Turning white casting slip to beige?

[Mmplin]

Hello! I am trying to do casting with a slip similar to this but am pretty limited in my local options, only having white porcelain:

I know I'll need to add manganese to get the speckles, but does anyone have a recommendation on an addition to get the beige color? I thought a mason stain might be the way to go but am wondering if there's something else as it seems like I'll need to use a lot! Thanks so much for any advice 

[Babs]

The manganese may be giving the beige but clay body with manganese ĺooks pretty brown but fires beige so test additions of that. Safety hazard .

 can get body stains

The speckle would be granular Mn

Beiges colour MnO2

[Min]

If there is any chance of making your own casting slip instead of trying to alter a commercial one I would go that route. Claybody colour would be far less expensive to achieve by using darker firing clays. Manganese speckle might or might not stay suspended long enough in the casting slip to work, I'm not confident that the larger bits would, also the larger manganese particles probably wouldn't be on the outer surface of the cast so I'm not sure if they would show. An example of a similar colour casting slip here, the M340 revison 7 titled L3798G. It looks like it needs to go to cone 7 to get the absorption under 2% for functional work. (or it might tighten up enough with approx 1point 5 talc added for cone 6)