Thursday, November 19, 2009

How different RIO affects glaze

These 2 glazes are the same recipe, same firing and same shelf in the kiln, however the one on the left was glazed after I made a new batch with a bag of RIO that was noticeably lighter in color than the previous bag. The recipe uses only 3% RIO. I happen to like the new glaze better, but I'm curious how this will affect my other glazes. I tested Chris Wolff Plum and was hoping to make a full batch for my next firing. It uses 11.5% RIO. Any thoughts?

1 comment:

John Britt said...


All iron oxides have varing amounts of iron in them. You have to check the percentage. That is why some people buy a 50 pund bag so that it doesn't vary. (hard to use 50 pounds of iron oxide.)They do the same with rutile.

You may run another test with less iron to match your earlier sample, that way you can extrapolate the amount needed.

I am pretty sure that anything with 11.5 % iron will be a dark brown /black so you may be able to use 10% instead and we about the same.

Try synthetic iron sometime!