Jump to content
jafa5

Lithium replacement

Recommended Posts

I'm using Woody Hughes base glaze (below) which has 4% lithium carbonate (from CM Guide to Materials).  i'd like to replace the lithium with something that's food safe, or safer but retain similar qualities to the glaze.  The glaze turns out amazing in the gas kiln, especially the copper variant.   Although i'm not sure about the copper for food safety either so i'm keeping that on the outside of sake cups.  Any feed back on copper use would be appreciated.

New potter of 6 months and still learning, so if this sounds like a newbie question, there's the reason.  I understand that if the glaze is stable, lithium should be food safe at 4% but i'd like to remove it to be sure. My firings are not consistent yet as i'm still learning the kilns hot cold spots.  Hopefully any feedback might give me a better understanding of what lithium adds and what a counterpart would add.  Digital fire is an amazing resource but i'm new to chemistry so hard to follow or understand the implications / effects.  Another 10 years I'll be able to answer some questions in return :) hopefully practical applications will bolster my progress!

The glaze characters I like are that it doesn't run, the copper is beautifully transparent and highlights the clay body plus it  doesn't crackle even with a fast cool down.

Faro fritter 3124 30

Gerstly borate 26

Nepheline synite 20

Kaolin 10

Silica 10

Lithium carbonate 4

 

Addition - low firing to 1050 degree c

Any adevice would be greatly appreciated.

Cheers,

Liam

 

Edited by jafa5

Share this post


Link to post
Share on other sites

Awesome thanks Marcia! 

I didn't see that, checked DF before I posted this too. 

The video is replacing lithium carbonate with lithium frit, so only replaces lithium with lithium.  I was really after a less toxic  material, maybe another alkali earth?  

Maybe i'lol just omit it from the recipe and see how that turns out.  What's the worst that can happen :)

Edited by jafa5

Share this post


Link to post
Share on other sites
1 hour ago, jafa5 said:

I understand that if the glaze is stable, lithium should be food safe at 4% but i'd like to remove it to be sure.

For a glaze to be stable one of the things that is super important is to have enough of both silica and alumina in the formula. There are "limits" from various sources that show the range of minimum levels of oxides. I ran your glaze through Insight and used the limits from Green & Cooper for a cone 10 glaze. In the chart below your recipe is in the first column (it's a formula not a recipe so it shows your recipe at an oxide level), the other column shows the limits. Have a look at the silica and alumina, both under the minimum limits needed. Your boron is super high, really high boron makes for a soft glaze. I also checked it with traditional cone 8-10 limits, alumina came up at the minimum level but silica was still undersupplied. 

If there is nothing nasty to leach out of a glaze then what you would be looking at with low alumina and silica levels is how durable the glaze is for functional work. 

Re lithium carbonate versus Fusion Frit 493, using a frit to supply the lithia content works to reduce the amount of lithia crystals you will get in the raw glaze slurry but the fired glaze will contain lithia either way.

 

edit: ignore all this, made an incorrect assumption about firing temperature.

Screen Shot 2018-03-03 at 11.56.34 AM.png

Edited by Min

Share this post


Link to post
Share on other sites

Thanks Min that's really helpful, might take me a few reads to soak it all in but some very clear points thank you.  I'll 

Firing for this is cone 04 to 06 if that makes a difference.

I'll load Insight and have a play with this recipe and look to increase the Silica and alumina while reducing boron and removing lithium altogether.

That'll be a fun excercise

Share this post


Link to post
Share on other sites

Yeah, just noticed the temperature, my brain just went to cone 10 since you are gas firing, my bad. Thought you meant firing down to 1050C Recipe didn't make sense for a high fire glaze.

This is the glaze with the proper limits for lowfire, looks fine as it is, no need to change anything.

 

 

 

Screen Shot 2018-03-03 at 12.45.01 PM.png

Share this post


Link to post
Share on other sites

Thanks Min :)

I have a couple of gas kilns and can go higher but starting with low fire and working my way up.  Quite fortunate to be working on a construction site for a motorway and getting access to a heap of raw materials from volcanic ash, basalt, feldspar and other rock types, most of which are going to be high fire and no doubt i'lvl have a heap of questions when I get started on that in July.

Thanks for checking the recipe and nice to know it's balanced for cone 04 to 06.  I started to look at Insight and it's going to take some time to learn that but a great looking tool.  Longer time to understand all the materials and effects of course, few years to get the basics I think.

