Red color has alum red, gold red two categories, alum red is how to color?

Alum red coloring agent is iron oxide (Fe2O3), it is also known as iron red, is China's traditional red color, began in the Song porcelain. Alum red is made of alum (Fe2SO47H2O), calcined and rinsed. Need to add the right amount of lead powder and glue in color painting. Alum red color tone and the fineness of the color material, the finer the powder, the more vivid the tone. Alum red color color is also related to the baking and burning temperature and time, if you can master, you get bright red, if the temperature is too high or too long, will make part of the iron oxide dissolved in the bottom glaze, and make the red color tone flash yellow.