Cobalt For Brushing Decoration - Keeping It Mixed...?

[Rex Johnson]

I'm still having a heck of a time trying to get my cobalt oxide and carbonate with water to stay consistent for brushwork.

I don't remember ever having this issue.

It just settles at the bottom of the jar, and very quickly making it hard to get a consistently loaded brush.

I like to use cobalt for alot of accents and drawing but it's always a pain...

 

Any ideas?

 

[neilestrick]

Add gum solution, or a little bentonite, or use underglaze instead.

[Marcia Selsor]

or you could mix up an appropriate slip base for the cobalt. Like ^6 green or a bisque recipe to ^10.

Marcia

[Rex Johnson]

Add gum solution, or a little bentonite, or use underglaze instead.

This stuff? Great, I will give that a try.

 

[Magnolia Mud Research]

I always first mix cobalt colorants with  a little alcohol to get all the particles wet.  I add that to the water carrier.  The alcohol reduces the surface tension at initial contact and keeps the particles from forming lumps.  It does not prevent settling. 

 

To cope with the settling, I have used a cobalt blue water color tube paint instead of cobalt oxide/carbonate to make cobalt marks over glazes or bare clay.  It must be a paint make with cobalt pigments, not just blue pigments.  I just dip a wet brush into the paint and paint.  Acrylic paints work to but they will act as resists if you want to add glaze over the painted area. 

 

LT

[neilestrick]

 

Add gum solution, or a little bentonite, or use underglaze instead.

This stuff? Great, I will give that a try.

 

 

 

Yep.