Mulling with cotton flannel

Before cutting into your pattern, you should make a few copies. Depending on the pattern peice your going to need different seam allowances.

Covering a buckram form is not as difficult as it would seem. If you take easy steps to ensure success, this project should not take long to complete. First of all you should have all of your materials ready. Don't prewash, unless you are allergic to sizing, it's not bad to leave the factory finish on materials for your bonnet. Also keep in mind that you cannot get your bonnet wet. Buckram is sized with glue. The glue is water soluble and will disintegrate when wet. So don't go out in the rain in your bonnet.     

The main reasoning behind prewashing your fabric in sewing projects, is to preshrink your material before you make it into a garment. This implies that you would actually wash on your bonnet which you're not going to do! So why go through the hassle of  prewashing your fabric?  What you should do however, is make sure all of your fabrics have been pressed with a good amount of steam. You're going to want to make sure that all of your grain lines are square so that you can find the bias.

You're going to cut 2 on the bias of both the brim and crown pieces. Using whatever is your favorite method of marking, mark the seam lines on both the brim and crown pieces. My favorite method is using pins and wax tailor chalk. I pin through my pattern and both layers of fabric and using my wax chalk I mark the seam allowance. You will also need to  mark the center line.

Once you have made all of your marks, match right side to wrong side. It doesn't matter if the crown is stacked on top of the brim, or the brim is on top of the crown. You need to however, match centre marks and pin running down the seam.

You are doing this strange seam consconstruction to reduce on seam bulk. The purpose of the mull layer is to smooth and soften the buckram form. You want to reduce as many bumps as possible. 

Using a three-stage  zig zag stitch, sew the crown and brim together. Do this to both the the exterior and interior layers. Once the seams are done, trim your seam allowances to as close as possible without cutting the sewing threads. Trim both the brim and crown seam allowances.

To apply the mull layer to the buckram form, you will be sewing through the buckram form and into the mull. You can either do this by machine or by hand. One trick I have learned though, to temporarily attach the mull to the buckram form, is to use a small amount of steam from your iron and soften the buckrams glue. This will stick down the mull long enough to be able to sew it in place.