L. P. Skeen on sat 6 jan 07
Greetings gurus. :)
I am cleaning the heck outta my studio this weekend, and came across
some colorants I didn't know I had.
First one is cobalt carbonate. That stuff is usually purple, but this
has been around so long it's changed to a lavender-gray color. Will
that make any difference in the coloring power of the chemical?>
Next, I found something called Solomon RIO. It's really bright colored,
as opposed to "regular" rio, which is dark. Can it be used the same way?
Next, I have a bottle containing what the bottle SAYS is hematite. It
looks like RIO to me. It was brought here by a grad student for use in
a water filter experiment he was doing (I mixed the clay and threw the
filters for him).
Finally, I have another bottle from same grad student, and it says
Magnetite (Fe(x) O(x)). Looks like BIO to me.
Also discovered: about 10lbs volcanic ash, 10lbs Gillespie Borate and
5lb Laguna Borate from way back when they first started making the GB
subs. I think I was going to try Mel's ash/G borate blend glaze and
didn't get around to it. Did we decide if that was a stable glaze at ^6?
Thanks y'all.
L
Snail Scott on sun 7 jan 07
At 06:30 PM 1/6/2007 -0500, you wrote:
>Greetings gurus. :)
>
>I am cleaning the heck outta my studio this weekend, and came across
>some colorants I didn't know I had.
>
>First one is cobalt carbonate. That stuff is usually purple, but this
>has been around so long it's changed to a lavender-gray color. Will
>that make any difference in the coloring power of the chemical?
I'm accustomed to bubblegum-pink
cobalt carb, but my last batch was
orchid-purple and changed to umber-brown
as it sat. Apparently adulterated with
something that wasn't cobalt, but
it wasn't enough that I could see a
difference with my recipes.
>Next, I found something called Solomon RIO. It's really bright colored,
>as opposed to "regular" rio, which is dark. Can it be used the same way?
The brighter colors of RIO are
worth saving for washes and for
RIO-only colored glazes, where
the color difference is notable
and special. Normally the bright
stuff costs more, and is sold as
'glaze-grade' RIO or some such name.
>Next, I have a bottle containing what the bottle SAYS is hematite. It
>looks like RIO to me...
>Finally, I have another bottle from same grad student, and it says
>Magnetite (Fe(x) O(x)). Looks like BIO to me.
Hematite and magnetite are ores which
are high in iron. They will vary a
little, but basically they will act
like iron.
-Snail
Bonnie Hellman on sun 7 jan 07
Hi Cindy,
I have to say that your experience with US Pigment has not been my
experience. I have paid more for cobalt and gotten the same quality as I
received from US Pigment. The cobalt I bought from them has not changed
color in the dry form either.
What I can't say is that cobalt from 20 or 30 years ago was either more
intense or weaker. I tend to (almost) use up old cobalt before buying more.
I have also had good experiences with their commercial Chinese stains, too.
Bonnie D. Hellman
Ouray, Colorado 81427
----- Original Message -----
From: "Cindy Gatto"
To:
Sent: Sunday, January 07, 2007 12:13 PM
Subject: Re: colorants for glaze (Ron/John pls have a look)
> Hi Lisa,
> Several years ago I purchased some cobalt carb from US Pigments. They sell
> chemicals at a discount.You just have to buy a bulk weight. I got 10 lbs
> of the
> cobalt at half the market price. When it came it was a really light
> lavender grey color It was very weak about a 2 to 1 ratio So the half
> price was
> moot because you have to use twice as much. I don't know if this is what
> you
> have but I did have cobalt that had been stored for 20 yrs and another
> batch
> that had been stored for 30 yrs and neither of those had changed color
>
> Cindy Gatto & Mark Petrin
> The Mudpit
> 228 Manhattan Ave
> Brooklyn, NY 11206
> 718-218-9424
> _www.mudpitnyc.com_ (http://www.mudpitnyc.com/)
> mudpitnyc@aol.com
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
L. P. Skeen on sun 7 jan 07
Thanks Snail for all the information. Think I may do some testing w/
those two bottles of hematite/magnetite and see what I get. :)
L
Snail Scott wrote:
> Hematite and magnetite are ores which
> are high in iron. They will vary a
> little, but basically they will act
> like iron.
