[Clayart] Ron Roy. Please try to tell me WHY!?!

[Dale Neese]

Terry, 
There are certainly more variables associated with red iron oxide in a glaze
formula plus not to mention how it is fired, clay body and so forth. 

I am not a chemist that can readily tell you what is happening with your red
iron oxides in the glazes. I know from my own experience that to get the
results I am after the thickness of glaze application has a great deal to do
with the fired results. If you add more red iron oxide to your current left
over glaze bucket you might get unintended results since red iron oxide is a
pretty good flux and therefore could make your glaze run off the pot than
change the color. 

If you are like me I can't afford to take chances with a questionable glaze
especially if I have a load of ware I want to glaze with it. Everyone hates
to waste glazes and pots so I'd rather mix a new batch, test it before
committing to glazing a lot of pots with it. Pour your questionable glaze
into gallon containers and add it back into your new mix a little at a time
if the fear is wasting a glaze. It shouldn't alter the result that you can
tell. 

Further reading about iron oxide can also help you discover the possible
causes of your dilemma.
https://digitalfire.com/4sight/material/iron_oxide_red_874.html

Dale Tex
"across the Alley from The Alamo"
Helotes, Texas USA
www.daleneese.com