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Re: Electroplating






On Wed, 2 Sep 1998, Tesla List wrote:

> Original Poster: RODERICK MAXWELL <tank-at-magnolia-dot-net> 
> 
> Good news today! someone sent me a sample of copper sulfate today. I
> posted a message on sci-chem and a company sent me a 1.5lbs sample! Now

Before doing a plating job on something you value, do a few experiments on 
some small test samples. Keep in mind that the current density (as in amps
per square meter) flowing into the object will have an effect on the
quality, as well as the speed of the plate buildup. Using just pure copper
sulfate will not really plate the object, but will build up a spongy layer
that will rub off easily when the workpiece is still wet, but which
*might* be coaxed to stick, once dry. Another poster in this thread 
described exactly this situation. Adding some sulfuric acid to the bath
(Always acid to water, never water to acid!) will cause the formation of 
a solid plate that's smooth, shiny, and, assuming you've properly
cleaned the object and are plating on top of something that's compatible
with the plating bath, will be durable and will adhere well.

{snip}

--OOPS! Snipped off your question on nickel carbonyl exposure symptoms.

Toxic symptoms include fatigue, dizziness, nausea, or unconsciousness.
Chronic symptoms are cancer of the sinuses or lungs, and nickel 
sensitivity, whereby future exposure to even tiny amounts of nickel will
cause rash, blistering and eczema. Once you develop the sensitivity,
you've probably got it for life.

The more "interesting" thing about nickel carbonyl is the concentration
that's considered safe. Since government guidelines are notorious for
being exaggerated, it's useful to compare the nickel carbonyl numbers
with known-serious toxins. Since cyanides were mentioned previously, 
they might make a nice comparison. The recommended maximum exposure
levels of hydrogen cyanide in air are in the 10 parts-per-million level.
For nickel carbonyl, it's in the 1 part-per-*billion* level. Nasty stuff.

By the way, pretty much all nickel compounds exhibit the same chronic
exposure problems. Since the effervescence from plating will spray tiny
amounts of Nickel Sulfate into the air, you'd want to cover the plating
tank thoroughly, and probably do the plating outside, to boot. (If you
spread traces of soluble nickel around your basement, it may not be the
most healthy place to hang around.) Since our bodies need copper as a
trace element, you needn't have similar worries about the copper sulfate,
though you can ingest toxic quantities if you're really careless or stupid
with it.

Hope this helps, good luck, and be sure to share your results!

Wes B.

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