[Clayart] cobalt free black mason stain

[jonathan byler]

Can anyone tell me the benefits (or lack thereof) from using "cobalt free" black mason stain 6666 instead of the standard 6600 black? I thought these were all “encapsulated” pigments, which rendered them safer than using oxides on their own.

-jb

[Paul Lewing]

On Nov 30, 2016, at 11:28 AM, jonathan byler <jeby...@gmail.com> wrote:

Can anyone tell me the benefits (or lack thereof) from using "cobalt free" black mason stain 6666 instead of the standard 6600 black? I thought these were all “encapsulated” pigments, which rendered them safer than using oxides on their own.

Only the cadmium stains are encapsulated. I’m not sure whether oxides derived from a stain are any safer, or indeed any different, from raw oxides in their ability to stay in a glaze. You may not notice any difference among the various black stains if you use them full strength to make a real black, but you will notice a huge difference at lower concentrations. I use a lot of the chrome-free black stain at about 5-6% to get a lovely blue-grey. I would expect the cobalt free stain at that concentration to give me a completely different grey.

Paul Lewing
www.paullewingtile.com <http://www.paullewingtile.com/>
www.paullewingart.com <http://www.paullewingart.com/>
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[Joan Klotz]

I don't think any of the Mason black stains are
encapsulated. I do a lot of surface decoration
on my work and frequently have problems with the
cobalt containing blacks when they are used on
vertical surfaces and then covered with a
transparent glaze with any fluidity. Cobalt (or
something blue) is released resulting in a blue
shadow below the black lines or shapes which I
personally do not like. I am planning to try the
6666 stain to see if that solves the problem.

At 11:28 AM 11/30/2016, jonathan byler wrote:
>Can anyone tell me the benefits (or lack
>thereof) from using "cobalt free" black mason
>stain 6666 instead of the standard 6600
>black? I thought these were all

>“encapsulated†pigments, which rendered them

[Robert Harris]

In addition to Paul's good points about greys, a lot of people use the
black mason stains for drawing black lines etc. With certain glazes the
cobalt containing mason stains give blue halos. This can look nice, but
other people simply don't want that blue leaching effect. The non-cobalt
mason stains such as 6666 are excellent for this purpose.

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[jonathan byler]

If they are not encapsulated, is there any advantage to using them over mixing up your own batch of black oxides instead? I thought that was the whole charm of mason stains, encapsulated and more consistent and stable…

[Vince Pitelka]

We need to clarify the terminology here. All fritted stains are encapsulated, but only the touchy reds and oranges that contain cadmium and other dangerous chemicals are zirconium-encapsulated (in an ultra-high-temperature zirconium glass). Those stains remain as colored inclusions suspended in the glaze without ever dissolving into the melt, and thus the dangerous chemicals remain safely encapsulated. All other fritted stains we use in studio ceramics are encapsulated in silica glass which does dissolve into the melt, depending on firing temperature. Essentially a fritted stain like a Mason stain is just a very intensely-colored glass ground back to a powder. The primary advantages are broad color range, non-toxic in skin contact, insoluble in water, and stable and reliable in use. Mason and other stain manufacturers can accomplish all sorts of things mixing chemicals in industrial conditions that we cannot do in our studios. Regarding black, I can get a much better black in a slip or colored clay with Mason stains than I can with oxides. If I want blues or greens in a slip, I use cobalt carb or oxide, chrome oxide, and copper carb, but if I want a good black slip, I use Mason stain, either the 6600 Best Black, or the cobalt-free black.
- Vince

Vince Pitelka
Appalachian Center for Craft
Tennessee Tech University
vpit...@dtccom.net
https://sites.tntech.edu/wpitelka/

[Robert Harris]

I don't know the specifics of the blacks, but a number of the blues, for
example, are zirconium/vanadium based. These produce a very different shade
from the usual cobalt silicates that we get by adding cobalt to a
glass.These colours (and others) are produced at about Cone 14+ from my
recollection, which of course doesn't happen in a normal gas firing. I
don't think even Mel and his "hotter is better" buddies fire that high!

Think of them more like frits, some of them you could get by adding the raw
materials, but are better mixed when in a frit, others would simply not be
available using raw materials (for example strontium is an excellent low
temperature flux, but since strontium carbonate doesn't decompose until
about 2000C it must be used in a frit to take advantage of its low
temerature fluxing properties).

The only encapsulated stains are those containing highly toxic metals such
as cadmium and selenium which are used to make bright reds and yellows.

Other mason stains use colourants such as vanadium which are toxic in the
oxide form, and have been phased out of use in most studios, but are
totally safe when in an alumino-silicate form.

Hope this makes some sense.

Robert

Of course some you could certainly get by adding the appropriate amount of
cobalt and chrome oxides together, for example. Mason have just put them
together in a generally pleasing ratio.

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[Paul Lewing]

On Dec 1, 2016, at 9:21 AM, jonathan byler <jeby...@gmail.com> wrote:

If they are not encapsulated, is there any advantage to using them over mixing up your own batch of black oxides instead? I thought that was the whole charm of mason stains, encapsulated and more consistent and stable…

Only the Cd stains are encapsulated, because they’re the only ones that are so unstable that they need that.

