln is 1.8 L

	I use nickel foil as an electrode, held in place with nickel plated
steel alligator clips.  I use .5 amps, voltage comes out to be something like
2.5 volts ( the power supply works on a constant current).

	Thanks to anyone who can help!

	Chris McDowell

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From: [email-masked] (Dion Hollenbeck)
Date: Thu, 24 Mar 1994 20:41:32 GMT

>>>>> "Chris" == Christopher McDowell <[email-masked]> writes:

Chris> 	I've been Nickel plating some small parts, and the surface
Chris> finish is always dull.  Is there some way of achieving a shiny
Chris> surface?  I use some Ni salts, maintain the pH between 3-4, and
Chris> temp is 40-60 deg C.  the parts are a couple os sq cm., and I
Chris> use about .5 amps.  The finish is the same regardless of
Chris> plating time.

Plating is much like computers - Garbage In, Garbage Out.  In other
words, the plating will never be any smoother than the substrate.  If
you want a smooth finish, you must buff the original substrate as
smooth as you want the plated finish.  It is also possible that you
are dulling the surface by your plating technique.

-- 
Dion Hollenbeck (619)675-4000x2814     Email: [email-masked]
Staff Software Engineer     Megatek Corporation, San Diego, California

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From: [email-masked] (Clive Washington)
Date: Fri, 25 Mar 1994 10:28:10 +0000

In article <[email-masked]>, [email-masked] (Dion

> are dulling the surface by your plating technique.

This seems to be related to the technique known as electropolishing,
which I have heard of, but I don't know what it involves.  Does anyone
out there know anything about it?  If so, could they enlighten us?

Thanks

Clive W.
-- 
!!!According to my contract, this place owns my opinions!!!

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Article: 4303 of rec.crafts.metalworking
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From: [email-masked] (Russ Kepler)
Subject: Heat treat ovens
Message-ID: <[email-masked]>
Sender: [email-masked] (Russ Kepler)
Organization: Russ's home for wayward hackers
Date: Fri, 25 Mar 1994 05:05:23 GMT
Lines: 22

Now that I've got my 4130 problems sorted I've get a follow-on
problem: I need to heat treat my 4130.  For this I've been looking at
a couple of different ovens.  Paragon, in Texas, seems to have a nice
little line of burn-out and heat treat ovens.  The smallest of their
programmable ovens could work well, but is a bit pricey at $700 or so.
Brownell's lists a small oven from Neycraft similar to Paragon's low
end burn-out oven for a bit morem but building a programmable
controller is a simple matter anymore, and I believe that I could do a
nice job for very little.

Who have I missed?  I'm looking for a 300degf...2000degF oven with a
9-14" capacity, 120V at no more than 20A.  There's got to be a few
more makers out there...

As long as I'm asking about heat treatment, what do folks pay for heat
treating a knife blade?  Would it be worth it to me to do simple heat
treat to help pay for the oven?  

-- 
Russ Kepler posting from home  [email-masked]

                      Please don't feed the Engineers

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From: [email-masked] (Christopher McDowell)
Date: 25 Mar 1994 13:36:08 GMT

Clive Washington ([email-masked]) wrote:

: This seems to be related to the technique known as electropolishing,
: which I have heard of, but I don't know what it involves.  Does anyone
: out there know anything about it?  If so, could they enlighten us?

	Electropolishing involves a stream of acid impelled towards a specimen/
target.  The specimen is positively chrged, and the chemical action of the acid
knocks atoms from the surface which are then repelled by the pos. charge of the
specimen.  
	Then there is electroetching, which is basically the same thing but 
with a weaker acid soln.  Electroetching is used to reveal microstructural 
details, while electropolishing is often used to thin metal specimens down
for Transmission Electron Microscopy. I don't think either process is used to 
brighten surfaces.

	Chris McDowell

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From: [email-masked] (Dion Hollenbeck)
Date: Fri, 25 Mar 1994 16:25:10 GMT

>>>>> "Chris" == Chris Helt <[email-masked]> writes:

ChrisH> Christopher McDowell ([email-masked]) wrote:

ChrisM> I've been Nickel plating some small parts, and the surface finish is
ChrisM> always dull.  Is there some way of achieving a shiny surface?  I use 
Chris> [snip]
ChrisM> 	Thanks, Chris McDowell

ChrisH> I have had many parts Nickel plated.  Most places ask if I
ChrisH> want "as plated" (dull) finish or polished (extra $ because of
ChrisH> extra (polishing) step).  This implies to me that (at least
ChrisH> the type of Nickel plating I have been getting) is a dull
ChrisH> finish but can be polished after plateing to give a bright
ChrisH> finish.

