What Is This Stuff?

[oldlady]

mixed up a batch of glaze for a friend.  it had red iron oxide in it.  lot of it, almost 20%.  there was nothing else in the mix that was dark enough to hide this stuff that i could not get through the 60 mesh sieve.  it is black and looks like fine sand.  some was stuck in the mesh and i had to wipe it out with a sponge when i finished the glaze.  the RIO is the spanish RIO i bought well before 2000.  there was a lot more of it that got tossed into the yard.

 

have make this glaze before and it is a beautiful color but i do not remember the sieve problem.  

[Pres]

I dont know, but it looks like granular manganese or granular rutile used to add speckles to clay bodies and glazes in the ^6 range. I don't know as regular iron oxide would have that in it unless contaminated in some way.

 

 

 

best,

Pres

[Babs]

Thought it looks like ilmenite or rutile, would give good colours to an iron glaze.

[Benzine]

Some of my low fire glazes, I use in class, have something like that in it.  It doesn't go through my screen either.  

[Marcia Selsor]

I think it is just part of the iron. I get it too.

 

Marcia

[Benzine]

The question is, does that need to be in the glaze?  Should I add it back in, when it doesn't go through the screen?

[neilestrick]

Looks like iron to me. I get that, too. It's generally not enough to alter the glaze.

[Joseph Fireborn]

When I use a low quality iron oxide or a more natural iron oxide I get those when I screen my larger batches. When I use a more synthetic iron oxide I never get any of that stuff.

 

So I am guessing it is a result of the spanish iron oxide. I also have a high purity iron oxide that doesn't give that as well. It is interesting to think about the differences between them. I also get a lot more speckles when I use a lower quality iron oxide compared to a synthetic one. Just a few things I have learned over the last few years. I have tried about every iron oxide I could find from pottery suppliers. My favorite is axners blend. It results in the brightest reds and no speckling when used in light glazes like creams or whites.