Barium blue slip!

[lewderry1]

I want to make a slip for high fire soda firing (neutral to light reduction) that has the dry property of a flashing slip as well as the color of Barium blue glazes (specifically the bright sky blue color they exhibit where thin) I have one firing to test this slip out before I start using it on my line of pots.  The solution I have come up with is a bit hackneyed but I've taken the average barium/strontium and lithium content, from online sources, for barium blue glazes and added that to a flashing slip.  I plan to test 6 different amounts of copper carb. From 2.5% to 5%.  If any of you all see any holes in my plan or apparent knowledge pls let me know. Also if you have a better means to my end would you be so kind as to inform me. I also considered useing tin and cobalt as additions to the flashing slip but was not as impressed by the color outcome of glazes I resourced with similar oxides and opacifiers.  

p.s. I have looked all over the internet and books in search of a slip recipe that could give me the results I am looking for with no luck. (maybe there's a reason for that) None the less,  I would very much appreciate receiving any recipes that you all believe may be similar to what I'm looking for

This is my test recipe:

Gail Nichols Flashing Slip

Grolleg 50

Ball clay

15 Neph Sye 15

Fine Grog 5

Alumina hydrate 15 

Strontium 24

Lithium 3

Copper carb 2.5, 3, 3.5, 4, 4.5, 5

Thank you very much,  -Lewis- -Asleep at the Wheel Pottery-

 

[neilestrick]

I've used copper slips in both wood and salt, and they can go anywhere from turquoise blue to copper red, depending on thickness, the firing atmosphere, temperature, degree of salt/vapor. I used a simple equal parts slip (kaolin, ball clay, silica, and feldspar) plus 6% copper carb. Because it's a slip, it takes a fair amount of vapor and glaze formation to get the color to come out. Slips just don't react to colorants the way glazes do, because the oxides aren't taken into melt in slips. I don't think you'll get much color response at the levels you're testing if the slip remains dry after firing.

[lewderry1]

Thanks for the insight Neil.  I am definitely going to bump up the copper oxide content in my tests.  I had known that slips require more colorants but I had thought it was only because of the opacity of the slip. so I thought that an opaque glaze would have the same amount of colorants.  I didn't understand the effect of the fluxing on the color.   

[neilestrick]

The other thing to consider is that the copper will fume out onto your other pots. I used to tumble stack copper slip pots on top of shino glazed pots and got some really nice colors in the shino.