Glaze with barium carbonate

[Juliana borges]

Can Barium carbonate be used in glazes for dishes? 

[Min]

It's definitely not something I would use. Is it for the colour response of colouring oxides you want to use it or to create a matte or just because it's part of a recipe you use? Strontium carbonate can be subbed at 75% of the amount of barium carbonate that is called for in the recipe but if it's the main flux in the glaze it won't have the same colour response,  "barium blues" for example won't look the same. Much of the danger of barium carbonate is to the potter making the glaze but any surface used for food surfaces should be tested for leaching. If the glaze isn't a fully melted stable glass there will be barium leaching. Good article on barium safety here. 

Welcome to the forum 

[liambesaw]

I've read that the main problem with barium is that the desirable effects it causes also cause it to be nondurable.  So a glaze that doesn't work with a strontium substitute will not be durable with barium.

[Marcia Selsor]

I wouldn't use it on a surface where it contacts food. Bigger problem is that raw  barium can enter the potters' body through skin contact. Air born dust is also BAD. Always use gloves and masks when working around barium.

Marcia

[CactusPots]

Have you ever heard of a documented case of barium  poisoning?  The only one I've ever heard of was a case of mistaking barium for for baking powder.  I'm not saying reasonable precautions aren't advisable,   I would like to see the data on raw barium entering the body through skin contact.  Doesn't seem like we hear much about death by potter's studio.

[Marcia Selsor]

It isn't something mentioned in everyday conversation. You need to be proactive in researching what you are using. You can check individual materials MSDS sheets. Check some of the Black clays for example for their manganese content. When I was teaching at the university, we had to eliminate Barium from the studio back in the 80s.

https://www.hazwastehelp.org/ArtHazards/ceramics.aspx

https://emergency.cdc.gov/agent/barium/casedef.asp

We do know that Hans Coper and Dave Shaner were both  poisoned by Manganese in their work and eventually died from it.

. It is good to be aware of your materials. Heavy metals accumulate in the body and over time can take their toll.

 

Marcia

[CactusPots]

The case description of barium specifically states ingestion.  No mention of skin absorption.  Also, the description of toxic amounts is missing.  I suspect it's a pretty good amount.

I live in California where every single thing has a warning label.   For me it's the old Boy Who Cried Wolf.  I handle barium just like any other glaze ingredient.

Your mileage may vary.

[liambesaw]

1 hour ago, CactusPots said:

The case description of barium specifically states ingestion.  No mention of skin absorption.  Also, the description of toxic amounts is missing.  I suspect it's a pretty good amount.

I live in California where every single thing has a warning label.   For me it's the old Boy Who Cried Wolf.  I handle barium just like any other glaze ingredient.

Your mileage may vary.

According to the sds of both barium carbonate and barium oxide it shows as a skin irritant as well.  They're also both water soluble and are dangerous to aquatic life, so water contamination is a risk.

Important to read the SDS of all of the minerals we use so we can gauge the risks we are exposed to as potters, and the risk we expose others to as consumers as well. 

I'd say the biggest risk involved with barium for the Potter is inhalation of vapor during firing and inhalation of the raw material, this is a direct pathway to our internal organs.  The occupational safety limit for airborne barium oxide is under half a milligram per cubic meter which is an extremely tiny amount, wear your respirator!

[Min]

Remember that barium carbonate once ingested and subject to the hydrochloric acid in our stomachs converts to barium chloride which is definitely known to be toxic.  Barium carb is known to precipitate out of a glaze matrix if the glaze isn't well balanced therefore can be subject to leaching. It's not a case of an acute poisoning (like the deaths attributed to it in this article) but a situation where it could be a chronic issue. 

 

[Marcia Selsor]

Liam said 

"I'd say the biggest risk involved with barium for the Potter is inhalation of vapor during firing and inhalation of the raw material, this is a direct pathway to our internal organs.  The occupational safety limit for airborne barium oxide is under half a milligram per cubic meter which is an extremely tiny amount, wear your respirator!"

Dave Shaner attributes his decline to the fumes from his kiln. Hans Coper who also used manganese extensively, declined so much towards the end that he needed a rope alone the walk to his studio. Nervous system deterioration.

Marcia

 

[Ciara]

Hi, I have a related question.  I'm an amateur and recently made some glazes using Barium Carbonate and used it to glaze some bowls, however I've since learned that it isn't safe to use for dinnerware items.  I'll be steering clear of it in future but is there any way to rescue the pieces that I have glazed in it.  Could I glaze them again with a dinnerware safe clear glaze?

Also there are mentions above of the dangers of Manganese, is this only when glazing or is it also unsafe to use in glazes intended for food vessels?

Thanks in advance

Ciara 

[liambesaw]

3 minutes ago, Ciara said:

Hi, I have a related question.  I'm an amateur and recently made some glazes using Barium Carbonate and used it to glaze some bowls, however I've since learned that it isn't safe to use for dinnerware items.  I'll be steering clear of it in future but is there any way to rescue the pieces that I have glazed in it.  Could I glaze them again with a dinnerware safe clear glaze?

Also there are mentions above of the dangers of Manganese, is this only when glazing or is it also unsafe to use in glazes intended for food vessels?

Thanks in advance

Ciara 

I leave the manganese for non food surfaces, but the main risk with manganese is to the potter, not the user.

[Callie Beller Diesel]

There's not really any guaranteed way to rescue a pot that's been glazed with something that isn't ideal for food use. Glaze doesn't act like an isolated coating like paint: when you refire a piece, everything melts again, so the cover glaze is going to interact and react with whatever's underneath it. This could make the glaze more durable, or it might unbalance the fluxes so it's actually even more soluble. You'd have to send the piece to a lab for testing, so you could see exactly what does or doesn't leach out to know for sure. If you're in the beginning stages of your clay journey, a hammer is usually a better bet. Your next pot will be better for learning, I promise.

All that said, I will say that I think you're not likely to be acutely poisoned by your lone barium glazed bowl, and barium is not fat soluble. I wouldn't sell anything with a barium matte or use it myself on the daily as they're not that durable and they mark and stain, but if you need a key bowl, I'm sure it's fine.  As Liam mentioned, the danger is in the mixing and firing of the glazes. Good hygiene (gloves, respirator, ventilation, no food and drinks in the glaze room, no working next to firing kilns, etc) is always a good idea.

[Ciara]

45 minutes ago, Callie Beller Diesel said:

There's not really any guaranteed way to rescue a pot that's been glazed with something that isn't ideal for food use. Glaze doesn't act like an isolated coating like paint: when you refire a piece, everything melts again, so the cover glaze is going to interact and react with whatever's underneath it. This could make the glaze more durable, or it might unbalance the fluxes so it's actually even more soluble. You'd have to send the piece to a lab for testing, so you could see exactly what does or doesn't leach out to know for sure. If you're in the beginning stages of your clay journey, a hammer is usually a better bet. Your next pot will be better for learning, I promise.

All that said, I will say that I think you're not likely to be acutely poisoned by your lone barium glazed bowl, and barium is not fat soluble. I wouldn't sell anything with a barium matte or use it myself on the daily as they're not that durable and they mark and stain, but if you need a key bowl, I'm sure it's fine.  As Liam mentioned, the danger is in the mixing and firing of the glazes. Good hygiene (gloves, respirator, ventilation, no food and drinks in the glaze room, no working next to firing kilns, etc) is always a good idea.

Thank you for the speedy replies.  I feared that might be the case!