It is not mandatory, however, using a base coat offers a layer of protection between your nails and the nail wrap.If you have naturally oily or uneven nail surface, a layer of base coat can help the nail wraps adhere better to your nails.We find that there is no difference as to which base coat you use.If you intend to wear them beyond 10 days, do apply a layer of base coat to protect your nail from moisture seeping under the nail wrap over time.