Yes. Using SATTVA rose water as a liquid base for powdered face masks is one of the intended uses and fits well with a simple Ayurvedic-style beauty ritual. It is a simple way to use the toner when you want a more substantial treatment than a quick spray.
Place the powdered mask in a small bowl and add the rose water little by little while stirring. You need just enough to make a smooth paste that spreads easily and does not run. Starting with a small amount of powder is helpful, because you can then adjust the consistency without waste. If the mixture is too thick, add another drop or two of rose water; if it is too runny, add more powder.
Apply the mixture to clean, damp skin and avoid the eye area and lips. Follow the suggested time from the mask manufacturer, and do not leave it on longer than instructed. Rinse with lukewarm water and continue with your serum or moisturiser. Since every mask powder is different, check the instructions on the mask first, and do a patch test if you are not familiar with the powder. External use only.