John Kudlacek on tue 12 apr 05
Anyone,
Recently I was asked if one could apply metalic luster to a raku piece
that had been "smoked" after the fire. The question posed was "would the
firing of the luster burn off the carbon on the pot?" A question of my own
is, "would the carbon in the piece affect the efficacy of the luster?"
Now, about sieves: I recently screened some malochite through a 60 mesh
sieve. Some of the malochite remains imbeded in the screen. Anyone know
a way of removing these particles without damage to the screeen? I used
the sticky side of duct tape and removed the majority of it but still some
remains.
Thanks.
John Kudlacek
Topeka
jesse hull on tue 12 apr 05
John,
your carbon will go bye-bye. 1200+degF is hot enough.
If you're talking about crackle darkening, you can
always use india ink and the like. But when I used to
raku, I always liked to darken the crackle in the
earlier stages to get the big broad lines rather than
the tighter web-like ones that formed later.
If you're talking about a copper matte (rainbow
pattern), etc. all your colors will be gone or
seriously muted.
As for your sieve, you can use a pressure washer. Or
try forced air from an air compressor... bottled air
might work, but I doubt it. Take the air gun right up
to the embedded particle, -and wear eye protection.
~jessehull.
Logan Oplinger on fri 15 apr 05
On Tue, 12 Apr 2005 09:20:19 -0400, John Kudlacek wrote:
>Anyone,
> ..... Now, about sieves: I recently screened some malochite through a 60
mesh
>sieve. Some of the malochite remains imbeded in the screen. Anyone know
>a way of removing these particles without damage to the screeen? I used
>the sticky side of duct tape and removed the majority of it but still some
>remains.
>Thanks.
>John Kudlacek
>Topeka
>
Hello John,
As Bruce has said, a good stiff scrub brush works well. This works best by
using the brush on the back side of the sieve. Once in a while though I
have had problems with using just a scrub brush. Another method is to turn
the dry sieve upside down on a table, and with some force (not enough to
damage the frame), hit opposite sides of the sieve frame simultaneously
with the flat of both hands. After each hit, rotate the frame a bit and
hit again. About 10 to 15 times will remove most grains that can be
removed this way.
Occasionally, if I want to remove any trapped grains of material that may
cause discoloration of a clay or glaze, I have resorted to a method that is
highly discouraged by those who use sieves for doing particle size
analysis. For sieves having an opening of 60 mesh or larger, and with the
aid of a magnifying glass, I have used a fine sewing needle with gentle
pressure on each grain from the back side of the sieve. This will take
time but is effective. ***CAUTION!*** By using this method you do run the
risk of deforming the sieve wires and causing the openings to become larger.
Finally, you say the material that remains trapped in your sieve
is "malochite". If you mean "molochite", this is calcined alumina silicate
mineral, sometimes used as grog, which is insoluble in dilute acid.
If, however, you do mean "malochite" or "malachite", this is a green copper
mineral which is a carbonate. Most carbonates will dissolve in dilute
acids. You might first try soaking the sieve in vinegar. If this does not
work, then a weak solution of a stronger acid such as hydrochloric (HCl)
may work, say a 1 to 5% solution. Some toilet bowl cleaners are 10% HCl.
***CAUTION!*** This may cause damage to the wires of your sieve,
especially if they are made of brass or bronze. I would test first with a
piece of brass or bronze sieve wire and a bit of "malachite" placed in a
glass dish with a weak solution of HCl.
I hope this is of some help.
Logan Oplinger
Another Tropical Island
Jim Pendley on fri 15 apr 05
I have used a lot of malachite compunds in
microbiology
stains and all of them were water soluble. The color
of malachite is so strong, that a lot of rinsing has
to occur to clear it. If some of the granules are
larger, it takes a while to dissolve them. Never tried
it with a sieve as mine came already finely
granulated.
Also sometimes a 10% alcohol solution is used. I seem
to remember most of mine were the oxalate compound.
Jim
--- Logan Oplinger
wrote:
> On Tue, 12 Apr 2005 09:20:19 -0400, John Kudlacek
> wrote:
>
> >Anyone,
> > ..... Now, about sieves: I recently screened some
> malochite through a 60
> mesh
> >sieve. Some of the malochite remains imbeded in
> the screen. Anyone know
> >a way of removing these particles without damage to
> the screeen? I used
> >the sticky side of duct tape and removed the
> majority of it but still some
> >remains.
> >Thanks.
> >John Kudlacek
> >Topeka
> >
>
>
> Hello John,
>
> As Bruce has said, a good stiff scrub brush works
> well. This works best by
> using the brush on the back side of the sieve. Once
> in a while though I
> have had problems with using just a scrub brush.
> Another method is to turn
> the dry sieve upside down on a table, and with some
> force (not enough to
> damage the frame), hit opposite sides of the sieve
> frame simultaneously
> with the flat of both hands. After each hit, rotate
> the frame a bit and
> hit again. About 10 to 15 times will remove most
> grains that can be
> removed this way.
>
> Occasionally, if I want to remove any trapped grains
> of material that may
> cause discoloration of a clay or glaze, I have
> resorted to a method that is
> highly discouraged by those who use sieves for doing
> particle size
> analysis. For sieves having an opening of 60 mesh
> or larger, and with the
> aid of a magnifying glass, I have used a fine sewing
> needle with gentle
> pressure on each grain from the back side of the
> sieve. This will take
> time but is effective. ***CAUTION!*** By using
> this method you do run the
> risk of deforming the sieve wires and causing the
> openings to become larger.
>
> Finally, you say the material that remains trapped
> in your sieve
> is "malochite". If you mean "molochite", this is
> calcined alumina silicate
> mineral, sometimes used as grog, which is insoluble
> in dilute acid.
>
> If, however, you do mean "malochite" or "malachite",
> this is a green copper
> mineral which is a carbonate. Most carbonates will
> dissolve in dilute
> acids. You might first try soaking the sieve in
> vinegar. If this does not
> work, then a weak solution of a stronger acid such
> as hydrochloric (HCl)
> may work, say a 1 to 5% solution. Some toilet bowl
> cleaners are 10% HCl.
> ***CAUTION!*** This may cause damage to the wires
> of your sieve,
> especially if they are made of brass or bronze. I
> would test first with a
> piece of brass or bronze sieve wire and a bit of
> "malachite" placed in a
> glass dish with a weak solution of HCl.
>
> I hope this is of some help.
>
> Logan Oplinger
> Another Tropical Island
>
>
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John Kudlacek on tue 19 apr 05
Dear Logan,
Yes, malachite is "green" and my face is "red". I did mean molochite.
I liked your suggestions except the "one at a time with the needle" and
will give it a go.
Thanks,
John from Oz
John Kudlacek on tue 19 apr 05
Hi Jim, Thanks for your advise but I erred and notice now that I
said "molochite" in one sentence and "malachite" in the other. The
material was actually molochite. Good thing I am not a pharmacist.
John
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