Do you think the lithium would pose any issues for food safety?  I'd really like to use it on the inside of some of my cup forms.

Share this post


Link to post
Share on other sites

Lithium is a very active flux, I think you would notice the difference in glaze melt if you excluded it. It’s one of the alkali metal group of fluxes, (along with sodium and potassium), if you replace the lithium with more of the sodium and/or potassium you are going to increase the coefficient of expansion of the glaze and would likely run into crazing but this might work.If you use other flux(es) which are not part of the alkali metal group the colour response from the copper could be noticeably different.

The only way to know for sure if your glaze is leaching is to have a fired sample lab tested. Even then interpreting the results will be tricky as there are no drinking water regulations regarding lithium content. If you want to rule out a glaze as not being durable you can do some home testing with both a soda ash test plus the test using either vinegar or a lemon slice, but this doesn’t mean a glaze is “safe”, they just show ones that obviously are not. 

If you aren’t comfortable using lithium in your liner glaze what would seem the simplest would be to use your lithium glaze on the outside of pots as you are doing with the copper glaze and use a liner glaze recipe that doesn’t include lithium. Look for one that has roughly the same COE (or CTE) so you don’t run into dunting issues. (If you’ve installed Insight you can enter the recipe then look for the COE box to check the number for both glazes)

Share this post


Link to post
Share on other sites
On 3/3/2018 at 2:09 PM, jafa5 said:

  Although i'm not sure about the copper for food safety either so i'm keeping that on the outside of sake cups.  Any feed back on copper use would be appreciated.

I am not a chemist, but from what I have read and observed, I think the risk of copper poisoning from ceramics use is overstated. 
 

Quote

The U.S. Environmental Protection Agency's Maximum Contaminant Level (MCL) in drinking water is 1.3 milligrams per liter.[1][7] The MCL for copper is based on the expectation that a lifetime of consuming copper in water at this level is without adverse effect (gastrointestinal). The US EPA lists copper as a micronutrient and a toxin.

If you drink a liter a day of water that has up to 1.3 mg in it, and that is considered safe, any copper leaching out of a mug would be far less than this. I doubt a mug would have 1.3 mg of copper in the whole glaze application, let alone a lethal dose.  

People have been drinking vodka mules out of 100% copper cups, and we have not seen the new stories about these deadly cocktails killing consumers. That is because in order to get copper poisoning in this fashion, you would drink yourself to death long before the copper got you.

Share this post


Link to post
Share on other sites
22 hours ago, douglas said:

I am not a chemist, but from what I have read and observed, I think the risk of copper poisoning from ceramics use is overstated. 
 

If you drink a liter a day of water that has up to 1.3 mg in it, and that is considered safe, any copper leaching out of a mug would be far less than this. I doubt a mug would have 1.3 mg of copper in the whole glaze application, let alone a lethal dose.  

People have been drinking vodka mules out of 100% copper cups, and we have not seen the new stories about these deadly cocktails killing consumers. That is because in order to get copper poisoning in this fashion, you would drink yourself to death long before the copper got you.

We had a long discussion about copper some time in the last year. It's true that it takes a lot to cause a problem, although there are folks who are medically sensitive to it. If it's obviously leaching, like with a vinegar or lemon test, the glaze should be fixed.

Share this post


Link to post
Share on other sites
11 hours ago, High Bridge Pottery said:

I don't think lithium poses any toxicity issue, where did you get that from? I think having a good mix of oxides, including lithium will help retain other metals in the glass like copper or cobalt.

Will someone taking lithium for bipolar disorder get an overdose from an unbalanced or underfired glaze? I don’t think this question has a definitive yes or no answer. My understanding is the toxic and treatment levels of lithium are very close, will lithium from a leaching coffee mug  push the person into the toxic area? I don’t know. I’ve always tried to approach the safety issues with the materials we use in a manner that errs on the side of safety and common sense. Educate yourself about the materials you use, firing conditions and maintaining good studio practices while handling, applying and firing. If in doubt do some glaze testing.

In regards to the glaze discussed in this thread we also have to take into consideration the firing to cones 06 - 04. According to Dr Carty (glaze guru) from his "Overview of Glaze and Glazing Safety" general rule for glaze safety is to fire to at least cone 1. 

Share this post


Link to post
Share on other sites
8 minutes ago, Sputty said:

TBH, I think it does actually has a pretty definitive answer.