>
> -Snail
>
>
Cindy Gatto on sun 7 jan 07
Hi Lisa,
Several years ago I purchased some cobalt carb from US Pigments. They sell
chemicals at a discount.You just have to buy a bulk weight. I got 10 lbs of the
cobalt at half the market price. When it came it was a really light
lavender grey color It was very weak about a 2 to 1 ratio So the half price was
moot because you have to use twice as much. I don't know if this is what you
have but I did have cobalt that had been stored for 20 yrs and another batch
that had been stored for 30 yrs and neither of those had changed color
Cindy Gatto & Mark Petrin
The Mudpit
228 Manhattan Ave
Brooklyn, NY 11206
718-218-9424
_www.mudpitnyc.com_ (http://www.mudpitnyc.com/)
mudpitnyc@aol.com
Ron Roy on sun 7 jan 07
Hi Lisa,
I don't have the kind of experience to answer this for sure - except that
the cobalt will be fine.
The way to find out about the irons is to test them in a known glaze - that
has 3 or 4 % of iron in it.
The Gillespie Borate is the closest thing to the old GB by the way - we
would all like to know if it works well as a straight sub.
Post the GB/ash glaze and I will take a look but there is no standard
analysis for ash so how can it be done. Add 5% copper carb and 6 % Rutile
and send it off to a lab and have it tested for copper leaching.
RR
>I am cleaning the heck outta my studio this weekend, and came across
>some colorants I didn't know I had.
>
>First one is cobalt carbonate. That stuff is usually purple, but this
>has been around so long it's changed to a lavender-gray color. Will
>that make any difference in the coloring power of the chemical?>
>
>Next, I found something called Solomon RIO. It's really bright colored,
>as opposed to "regular" rio, which is dark. Can it be used the same way?
>
>Next, I have a bottle containing what the bottle SAYS is hematite. It
>looks like RIO to me. It was brought here by a grad student for use in
>a water filter experiment he was doing (I mixed the clay and threw the
>filters for him).
>
>Finally, I have another bottle from same grad student, and it says
>Magnetite (Fe(x) O(x)). Looks like BIO to me.
>
>Also discovered: about 10lbs volcanic ash, 10lbs Gillespie Borate and
>5lb Laguna Borate from way back when they first started making the GB
>subs. I think I was going to try Mel's ash/G borate blend glaze and
>didn't get around to it. Did we decide if that was a stable glaze at ^6?
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
sacredclay on sun 7 jan 07
-Not that I am in the expert in the field of Ron, John, and many
others, so I'll just put in my two cents worth based on my experiece.
I've come across cobalt carbonates that are a different hues and the
explanation that I was told is that it's mined in a different area.
However, in your case, you stated that it has changed colors. My hunch
is that it is still ok. I've heard of Solomon RIO and I'd probably use
it in the same way as a regular RIO. This is based on my doing the same
with Spanish RIO, which is a little brighter red, or more intense.I've
got alot of chemicals that has had the labels fall of so I've got to
guess what they are. I've got one with what looks like BIO but water
has leaked into it. Still, I'll try it and see what happens. You should
do the same with yours. Experiment with it and have fun.As for Laguna
Borate, when I first used it, it sucked big time. It was too heavy and
tended to settled out in the buckets and also wasn't a faithful enough
to reproduced the glazes I needed.My students couldn't understand that
and just nodded their heads wisely, obviously thinking,"She knows
diddle-squat Kathryn in NC
Snail Scott on mon 8 jan 07
At 04:47 AM 1/8/2007 -0000, you wrote:
>Snail, Once I used red copper Oxide as an iron wash. Had a hard time
>getting the chemicals to disolved in the water. It seemed to repel
>the liguid and was still powdery.. Any reason why?
The chemistry of the effect exceeds
my expertise, but it is totally typical
of red copper oxide. Some folks use
dish detergent (just a little!) to
break the surface tension of the water
and allow it to be mixed into suspension.
Dish detergent contains 'wetting
agents' which allow this to happen.
