Nickel Unreliable?

[Babs]

I have been looking thro' old recipes from the past. One I had discarded , well, 2, because of unreliability in results. I put it down to nickel as the colour i liked, i would not always get. Possibly the unreliable factor was me..I do not have photos as  the pots, successful and unsuccessful. are no longer with me. Same clay body used, same application method, dipping. Test again I hear you all say.

Before I do, has anyone had similar unreliable colouring resulting from using nickel oxide, firing to C 5/6

I'll get the recipe from my shed if that would help?

[Norm Stuart]

Nickel gives you a lot of creative options if you have the control over what's happening - as it can become so different things.

 

So I guess that could be an backhanded way of of saying the resulting look of the glaze can be unreliable depending on the chemistry.

 

This is nickel silicate (Garnierite).  Nickel sulfites, chlorides and fluorides are all various shades of green.

 

Excess Nickel crystallizes out of a glaze as it melts., but it's far more soluble in glaze than chrome which crystallizes out as ugly brown dots..

 

So if you add an excess, the cooling speed is going to greatly affect the look of the glaze.

 

This is a  "glaze"  I call Olive Speckle.

100     Ferro Frit 5301

    6.3  Nickel Oxide

    1     Bentonite

 

Seen here are four different guises.

 

1.) This is fired to Cone 06 - Most likely undissolved green Nickel Carbonate which was the starting ingredient in this case, or Nickel Silicate crystals over a brown nickel glaze.

 

 

2.)  This is the same fired to Cone 04 in a bisque firing, so there's more carbon monoxide around and it cooled more slowly. More nickel has remained in the glaze resulting in a deeper yellow brown.

 

3. & 4.)  And finally, these are the same "glaze" with an extra 10 grams of Silica - fired to Cone 6 with a slow-cool and a fast cool, showing various combinations of nickel. Both are likely Nickel Fluoride using fluoride from the frit.  Notice the bubbles and the pinholes not annealed in the fast-cooled tile on the right.

 

Nickel Fluoride

[Babs]

Here's the recipe, the colour shich I seek and have acheived , then lost some times is  teal blue breaking to honey on rims and edges, a matt glaze.

Looking further is appears that Nickel is temp. and atmosphere sensitive and so I may be going a bit high and it may depend on the loading, to acheive this effect. Also noticed that nickel is not used a s a colourant much in higher cone firings.

Frit 3110 50

Silica 200 30

Zinc oxide 20

Nickel oxide 2

Red iron oxide 1.

Using it on a white body.

ANy confirmation or explanation for unreliability of this glaze?

[Norm Stuart]

Babs -  I'll make a small batch of your glaze and post a photo of what it looks like.

 

Bear in mind three potential differences.

 

1.)  I will use 3.2 nickel carbonate as that's the only nickel source I have on hand currently;

 

2.)  As you mention, Black Nickel Oxide Ni2O3 is only 90.32% Green Nickel Oxide NiO, so if you bought green it might have oxidized leaving your recipe with too little nickel, or if you bought black this provides 10% less nickel than green NiO;

 

http://digitalfire.com/4sight/material/nickel_oxide_black_1074.html

http://digitalfire.com/4sight/material/nickel_oxide_green_1967.html

 

3.)  We now add a six hour slow-cool to our ^6 firings.  (50 F per hour between 1,800 F and 1,500 F) (27.8 F per hour between 982 C and 815 C)  So my tile will likely look different if cooled at a much faster temperature.

 

Here's the recipe, the colour shich I seek and have acheived , then lost some times is  teal blue breaking to honey on rims and edges, a matt glaze.

Looking further is appears that Nickel is temp. and atmosphere sensitive and so I may be going a bit high and it may depend on the loading, to acheive this effect. Also noticed that nickel is not used a s a colourant much in higher cone firings.

Frit 3110 50

Silica 200 30

Zinc oxide 20

Nickel oxide 2

Red iron oxide 1.

Using it on a white body.

ANy confirmation or explanation for unreliability of this glaze?

[Babs]

Right , my nickel is grey black , named nickel oxide but this name may just be a simplification.

 

EDIT As I still use a manually controlled electric kiln and would not be following any of your schedules, and very rarely firing down, your testing of this glaze would not be relevant other than to reveal if you can in fact produce the teal matt I am after, then of course, it would be highly unlikely that I would be able to acheive  your results.

Be interested to know if you get the blue, but would it be a consistent result.

Is nickel a beeeeech to work with?

[Norm Stuart]

You need more zinc to get more blue - more cowbell.

 

 

Here's the recipe, the colour shich I seek and have acheived , then lost some times is  teal blue breaking to honey on rims and edges, a matt glaze.

Looking further is appears that Nickel is temp. and atmosphere sensitive and so I may be going a bit high and it may depend on the loading, to acheive this effect. Also noticed that nickel is not used a s a colourant much in higher cone firings.

Frit 3110 50

Silica 200 30

Zinc oxide 20

Nickel carbonate 3.6

Red iron oxide 1.

Bentonite 4

Using it on a white body.

ANy confirmation or explanation for unreliability of this glaze?