About gouache color palette

The hard cover is not easy to maintain the humidity in the paint box, while the soft cover can easily retain moisture and prevent the paint from drying in the box. Hard-covered paint boxes usually have a sponge inside the lid. After squeezing out the paint or every time you finish painting, you need to wet the sponge and cover it with the box and then close the lid. This will keep the paint moist for a period of time. However, if you don’t use it for a long time, you still have to moisturize the sponge. Will dry.