Yes and no.  Polishing is almost always done *before* plating.  To
polish after plating, you have to put on a thickness of plating which
is extraordinarily heavy so you do not run the risk of polishing
through it.  When you put on heavy layers of plating, it can easily
get pebbly and build up excessively on corners.  Having a polished
substrate will result in a polished finish, unless you screw up in the
plating by applying the wrong amount of current, having an unbalanced
solution, or leaving it in too long.

The only post-plating work generally done with a wheel is
"color-buffing".  This is done with a very soft buff and fine rouge.
When the piece comes out of the plating step. sometimes it has a
rainbowy effect in places and color buffing is used to remove this
"haze" from the surface of the metal.  Again, it is easy to cut
through the plating.  Most plating is cosmetic.  By that I mean that
it is meant to 1) prevent corrosion by sealing the surface with a
metal which does not corrode easily and 2) provide a pretty surface
look.  Very little plating is done to actually build up the surface of
the metal (other than hard chrome) and as such, cosmetic plating is
*very* thin.

There is one notable exception to pre-plating buffing, but it is
*in-between* plating buffing.  If you want to do an absolutely mirror
finish, the best way to do it is to polish the surface as for normal
plating preparation, copper plate it until a *very* thick layer of
copper has built up and then buff the copper until it is mirror
smooth.  Copper can be smoothed out lots easier that the base metal.
Now that you have a mirror smooth base, go back into the copper bath,
strike it momentarily to get a couple of atom thick layer of fresh
copper on the surface, nickel plate it and then chrome.  The nickel is
generally the layer with gets the most thickness, with the chrome
being *much* thinner and only cosmetic.

BTW, polishing is done with abrasive belts or stiff buffs with
abrasive compounds, buffing is done with soft buffs and fine
compounds, the two processes are very different.

The above is not mere speculation or second hand knowledge, I worked
in my father's electroplating business fulltime summers while going to
high school.  We did everything from car bumper chroming to MIL-SPEC
gold and silver, anodizing of aluminum and blackening of steel.  I did
a lot of plating myself as well as polishing and buffing.  Some of the
switch contacts which we gold and nickel plated for Kinetics Corp. are
now sitting on the moon in the lunar lander.

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From: [email-masked] (Carl F. Ijames)
Date: Fri, 25 Mar 1994 20:52:08 GMT

In article <[email-masked]>,

> out there know anything about it?  If so, could they enlighten us?

Electropolishing is performed like electroplating, but with the current
reversed.  The work is the anode, and metal is removed.  Because the
electric field is enhanced at sharp protrusions, and the metal removal rate
is proportional to the electric field, the surface is smoothed (polished)
as metal is removed.  Lead is usually used as the cathode, and the
electrolyte is mostly mineral acid (solutions of sulfuric and phosphoric
acid for stainless steel, for example).  The electrolyte serves to carry
the current and to solubilize the metal ions.  Current densities are on the
order of an amp per square centimeter (smooth film of bubbles but not
vigorous "boiling" at the surface to be polished).  I've played (er,
worked) with several small pieces of stainless steel in the lab, and had
decent success.  Sharp edges will be slightly rounded, and threads need to
be protected so they won't be etched away.

Carl Ijames     [email-masked]

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From: [email-masked]
Date: 25 Mar 94 21:15:54 CST

> 	Disclaimer- The mgmt couldn't agree with me more.
I would suggest that you go to the Engineering Library or where ever the Metals
Handbook, published by the American Society of Metals, is kept. Volume 2, Heat
Treating, Cleaning and Finishing, has a good section on nickel plating.  It
specifically refers to bright plating.  Also you might try adding a little soap
in your plating bath- it's an old trick for getting a smoother finish.  Copper
underplating helps adhesion with metals like iron, nickel and zinc. 
 m

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From: [email-masked] (Nigel Patrick Gore)
Date: Sun, 27 Mar 1994 01:58:15 GMT

Sorry I can not find all the details at the moment but generally;
There are two types of electro plate bath for nickel and one electroless 
the bright type uses brighteners which may be organic and the supplier regards 
as a trade secret. 

Hope that makes sense.
N.
.

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From: [email-masked] (Richard C Lucas)
Date: Tue, 29 Mar 1994 23:53:36 GMT

My recollection is that there are "brighteners" which are added to plating
baths to cause the plated film to be highly polished.  Protrusions, corners,
edges, tend to concentrate the current in the plating bath.  This is caused
by two effects; the field concentration, and the thinning of the diffusion
layer at the corner.  In the plating process, the rate is determined by the
current density, which determines the average plating rate, and the diffusion
of metal ions across the stagnant layer (diffusion layer) at the surface.

Brighteners are usually large organic molecules which get "dragged" across the
diffusion layer by the flux of metal ions.  The  organic molecule gets
deposited at the high flux areas effectively poisoning the plating at that
point.  The effect is that the plating rate becomes more uniform.  Urea is a 
common leveler.

Dick Lucas