Yes, the liner can be used as a cover while proofing.

Proofing sets are essential tools for any bread baker. When selecting a proofing set, there are a number of factors to consider, ranging from the shape and size of the baskets to the quality of the materials and the extras included. Look for a proofing set that uses either rattan or cane baskets, both of which are excellent materials for proofing bread. Rattan is a strong material that is porous enough to create an ideal environment for proofing dough, while cane is a lightweight material with a smooth surface that creates a slightly more consistent proofing environment. The size of the baskets should be taken into consideration depending on the loaf size you prefer. Basket covers are also an essential part of any proofing set. They keep the dough warm and prevent it from drying out. The basket covers should be made of a breathable material, such as linen or cotton, and should fit snugly around the baskets. A good proofing set will come with both a metal and a plastic scraper. The metal scraper is better for removing the stuck dough from the baskets, while the plastic scraper is better for removing dough from the countertop. A scoring lame is used to create decorative designs on the top of the sourdough loaf. Most proofing sets come with a scoring lame and a set of blades. It is important to select a scoring lame that is comfortable to use and has high-quality, durable blades.