Using Cobalt Oxide as a Clay Colorant

[Grace W]

Hi there! New in town but not to pottery. 

 

I am wondering if anyone has ever used cobalt oxide as a clay colorant? I love the look and have been experimenting with it for a few years now but I am wondering about the safety of throwing with it.

I do a .5 - 1% ratio with a white clay body and it creates really beautiful results but wondering if I should be wearing gloves when wedging and throwing (wearing gloves while throwing seems terrible?)

I would be open to using a stain or something less caustic if I could get similar results, but I inherited some materials so have just been using what I have. 

 

Thanks! 

Edited August 21 by GraceKW

[PeterH]

34 minutes ago, Grace W said:

but wondering if I should be wearing gloves when wedging and throwing (wearing gloves while throwing seems terrible?)

Hope it doesn't come to that, but related thread.

 

[Callie Beller Diesel]

If you’re concerned, using a stain going forward might be a good idea. Sure wouldn’t hurt, anyways. The cobalt can be used in glazes and is unlikely to go to waste. 

[Mark C.]

There is a lot of folks doing this just google it up

[Grace W]

1 hour ago, Mark C. said:

There is a lot of folks doing this just google it up

Helpful! I can only find information on adding it to slips and glazes really, which is why I am asking here. 

[Min]

Cobalt is a transition (heavy) metal. Adding it to a claybody, working with with bare hands,  trimming plus dealing with the dry scraps are all going to expose you to it. There are numerous articles on cobalt toxicity, many are dealing with cobalt in it's metallic form. As potters we are dealing with the oxide and carbonate for the most part, unless you use cobalt salts and that's a whole other issue. Route of entry into the body can be through skin, only very very slighly, broken skin, much higher rates of absorpion, ingestion, not likely, and inhalation. I'm one of those people with skin sensitivities, if you can avoid even getting that from cobalt exposure it would be a plus.

We also have to consider total body burden and the "doseage" exposed to. Given there are alternatives that are known to be safer, ie stains, I would use those instead.

I found conflicting articles on the toxicity as it pertains to how we are exposed to it. The European Chemical Agency, dated Dec 2023, has this to say about it:

https://echa.europa.eu/substance-information/-/substanceinfo/100.013.777

[PeterH]

2 hours ago, Grace W said:

Helpful! I can only find information on adding it to slips and glazes really, which is why I am asking here. 

You might start with:

HOW TO COLOR CLAY WITH MASON STAINS
http://www.ccpottery.com/colored-clay-lessons--chris/how-to-color-clay-with.html

[PeterH]

11 hours ago, Grace W said:

Helpful! I can only find information on adding it to slips and glazes really, which is why I am asking here. 

A useful search term is
body stain
... which tries to restrict the search to stains that are specifically recommended for use in clay bodies

You can tighten the search by adding the name of a major stain manufacturer, such as
body stain Mason

If you want to restrict the search to this site try
community.ceramicartsdaily.org body stain

Better yet, if you are using google try
site:community.ceramicartsdaily.org body stain
... which is how I found a thread that mentioned Chris Campbell's work. Which I then searched for with
Chris Campbell body stain

Be aware that some stains have unfortunate colour reactions with some glazes (and possibly some bodies).

PS Bold used for emphasis only.

Edited August 22 by PeterH

[Grace W]

16 hours ago, Min said:

Cobalt is a transition (heavy) metal. Adding it to a claybody, working with with bare hands,  trimming plus dealing with the dry scraps are all going to expose you to it. There are numerous articles on cobalt toxicity, many are dealing with cobalt in it's metallic form. As potters we are dealing with the oxide and carbonate for the most part, unless you use cobalt salts and that's a whole other issue. Route of entry into the body can be through skin, only very very slighly, broken skin, much higher rates of absorpion, ingestion, not likely, and inhalation. I'm one of those people with skin sensitivities, if you can avoid even getting that from cobalt exposure it would be a plus.

We also have to consider total body burden and the "doseage" exposed to. Given there are alternatives that are known to be safer, ie stains, I would use those instead.

I found conflicting articles on the toxicity as it pertains to how we are exposed to it. The European Chemical Agency, dated Dec 2023, has this to say about it:

https://echa.europa.eu/substance-information/-/substanceinfo/100.013.777

Thank you so much! 

[Grace W]

20 hours ago, PeterH said:

Hope it doesn't come to that, but related thread.

 

I took a class with a woman who threw in gloves, I have tried it before when I have a cut on my hand and it's definitely tricky but I can see getting used to it if I needed to. 

[Mark C.]

There was woman for years here that does colored claty workshops-Her Name is Chris Campbell if I recall -look up her posts on this subject say 6-10 years ago.

[PeterH]

52 minutes ago, Mark C. said:

There was woman for years here that does colored claty workshops-Her Name is Chris Campbell if I recall -look up her posts on this subject say 6-10 years ago.

Is there anything specific you're thinking of, we've already referenced her colored clay web page.
http://www.ccpottery.com/colored-clay-lessons--chris/how-to-color-clay-with.html

@Grace W The search function on this site only examines "active" threads. To search the whole site for contributions by Chris Campbell ...
for google
site:community.ceramicartsdaily.org Chris Campbell
for other search engines
community.ceramicartsdaily.org Chris Campbell

PS Note that Chris just happened to register here as Chris Campbell, most people use shortened forms or pseudonyms.

[Mark C.]

Thanks Peter for posting this.Its all been covered well here in the past as you noted

[Babs]

On 8/22/2024 at 5:50 AM, Grace W said:

Helpful! I can only find information on adding it to slips and glazes really, which is why I am asking here. 

Google neriage work,

Chris Campbell coloured clays

http://www.ccpottery.com/

Only consideration that I can see is $$$ when you get hooked on the cobalt and need to buy some more... 

A body stain would be a lot less expensive.