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nepheline

india ink or what else ?

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Ahh, good point Callie.  I was so busy looking for materials I ignored the context. 

Though I don't think it's food safe, I wonder if registrar's ink would work. It's an ink used when officiating weddings over here; it gets darker over time for a better record in the wedding records for signatures etc.  I think it's an iron gall ink.

https://en.wikipedia.org/wiki/Iron_gall_ink

 

Edited by hantremmer

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Thanks for the suggestions and comments.  Partly, I'm intrigued by the idea of using an ink that's designed to last and to see what happens - even if there are tried and testing ways of acheiving the same look.

 

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Ware we getting precious here.

Probably ingest/absorb more baddies walking down the average street.

What poisons are in Indian ink??

The total body load on intake over a lifetime to be considered

Just saying 

After a number of washes as said above the stain in your mug would be more tannin than anything...

 

Poor washing and personal hygiene more health threatening imo

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11 minutes ago, Babs said:

What poisons are in Indian ink??

I believe they are made from soot and some have binders added. I'm wondering about tattoo ink. 

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A quick Google search for India ink MSDS reveals that most brands are certified non-toxic. As Min says, it's just lampblack. Will it kill you? No. Is it foodstuff? No.  

Check for a MSDS for the brand you use just to be sure: the binders that different manufacturers use might affect things.

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I bought the registar's ink.   I was told that it writes blue, but oxidises black.

I brushed it over the crackle on my pot a few days ago.  It brushed on blue, but hasn't gone black.  The colour has shifted from blue to an egg-shell blue / slight grey.  It's not as vibrant.

Maybe it will continue to change in the coming weeks or months, but it's not  what I hoped for.  That's OK though, because this was an experiment.  I don't have any reason to think it's an issue with the ink.

There was also a lot of feathering in the cracks, where the ink has seeped into the clay.  Perhaps I used too much or it's some other reason.  The glaze has crackle, but that's not its selling point.

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2 hours ago, Min said:

@hantremmer, thanks for posting your results, good to know. Are you going to leave it as is and see what happens over time or re-fire to burn off the registrar's ink and try something else?

I'm going to leave it and see what happens.  I have fired pots again, but moreso to get different results rather than better ones.   Also  I don't have a kiln, so I have to follow the timings and rules of the studio I go to. 

 Babs,

What would heating the pot do?

Edited by hantremmer

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Expands the cracks a bit so ink can get into the cracks a bit easier but care as too hot and it' s hard to get the ink off the glaze.

Edited by Babs
additional info

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Thanks Babs.  The glaze cracks were wide enough for the ink to flow, so that wasn't an issue this time I don't think.  Out of interest how would you recommend heating the pot - in an oven or something?

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6 hours ago, Babs said:

Expands the cracks a bit so ink can get into the cracks a bit easier but care as too hot and it' s hard to get the ink off the glaze.

I've found that heating does the opposite. In one crazed vase I have, the cracks disappear when you soak it in hot water, but then reappear once it's cooled. This makes sense to me, since there's no tension in the glaze at the temperature that it solidifies, but then the tension increases as you lower the temperature, due to the difference in thermal expansion between the glaze and body. So heating the pot should reduce the tension, and therefore shrink the cracks.

But you aren't the only one who suggests heating a pot expands the cracks; Nigel Wood talks about this in his book on Chinese Glazes.

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11 minutes ago, Pieter Mostert said:

I've found that heating does the opposite. In one crazed vase I have, the cracks disappear when you soak it in hot water, but then reappear once it's cooled. This makes sense to me, since there's no tension in the glaze at the temperature that it solidifies, but then the tension increases as you lower the temperature, due to the difference in thermal expansion between the glaze and body. So heating the pot should reduce the tension, and therefore shrink the cracks.

But you aren't the only one who suggests heating a pot expands the cracks; Nigel Wood talks about this in his book on Chinese Glazes.

Could be because the clay body expands more than the glaze when heated?  If you were heating only the glaze it would be like what you were saying? Seems like there's a lot of room for difference experiences based on the body and glaze involved

Edited by liambesaw

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2 hours ago, Pieter Mostert said:

I've found that heating does the opposite. In one crazed vase I have, the cracks disappear when you soak it in hot water, but then reappear once it's cooled. This makes sense to me, since there's no tension in the glaze at the temperature that it solidifies, but then the tension increases as you lower the temperature, due to the difference in thermal expansion between the glaze and body. So heating the pot should reduce the tension, and therefore shrink the cracks.

But you aren't the only one who suggests heating a pot expands the cracks; Nigel Wood talks about this in his book on Chinese Glazes.

In good company then!:-))

Maybe you need a Chinese glaze for it to work.....

Getting above temp of hot water....

In an oven I put the ink on when warm/ fresh out of the kiln....not a cool unpacked here

Edited by Babs

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10 hours ago, liambesaw said:

Could be because the clay body expands more than the glaze when heated?  If you were heating only the glaze it would be like what you were saying? Seems like there's a lot of room for difference experiences based on the body and glaze involved

If the clay body expanded more than the glaze when heated, it would shrink more than the glaze when cooled, so the glaze would be under compression, and wouldn't craze.

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7 hours ago, Babs said:

In good company then!:-))

Maybe you need a Chinese glaze for it to work.....

Getting above temp of hot water....

In an oven I put the ink on when warm/ fresh out of the kiln....not a cool unpacked here

I wonder if a higher temperature simply makes the ink less viscous, allowing it to penetrate the cracks better, even if they're narrower. This link doesn't specify what type of 'ink black' they're measuring, but it shows a dramatic decrease in viscosity between 20 C and 50 C: https://wiki.anton-paar.com/en/ink/

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Yeh may be so!

And as the pots cool in the kiln it is then that the illfitting glaze cracks up.....

A past moderator here described the ink application as flowing the ink on not painting it on. And further to immerse the pot in the ink  if possible.

It is interesting to note that the "always have done it this way" may be barking up the wrong tree or for the wrong reason..

Beetroot always a good test for well fitting white glaze...

 

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Update -

The ink has started to appear underneath the pot where it's unglazed, the footring is pretty much entirely blue, though in different shades and darknesses.  It doesn't seemed to have changed colour from the light blue / grey under the actual glaze.

 

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