Intricate painting with Iron Oxide

[AlanArmstrong]

Hello,

 

After running many experiments I have hit a wall with achieving the results I am looking for.

Any friendly advice or guidance welcome. 

My aim is to create intricate illustrations  with black iron oxide, maintaining clean line work and topping with a clear high gloss glaze.  

 

My problem is that the designs are bleeding out and blurring in the glaze tests and turning yellow.
 

Unglazed, the line-work is lovely and crisp but  I would like to use a clear glaze to seal for tiles.

Any ideas? I am firing to cone 6 in an electric kiln. 

 

Many thanks,

Alan

[Min]

Hi Alan and welcome to the forum.

Iron tends to get bleached out by the calcium that is found in most cone 6 glazes. I don't know what is available on your side of the pond but you might want to look at using either a brown underglaze, or a brown and black mix of underglazes, or a ceramic stain mixed with a frit to help it adhere to the pot plus some kaolin.

[AlanArmstrong]

Thanks for answering, I am pretty determined to use black iron oxide to paint with as I use it interchangeably with wild clays and foraged iron  so really just looking for a transparent glaze that will fit it really. 

[Min]

How much experience do you have with glaze chemistry? Do you mix your own glazes or use commercially prepared ones? If you mix your own how in depth an answer are you okay with?

 

[Callie Beller Diesel]

In addition to the calcium, if the lines are blurring your glaze may be too fluid for this purpose. But as Min already mentioned, we need more info to tailor answers. If you could let us know which clay body you’re using, that would also be helpful.

[High Bridge Pottery]

How convinced are you to work at cone 6? I have one that works pretty well at cone 03, not that my brush detail is intricate on this test but it doesn't spread. Red iron oxide mixed with water.

 

Low Expansion Frit - 43

Ferro Frit 3195 - 43

Kaolin - 14

https://glazy.org/recipes/440793

[AlanArmstrong]

On 9/11/2024 at 4:05 PM, Min said:

How much experience do you have with glaze chemistry? Do you mix your own glazes or use commercially prepared ones? If you mix your own how in depth an answer are you okay with?

 

Very little experience with glaze chemistry, but keen to learn. 
 

I have been using Amaco HF 9 clear glaze, purely out it being the first clear glaze I was introduced to so it’s all I’ve known. 

On 9/11/2024 at 5:07 PM, Callie Beller Diesel said:

In addition to the calcium, if the lines are blurring your glaze may be too fluid for this purpose. But as Min already mentioned, we need more info to tailor answers. If you could let us know which clay body you’re using, that would also be helpful.

I am using Amaco HF 9 clear glaze on stoneware. 

 

On 9/11/2024 at 8:41 PM, High Bridge Pottery said:

How convinced are you to work at cone 6? I have one that works pretty well at cone 03, not that my brush detail is intricate on this test but it doesn't spread. Red iron oxide mixed with water.

 

Low Expansion Frit - 43

Ferro Frit 3195 - 43

Kaolin - 14

https://glazy.org/recipes/440793

I am keen to try anything to fulfil the vision I have for my work.

 

To clarify, I am very fixated on using iron oxide to paint with as I have used iron oxide in other areas of my work outside of my ceramics practice and so excited to work with iron in a new medium, in addition to it being such a raw material to work with, I’m just trying to find the right formula for achieving my vision. 

In ceramics I am wanting (but so far not achieving) to paint intricate line drawing designs on my stoneware plates, tiles etc.

My most successful tests have been using iron oxide:clay:water/gum 

Fired without a clear glaze I get beautiful crisp linework, but with the clear glaze the lines blow out into a yellow tones. I’m firing to cone 6. 
 

Clear glaze recommendations for maintaining crisp line-work underneath would be greatly appreciated or any other hints or tips for working with iron oxide.  

Thanks in advance and many thanks to all who’ve replied so far 

 

 
 

 

[PeterH]

Any relevance to the glaze experts?

Cardew's Red aims to suspend Fe2O3 crystals in a glaze body in which Fe2O3 is insoluble.
... with a significant emphasis on no Ca and other alkali earths.

 

Edited Thursday at 03:04 PM by PeterH

[AlanArmstrong]

20 hours ago, PeterH said:

Any relevance to the glaze experts?

Cardew's Red aims to suspend Fe2O3 crystals in a glaze body in which Fe2O3 is insoluble.
... with a significant emphasis on no Ca and other alkali earths.

 

This sounds like what I’m looking for.  Last night I read in Phil Rogers book on Ash glazes (an excellent resource) that anything with ‘high calcia content will run or diffuse if placed over iron slips thus destroying any pattern made in the underlying slip coat’ (pg 85) 

…so this is definitely where I need to further my tests and find a glaze that fits my ironwork.
 

Any input greatly appreciated.  

[Min]

If we have a look at the recipe and formula mentioned in the thread above there are some alterations to make to the glaze to get it to melt at cone 6.(info from that thread at the bottom of this post) Either boron (from a frit or Gerstley Borate) or zinc will be needed to flux it enough for midrange.

For boron the obvious choice would be Ferro Frit 3269 as its a boron frit with very low calcium with no other alkaline earths but it also contains zinc. However, it is very high in sodium,( Na2O), and potassium, (K2O), which is likely to increase glaze crazing from their high Coefficient of Expansion (COE). So to adjust the glaze to reduce the COE there must be either Lithium added at the expense of some of the K2O / Na2O or one of the low COE alkaline earths, magnesium, (MgO), would be a good choice. Problem with this is then you are back to alkaline earths washing out the iron, albeit less so with MgO than CaO.

Second problem to address is the colour response zinc can cause with iron. Granted there isn't a great deal of it with Ferro 3269 so this might or might not be an issue if you can come up with a formula using it with lithium to counteract the high COE plus increase the Al2O3 and SiO2 would be necessary to make a workable midrange glaze. Might be somewhere to start if you want a deep dive into glaze chem and testing.

 

44% North Cape nepheline syenite
34% Potash felspar
20% AB clay
2%  Kaolin

... which is attempting to achieve
0.8 K2O
0.2 Na2O
1.17 Al2O3
0.05 Fe2O3
5.35 SiO2

edit: for the purposes of this discussion I have left the flux ratio out of the equation but it should be considered.

Edited 8 hours ago by Min

[Babs]

There is some where a black which iz  acheived by a mixture of iron oxide, cobalt and Manganese dioxide. 

This doesn't discount the above info but certainly gets to a black black. Some primitive and ancient potters get a great black.