Use a hand operated mortar sprayer : THE MOUSTIC®. It project much more regularly and is more powerful than the others. Approximately 130€ should be counted to acquire one of them, if not you can rent some in any hirer out of building material.
Do not forget to ensure you of the good state of the combs because it happens that the machines of hiring have some missing combs (the hirers out forget sometimes the visit in the "dentist" and to make replace the few missing teeth:o)))
For this work, a special coating "Tyrolean" is used, more practical!! But you can produce a mortar containing white cement tinted with oxides. To obtain and see immediately the wished color, take a little this mixture on a trowel and made quickly dry it on a flame.
This stage is carried out in two master keys minimum. The rather fluid first of consistency is used to standardize the support (the professionals say that it is enough to tint).
To be read ... 
