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Alum Pickle


#1

G’day Terry; As you seem to have enjoyed growing crystals, perhaps
you might try and get some Chrome alum (chromium potassium
sulphate) and make a saturated solution which looks black but is a
deep purple. The crystals of this are exactly the same shape as
those of your alum (potassium aluminium sulphate). so if you take
the most perfect of the chrome alum and grow it on a fine thread,
then immerse it in a saturated solution of alum, you can grow a
crystal that is transparent with a dark purple core. about 50
years ago I grew such a combined crystal about an inch across to
show some young lads that the shape of a crystal is wholly dependent
upon it’s atomic structure. Try some of the other things, like copper
sulphate. But that won’t grow on an alum crystal it has the wrong
structure

Cheers for now,
John Burgess; @John_Burgess2 of Mapua, Nelson NZ


#2

Rushed to the medicine cabinet after reading david thorp on Alum as
coagulant. Anyone with cats, dogs or birds that need nail cutting
keeps a product handy called usually Styptic Powder. Gentlemen often
had a Styptic Pencil on hand for shaving nicks too. Here’s the list
of ingredients in this stuff that works instantly to stop bleeding:
ferric subsulfate, aluminum chloride, diatomite, copper sulfate,
ammonium chloride, iodophor. (For external use.)

Pat


#3

Does the alum pickle solution give the same fine silver plating as
sparex? (The heat, pickle, heat, pickle thing that you do to cover
fire scale and prepare for reticluation?) Tracey


#4
 Does the alum pickle solution give the same fine silver plating
as sparex?  (The heat, pickle, heat, pickle thing that you do to
cover fire scale and prepare for reticluation?) 

Yes. But you should understand that the white matte silver surface
is NOT plating. Nothing is deposited on the surface by the pickle.
The only thing that happens is that the pickle dissolves the copper
oxides. That’s all. In order to get that white surface, you have to
oxidize the copper on the surface for the pickle to then dissolve.
When that happens, any polish on the surface is disrupted, and the
result is that white matte surface. Whether using alum or sparex, if
you put a normally clean unheated piece of silver in the pickle, you
can leave it there till you’re blue in the face, but it won’t turn
matte white. Same thing if you’ve heated, annealed, soldered the
silver, but with a good coat of prips flux on it to prevent
oxidation. If there’s no black oxide of copper on the surface to be
removed, then there’s no resulting matte white surface after
pickling.

Peter