If the comforter label says machine washing is acceptable, or if the comforter is made of cotton, nylon or polyester satin, it is machine washable. Be sure to wash it alone in cold water. Use the lightest cycle on the machine (either "hand wash" or "gentle") to agitate the comforter less. If your washing machine allows, spin the comforter again at the end of the wash cycle to remove as much excess water as possible.
Wet satin must be handled with care, so be gentle when unloading your satin comforter from the washing machine. To remove excess water without wringing, lay out a large sheet on a flat surface and move the comforter onto it after washing. Smooth the comforter flat across the sheet. Roll up the sheet and comforter lengthwise to help press water out. Unroll and then re-roll in the opposite direction to press out additional water.
Machine drying is not recommended for satin of any type. A satin comforter should be dried on a large flat surface, indoors or out. A drying table needs to be large enough that the comforter barely drapes over the edges. If wet satin is draped over uneven items, like clotheslines, or hangs too far off the edge of a drying table, the fabric can stretch or tear under its own weight.
Drying the satin comforter on the ground or floor can prevent the wear issues caused by draping. Use sheets to protect your comforter from nature or accidental footprints. Place one sheet underneath the comforter to protect the fabric from dirt. Place another sheet on top of the drying comforter to protect the fabric from birds, footprints and direct sunlight, which can fade the color of the fabric.