Flat Lining– What is it and why do we do it?

Flat lining is a style of lining where the fashion fabric is joined to another fabric and then treated as a single piece. This is often used in conjunction with bag lining on the same garment. The flat lined piece has the look of the fashion fabric but the physical properties of the flat lining fabric. Once the union is complete, the fashion fabric and the flat lining are then treated as a single piece of fabric.

One reason we might do this is because often when we choose a fashion fabric the fabric is chosen for appearance and maybe not for the innate qualities of the fabric such as strength and support. For example, I have made a supportive bodice from tissue silk that has been flat lined to cotton duck. Alone, the tissue silk is thin and would in no way be able to be a supportive bodice on its own. When it is flat lined to the cotton duck, the tissue silk then has the properties of the cotton duck and has strength and support for a bodice.

So to flat line you cut your fashion fabric and you cut the same pieces out of the flat lining. You then stack the flat lining piece with the fashion fabric directly on top of it, wrong side facing the flat lining piece. Once the pieces are properly lined up, pin around the entire piece.

Next, you sew around the entire piece with a very narrow seam allowance that is narrower than the seam allowance that will be used when you join the bag lining to the fashion fabric. For example, I sew a 15mm seam allowance normally. When I am sewing the fashion fabric to the flat lining, I sew at a 10mm seam allowance so that when I sew the bag lining on at 15mm, the stitching from the flat lining is in the new seam allowance and will not show on the finished garment.

So for this garment I started the process by laying out my cotton duck panel.

I then placed the fashion fabric panel on top, wrong side to the cotton duck flat line fabric and pinned all the way around.

Once safely pinned, I machine stitched all the way around the panel at a 10mm seam allowance.  I also zig-zagged the bottom of the panel as that was cut on the straight of grain perpendicular to the salvage and was fraying badly.  These next two photos show the front and back of this single panel piece now.