For removing the powder of a Maria Stuart rabbit-felt hat, you should use one soft brush. A stiff may tear / damage the hat. When brushing the hat, do it always in the same direction.
A damp cloth can be used to remove dust and small spots. Gently, rub the wet cloth in a counterclockwise circular motion over the surface to quickly remove dust / stains.
For stubborn stains, use an anti-stain spray (dry cleaning) for delicate fabrics. Do not leave for a long time, it is preferable to repeat the process.
The inner cotton belt should also be cleaned. For that, use a damp and little soapy cloth, and then a non-soapy cloth to remove the soap. This technique can also be used in the felt and the outer straps, however, must always use little soap to prevent soap stains.