You can re-use the sheetmasks of Skin for Skin. The package of the sheetmasks contain a big amount of serum. This means that you can put the mask back in the package after use, in this way you can re-use the mask again! Moreover, you can store the extra serum in our serum bottles. You can add a serumbottle to your order of your masks. Pour the remaining serum into the bottle and apply it daily and/or nightly underneath your moisturizer.