An average minimum daily dose for controlling mania in bi-polar (even in paediatrics) is going to be something like 1000mg. That's a gram. Every day. If your glaze is leaching anything that would even remotely upset those levels, then it's one heck of a (non-)glaze!

 

If you are at the maximum target dose prescribed then add supplemental lithium from a leaching mug how much are you getting?

Share this post


Link to post
Share on other sites

As Gavin Stairs says we are not in the business of supplying mineral supplements. Taken from this very common sense article. 

"Trace Elements

The thing about toxicology is that everything is toxic at some level. Hardly any exceptions. The question is what level? That is, how much? Toxicologists try to establish the 50% mortality level. With something like water, it is inconceivably high (i.e., drowning). With arsenic, small. With cyanide or strychnine, very small. Most of the elements and vitamins have moderately small levels, but some, like vitamin C, are quite large. It's rather hard to poison yourself with vitamin C. Not so hard with iron and vitamin B complex. Monona Rossol wrote about the overlap of the toxic dose and the therapeutic dose of Lithium in Ceramics Monthly. I am oversimplifying, of course. There are synergistic effects which make it highly variable in some cases.

The issue with trace elements is that we need some, but not too much. The dose in a multivitamin capsule is calculated to be enough for a daily requirement for a healthy adult, but not enough to be toxic, even if the person taking it has several times the ordinary daily intake from other sources.

The issue with pottery leaching is that we are not in the business of mineral supplements, and we cannot give a carefully controlled dose of what leaches from our pots. With some things, like silica, this is not a problem. With others, like cobalt and iron, it is rarely a problem. With things like chrome, vanadium, molybdenum, lithium, barium, perhaps aluminum, and so forth, it may be a problem. With lead and cadmium it definitely is a problem in certain cases. In some of these cases, we don't
know if it is a problem or not. The safe situation is to have durable glazes which do not leach significant amounts of anything."

Share this post


Link to post
Share on other sites

You’d probably get more lithium from eating shellfish regularly than a beloved mug or bowl.

Edit:  In all seriousness, though, something that tends to be lacking from these discussions about risk is an appreciation for the body of evidence and information that surrounds a perceived risk.

There’s a concept used in medical science called the “pyramid of evidence” that people who wish to be informed about chemical risks should acquaint themselves with.   You’ll notice that when I posted studies on topics like this, I tend to posts clouds of studies on these issues, this is to illustrate trends in these studies.  This is because, taken individually, these studies are semi-useless and confirm nothing.  Meta-analyses and systematic reviews of evidence are higher up on the pyramid and are where you should really be basing your decision making.  if they don’t exist, you find all relevant studies and compile the evidence yourself.  Unless that’s happening, it’s just cherry picked confirmation bias.

Edited by Tyler Miller

Share this post


Link to post
Share on other sites
4 hours ago, Sputty said:

an argument for formulating correctly balanced glazes when used for functional ware, not an argument for avoiding certain elements.

I don't think I was presenting an argument for avoiding lithium, I was simply trying to say that without testing an underfired or unbalanced glaze has the potential to leach lithium and without testing we don't know how much nor do we know how much is too much as there isn't even drinking water limits for this material. I use spodumene in several glazes, I don't avoid lithia.

Share this post


Link to post
Share on other sites
5 hours ago, Sputty said:

If someone can show me, properly referenced:

a ) that Lithium can in fact appreciably leach from a glaze in the first place, and under what conditions; and

b ) that the Lithium thus leached is in a bio-available form, and in quantities in any way hazardous to anyone's health

...then I'd be interested. As far as I can tell, there is not one reported instance of Lithium intoxication from ceramic sources.

I think you're looking at this backwards. It's not up to us to prove that it can leach, it's up to you to prove that it doesn't leach from your glaze. That's how the judge will approach it if you're ever in a lawsuit. From what I can find, there is no definitive answer on this because it has not been studied enough to know for sure. There are a lot of claims from both sides of the issue. Lack of evidence is not proof that a problem doesn't exist, so just like everything else, it's up to you to have your glaze tested so you know for sure if there is a problem.

Share this post


Link to post
Share on other sites

Very informative discussion thanks guys, seems the glaze i'm using is pretty good and my general concerns are minimal which is great! Time for some glazing!

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

By using this site, you agree to our Terms of Use.