A Long Skirt is piece of clothing worn on the bottom. It can be dyed various colors. Long Skirt does not decay.
Use shears to turn a Long Dress into Long Skirt (as well as Button-down Shirt). Use shears on the long skirt to get Pleated Skirt.
To dye, you dip the cloth clothes in Simmering Dye Mordant to make them "dye ready", then dip them in your chosen dye color.