One can purchase wetting agents in
pure form, but they are not as easy
to find (especially in non-industrial
quantities), they ain't too cheap,
AND their high concentration means
precision dilution is required. Dish
soap makes the glaze foamy if mixed
enthusiastically, but it's a cheap
and easy source of a wetting agent.
-Snail
claystevslat on mon 8 jan 07
Magnetite is an isometric crystalline form of iron oxide. (Crystals
shaped like pyrite.)
Hematite is a trigonal crystal.
Whether this makes a difference in a glaze will depend on many
different things, including the fineness of the mineral and the
concentration in the glaze, as well as the glaze chemistry. (It
is one of my theories that it will make a greater difference in
glazes in which the concentration of the iron compound is greater
than 8% of the amount 'above the line.' This theory is based on far
too little experimentation to have any claim to validity, and I will
abandon it in a flash if anyone has any evidence indicating the
contrary.)
I suspect from the materials you mention that you caught hold of the
stock of someone who was researching the effect of different
crystalline formation in iron compounds on final glaze results -- it's
all well and good to say that iron is iron and that's that, but there
are readily visible differences between the different sources of iron,
and a bag of "red iron oxide" is rather vaguely specified. Didn't
someone recently do some tests with RIO from a rusty Chevy pickup
truck?
-- Steve S
--- In clayart@yahoogroups.com, you wrote:
>Next, I have a bottle containing what the bottle SAYS is hematite. It
>looks like RIO to me...
>Finally, I have another bottle from same grad student, and it says
>Magnetite (Fe(x) O(x)). Looks like BIO to me.
sacredclay on mon 8 jan 07
Snail, Once I used red copper Oxide as an iron wash. Had a hard time
getting the chemicals to disolved in the water. It seemed to repel
the liguid and was still powdery.. Any reason why? Kathryn in NC---
In clayart@yahoogroups.com, Snail Scott wrote:
>
> At 06:30 PM 1/6/2007 -0500, you wrote:
> >Greetings gurus. :)
> >
> >I am cleaning the heck outta my studio this weekend, and came
across
> >some colorants I didn't know I had.
> >
> >First one is cobalt carbonate. That stuff is usually purple, but
this
> >has been around so long it's changed to a lavender-gray color.
Will
> >that make any difference in the coloring power of the chemical?
>
>
> I'm accustomed to bubblegum-pink
> cobalt carb, but my last batch was
> orchid-purple and changed to umber-brown
> as it sat. Apparently adulterated with
> something that wasn't cobalt, but
> it wasn't enough that I could see a
> difference with my recipes.
>
>
> >Next, I found something called Solomon RIO. It's really bright
colored,
> >as opposed to "regular" rio, which is dark. Can it be used the
same way?
>
> The brighter colors of RIO are
> worth saving for washes and for
> RIO-only colored glazes, where
> the color difference is notable
> and special. Normally the bright
> stuff costs more, and is sold as
> 'glaze-grade' RIO or some such name.
>
>
> >Next, I have a bottle containing what the bottle SAYS is
hematite. It
> >looks like RIO to me...
> >Finally, I have another bottle from same grad student, and it says
> >Magnetite (Fe(x) O(x)). Looks like BIO to me.
>
>
> Hematite and magnetite are ores which
> are high in iron. They will vary a
> little, but basically they will act
> like iron.
>
> -Snail
>
>
______________________________________________________________________
________
> Send postings to clayart@...
>
> You may look at the archives for the list or change your
subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@...
>
Timothy Joko-Veltman on mon 8 jan 07
On 1/8/07, sacredclay wrote:
> Snail, Once I used red copper Oxide as an iron wash. Had a hard time
> getting the chemicals to disolved in the water. It seemed to repel
> the liguid and was still powdery.. Any reason why? Kathryn in NC---
I'm not Snail, but can answer this ... Red Copper Oxide is coated to
prevent further oxidation. This coating is also water resistant, so it
won't suspend well in a glaze. Adding a couple drops of dish
detergent to the glaze water or soaking it in alcohol should resolve
the problem.
Cheers,
Tim
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