These Mason stains make the porcelain more refractory, but some more so (e.g. 6385, 6226). Some do not develop the intended color (e.g. 6006 pink, it is a glaze stain only). Some need a higher concentration (e.g. 6121, 6385). Some need a lower concentration (e.g. 6134). Some do not impart a homogeneous color (e.g. 6385). The data sheets from the stain manufacturer normally make it clear which of their stains are suitable in bodies. But it is up to you to test concentrations needed to get the desired color and what adjustments to the porcelain are needed to compensate its degree of vitrification in response to the effects of the stain.
Ceramic stains are manufactured powders. They are used as an alternative to employing metal oxide powders and have many advantages.
In the ceramic industry, refractory materials are those that can withstand a high temperature without deforming or melting. Refractories are used to build and furnish kilns.