The warmth of the quilt will depend upon the thickness and kind of interlining you use. If warmth is desired, have a thick interlining which means that the quilting lines must be farther apart.
If the quilting is to be close and elaborate the interlining must be thin. When a bed cover of exceptional warmth is needed, use a comfort bat of cotton or wool. This will be too thick to push the needle through easily, making even stitches impossible. Instead of quilting, this coverlet must be tacked or tufted.
Cotton batting is most commonly used as interlining for quilts. One bat is enough for a quilt, unless it is over size. Four bats will make three extra sized quilts by using the length for width and piecing out the length. Sometimes a lightweight cotton blanket or flannelette is used, but the quilt will not have that soft puffiness that cotton gives. The best bat costs a trifle more but the finished quilt is a thing of beauty. If flannelette is used for padding, the breadths of cloth should be whipped together, as a seam will cause an ugly lump in the quilt. We never use sheet wadding as a filler for a cover that is to be quilted; it is much too stiff for easy work.