On Wed, 24 Mar 2010 01:34:17 -0700, in rec.crafts.jewelry Jack Schmidling
wrote:

My fork tines are again beginning to show the blueing we previously
discussed so I guess my quick fix with the pickle was just a flash in
the pan.

As I told you beforfe, tarnishing is normal behavior for sterling silver. That
the tines tarnish more quickly than the handles would simply be due to your
casting process leaving a thicker layer of fine silver on the cast surface. And
the areas between the tines, which you say tarnish faster, are simply subject to
less abrasion in use, which normally keeps silver which is used, reasonably
clean.

Pickle removes oxides, not sulphides, which is tarnish. So it would do little
good. That it helped at all would be merely a quick surface effect, not
anything affecting the basic alloy. I'm surprised it helped at all.


My next attempt will be to "temper" the tines. I am thinking just
enough heat to almost get to the "straw color" and then cool. Quench
or air cool will have to be determined.

Jack, Jack, Jack.
Don't confuse silver with steel. With steel, heating to these temperatures
clearely affects the structure of the metal and it's hardness. With silver,
there is no such effect. The only thing you'll do is cause a little oxidation
of the surface (which pickle WILL take off again). And get it over about 750
degrees and you'll start to loose the work hardened temper you got from forging
it in the first place. Once lost, it's gone. You can get some hardening by
heat treating the metal to about 650 to 700F for a half hour, then quenching,
but it's not the same as work hardening, and unless you do it in an atmosphere
controllled environment (which would include proper flux coating with anti fire
scale agents like Prips flux, or others) , you also then get fire scale and fire
stain, both of which willl make your problems worse, not better.

As I suggested before, the behavior of these things is consistant with the sort
of layered surface you get with a lack of control of fire scale and fire stain
in the original making of these. Your fix is simply to have them thoroughly
silver plated. Use a professional plating firm, so as to get a good thick
enough coating. The plated fine silver will be about as resistant to tarnish as
any silver surface could be. If you want better, get them gold plated. Same
deal. Use a pro. Thin gold plating may look good, but it's too thin to give
durability of a resistance to tarnish or fading. I can suggest a suitable firm
if you like.


On a related topic and the subject of this posting...

All of my jewelery that I have gold plated suffer from tarnish of the
silver bleed through and need regular polishing to look good.

And of course, each time you repolish it, the gold gets yet a little bit thinner
too, which makes the situation worse. This is why, done right, gold is applied
over a barrier underplate, usually of nickle, which itself is usually applied
over a copper underplate. That's in part so you can tell when the nickle layer
is thick enough by the color. And the copper adheres to the silver better than
nickle directly does.


My gold plating has been the dip and wear, acid hobby method. Works
great and looks great for a while but the solution has a very short
shelf life. Once the bottle is opened even if only half is used, it
becomes useless within a couple of months. I even tried using a piece
of sacrificial gold as anode/cathode and this did not help.

It wouldn't. The gold anode is only sacrificial in a cyanide based solution. In
other types, it's merely inert. The dip and plate electroless solutions put an
extremely thin layer on. Only a few molecules thick. Once the layer is thick
enough so the underlying silver can no longer react electrochemically with the
solution, the plating stops. This is why it doesn't last very long. And you're
right, the chemistry of those baths is not stable if any oxygen is available.


So I am thinking of making a leap into the professional method and
need to do some research on the subject but the basic question is, and
I think I asked this already but that was a long time ago.... is this
something that one ought to be doing in the home. We read often
enough about people dieing in plating plants.

If you are not comfortable with working with cyanide based plating baths in your
home shop, then don't. But unless you've got children or pets who might not
know to keep away, it's potentially possible for you to learn to work with the
stuff safely. Not recommended officially, of course, but certainly possible. My
own shop is in my basement. I've used cyanide baths on occasion. I know what
I'm doing with them, so I consider myself safe with them. Whether you are,
depends on you. The cyanide baths are far superior to chloride based baths in
terms of quality of the plated layer, thickness, color, and shelf life of the
bath. Most pro platers use them for these reasons. But you can indeed get
non-cyanide based baths. These are acid, based on gold chlorides, rather than
cyanides, so they are much safer to use. Used with a power source, these are
not like your electroless bath at all, and are capable of professional level
plating results. They're a bit more sensative to improper conditions (temp,
voltage, etc), but many people have used them with satisfactory results. Rio
Grande, among other suppliers, carries a good line of such plating baths which
would be safe for a home shop. As I noted, if you want really good gold plating
over silver, also equip yourself with copper and bright nickle baths. Then
you'll need the rest, DC power supply, hot plates, thermometers, electrocleaning
solution, beakers, distilled water, etc.

It's really not difficult to do. But for your forks, I'd still suggest sending
them to a pro. They can do without the underplates (so no possiblity of nickle
sensativity) by putting on a thick enough layer of gold, using a bath that
produces a dense, bright, non-porous layer, so you won't get copper or silver
migrating through a thin electroplate to tarnish. Such a firm could do the same
with fine silver if you wish that instead.

Peter