I have had a seed-pod cast - in the last bunch I have found that
after soldering wires on to them (making them into earrings) and
taking them out of the pickle they look wonderful - but within 12
hrs they develop a slightly green (greenly/blue) colour to some
parts of them, within the cast silver. Being a seed-pod there are a
few tiny nooks and cervices. I have renewed my pickle and cleaned
each piece in baking soda/water, using a brush to clean them. but
still. it appears.
Anyone have any clues as to what is causing this - or how I could
prevent it. …
The green cast that you see on your pods might be from your pickle. A
simple preventative is to neutralize your work after pickle every
time. Make a solution of common baking soda and water and dip your
pickled objects in the solution, then rinse in plain water.
Regardless of what you use for pickle, Sparex, pH down, citric acid,
it is good practice. I mix a couple of heaping tablespoons of baking
soda to 2 cups of water. This will fizz and bubble when you dump
your pickled objects into it. When it no longer fizzes after multiple
uses, add a bit more baking soda. You can buy large sacks of baking
soda for just a few dollars.
On my solder bench I have pickle, used cold when I’m not in a hurry,
hot when I need to work fast. In front of the pickle pot, I have a
plastic tray that holds a container of baking soda and water, and a
rinse container of plain water. When stuff comes out of the pickle, I
dump the drained pieces in the neutralizing solution all at once,
then scoop them out into the water and then from the water to a clean
towel to drain. I use a plastic basket to make it all easier.
The neutralizing process solves a couple of problems. The first is
the green cast, second it gives you a predictable result when you
have multiple solder steps. Third, it is invaluable when doing hollow
objects. I use a syringe to force the neutralizing and rinse
solutions into the hollow forms, then dry them on low heat on a
coffee cup warmer or for big batches, on a portable electric griddle
set on low.
If you are using a sulfuric pickle, the baking soda solution is
extra important. If you get a bit of that pickle on your skin, a
quick dip in the neutralizing solution will prevent a bad chemical
burn.
I started doing this after reading that you shouldn’t pickle between
multiple soldering. It took forever to get the flux off in plain
water. I reasoned that if I could get the metal back to its original
state, pickling wouldn’t matter. Neutralizing the pickle gets it back
to its starting state on the surface.