Roxanne Hunnicutt on mon 4 jan 10
t sure is not. I have some serious flaking
I think I asked this before but please be patient. ARE PEOPLE PAYING peter
pugger to get the coating on their pug mills? HOw much. I sure think P
Pugger should fix this flaking problem! I was assured that porcelain use
would be fine and it sure is not. I use porcelain intermittently only.
I have sent them pictures of my barrel and it looks like a serous case of
adolescent acne. And changes in the acidity of my clays does not seem to
help.
I have cleaned it and tried to scale it and started all over again with cla=
y
that was supposed to be balance with epsom salts and that did not seem to
fix the situation.
This is so frustrating, to pay so much and to get such a problem with no
easy solution.
Have they subsequently changed the metal formula for new pug mills? Has any
legal means been attempted to resolve this? Rox on OREGON who seriously lov=
e
the machine otherwise!
ivor & olive lewis on sat 9 jan 10
t sure is not. I have some serious flaking
Dear Roxanne Hunnicutt,
I think Steve Graber is getting close to an answer as to why the corrosion
happens and the solution to the problem that he suggests may be possible.
Little has been said about the chemical properties of the materials
involved.
Metallic Aluminium is attacked by both acids and bases. With acids it forms
salts such as Aluminium sulphate. With stung bases it fomes Aluminate
compounds such as Sodium Aluminate.
Aluminium Oxide has the ability to react with both acids and bases. It is
classed as an Amphoteric substance, behaving towards acids as a base and
towards bases as an acid.
Anodisation is a way of using a strong oxidising solution and an electric
current to build up a thick layer of Aluminium oxide from the metallic
surface. This is not a coherent layer but one that is porous. Its usefulnes=
s
comes from its durability, a resistance to abrasion. Because it is a porous
layer it can absorb dyestuffs and is given a decorative colour. But it is
not resistant to attack by Alkali solutions.
Values for the concentration of alkali solutions that form when KNaO
felspars are mixed with water over a long period are given in J. C. Kyonka
and R. L.Cook, "The properties of felspars and their use in whitewares".
Beside Electroplating with Nickel for corrosion resistance under an overcoa=
t
of Chromium for wear resistance, Plasma spray coating with one of the Cobal=
t
or Nickel corrosion resistant hardsurfacing alloys might be worthwhile.
Best regards,
Ivor Lewis,
Redhill,
South Australia
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