Commercial stains do tend to be more consistent than what you mix from raw oxides, and unless you ball mill your oxides, much finer particle size. It’s also really hard to get the subtle variety of colors that you can get with stains. Yu can get green from chrome, for instance, but you may not be able to get the 15 different shades or so of green that you can get with Cr based stains. Also, most stains are not just oxides mixed together, but also have some other process, usually heating to some degree or other. Some colors require firing to very specific temperatures. The iron reds and browns are particularly sensitive that way. The same menu of oxides make several different shades depending on how high they’re fired.

By the way, Mason is a brand name, not a kind of stain. It has nothing to do with masonry. Mason stains are the most common in the US, but there are many other companies making ceramic stains.

Paul Lewing
www.paullewingtile.com <http://www.paullewingtile.com/>
www.paullewingart.com <http://www.paullewingart.com/>

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[jonathan byler]

Thanks for the clarification vince. this is what I was assuming, but wasn’t 100% sure about. nice for making black clay and slip!

[jonathan byler]

> On Dec 1, 2016, at 5:36 PM, Robert Harris <robert...@gmail.com> wrote:
>
> (for example strontium is an excellent low
> temperature flux, but since strontium carbonate doesn't decompose until
> about 2000C it must be used in a frit to take advantage of its low
> temerature fluxing properties).

If strontium carbonate doesn’t decompose and work as a flux until 2000C, why is it recommended as a sub for barium carbonate in many glaze recipes?

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[Robert Harris]

Sorry I mistyped (most work I do is in C and I had "auto-finger" disease!).
Strontium Carbonate doesn't de-compose until 2000F (1100C). So it's fine
for cone 10 glazes as a sub for Barium, but it won't work as a low
temperature flux unless it's in a frit.

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[Ric Swenson]

Ron Mason and his daughter were good friends...had him talk at Am Cer Society..Design Division when I was chair in 1984-6....used his stains a lot...Black was a favorite.

ric

________________________________
From: Clayart <clayart...@lists.clayartworld.com> on behalf of jonathan byler <jeby...@gmail.com>
Sent: Saturday, December 3, 2016 1:10 AM

To: Clayart international pottery discussion forum

Subject: Re: [Clayart] cobalt free black mason stain

Thanks for the clarification vince. this is what I was assuming, but wasn't 100% sure about. nice for making black clay and slip!

> On Dec 1, 2016, at 4:38 PM, Vince Pitelka <vpit...@dtccom.net> wrote:
>
> We need to clarify the terminology here. All fritted stains are encapsulated, but only the touchy reds and oranges that contain cadmium and other dangerous chemicals are zirconium-encapsulated (in an ultra-high-temperature zirconium glass). Those stains remain as colored inclusions suspended in the glaze without ever dissolving into the melt, and thus the dangerous chemicals remain safely encapsulated. All other fritted stains we use in studio ceramics are encapsulated in silica glass which does dissolve into the melt, depending on firing temperature. Essentially a fritted stain like a Mason stain is just a very intensely-colored glass ground back to a powder. The primary advantages are broad color range, non-toxic in skin contact, insoluble in water, and stable and reliable in use. Mason and other stain manufacturers can accomplish all sorts of things mixing chemicals in industrial conditions that we cannot do in our studios. Regarding black, I can get a much better black in a slip or colored clay with Mason stains than I can with oxides. If I want blues or greens in a slip, I use cobalt carb or oxide, chrome oxide, and copper carb, but if I want a good black slip, I use Mason stain, either the 6600 Best Black, or the cobalt-free black.
> - Vince
>
> Vince Pitelka
> Appalachian Center for Craft
> Tennessee Tech University
> vpit...@dtccom.net
> https://sites.tntech.edu/wpitelka/

Vince Pitelka - Tennessee Technological University ...<https://sites.tntech.edu/wpitelka/>
sites.tntech.edu
I have been a studio clay artist for 45 years, teaching clay at the university level since 1986, the last 22 years in Tennessee Technological University's School of ...

>
> -----Original Message-----
> From: Clayart [mailto:clayart...@lists.clayartworld.com] On Behalf Of jonathan byler
> Sent: Thursday, December 1, 2016 11:22 AM
> To: Clayart international pottery discussion forum <cla...@lists.clayartworld.com>
> Subject: Re: [Clayart] cobalt free black mason stain
>

> If they are not encapsulated, is there any advantage to using them over mixing up your own batch of black oxides instead? I thought that was the whole charm of mason stains, encapsulated and more consistent and stable...

>
>
>> On Nov 30, 2016, at 11:37 PM, Joan Klotz <Veni...@ca.rr.com> wrote:
>>
>> I don't think any of the Mason black stains are encapsulated. I do a lot of surface decoration on my work and frequently have problems with the cobalt containing blacks when they are used on vertical surfaces and then covered with a transparent glaze with any fluidity. Cobalt (or something blue) is released resulting in a blue shadow below the black lines or shapes which I personally do not like. I am planning to try the 6666 stain to see if that solves the problem.
>>
>> At 11:28 AM 11/30/2016, jonathan byler wrote:

>>> Can anyone tell me the benefits (or lack thereof) from using "cobalt free" black mason stain 6666 instead of the standard 6600 black? I thought these were all âEURoeencapsulatedâEUR pigments, which rendered them safer than using oxides on their own. -jb
>>
>>
>
>
>
>

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