Often you may find that the fabric has been stretched on the bias, or off of the "square" and you will need to check for this. You can determine that the raw edges are straight (in all the fabrics I've used anyway) by cutting a one or two inch notch into the fabric parallel to the cut edge, and tearing fabric to make a clean edge. Then fold fabric in half with the selvages (or woven edges) of fabric together, and see if the raw edges match up. If not, pull fabric by opposite corners (it's helpful to have the friend handy again for this) until all edges line up. When it is done you should be able to fold the fabric into quarters and have each edge meet up perfectly. Then pull the fabric on the grain each way, and iron to stabilize the fabric.
On most fabrics the lengthwise threads are stronger, and there are more of them. Most garment patterns are marked with vertical grain line, because to hang properly they need the strength vertically. With corsets the strongest part of the fabric needs to run horizontally around your body to bear the tension of lacing. If you have used my instructions for making a corset pattern you have marked your grain lines running horizontally on the pattern. If you are using a purchased corset pattern it probably uses vertical grain lines, which may make my directions confusing. Just remember, regardless of how the lines are marked on the pattern you are using, orient them so that the strongest (least stretchy) direction of the fabric runs horizontally to bear the tension.
The best way to cut the pattern is to cut each piece separately, and to use a rotary cutter. This needs to be done very meticulously!!! But keep in mind that inconsistencies in the way the pieces are cut can affect the finished product. And the more panels you use the more dramatic this effect can be.
If you lack the patience for this you may cut all lining and all fashion fabric at once (I find that, despite the changes that can occur in cutting multiple layers of fabric - from fabric shifting or the blades cutting at an angle through the fabric - that I create even more variance in separately drafting each piece if I am not in a patient mood). If you do this make sure your scissors (or rotary blade) are sharp!
If you wish to cheat and cut all the pieces out at once see the following illustrations. Note that these illustrations show the selvage oriented for canvas. The selvage on your lining fabric may be oriented differently, depending on which direction the weave of your fabric is strongest.
First lay out fabric according to illustrations, and press. Draft pattern on fabric, then unfold fabric and insert interfacing as instructed. Press fabric again to bond interfacing before cutting.
If doing the traditional construction method with a single layer of lining fabric fusible interfacing is not necessary. See illustration 'A' for fabric layout.
If using alternate construction using one layer of lining fabric, see illustration 'A'. Insert interfacing between steps one and two. Lining and fashion fabric will be fused together and treated as one layer.
If using traditional method with two layers of lining fabric, use fusible interfacing to fuse one layer of lining fabric to your fashion fabric. See illustration 'B'. Insert interfacing between steps 2 and three. One layer of lining fabric will be fused with fashion fabric to treat as outside layer. Second layer of lining fabric will be stitched separately for lining.
If using alternate construction method with two layers of lining fabric see illustration 'B'. One layer of interfacing will be inserted at step 2 to fuse both two layers of lining. Interfacing will be inserted again between steps two and three to fuse both layers of lining fabric to fashion fabric. All three layers will be fused into one. This is best suited with thinner fashion fabrics that need the extra support of two lining layers. With heavy fashion fabrics it may be too bulky, and probably unnecessary.
Most pieces will have a seam allowance of 5/8 inch added to each side, so allow adequate spacing for this. The inside edge of each center front piece will have 1 inch added, for inserting and anchoring the busk.
Center back will need about 1 1/2 to 2 inches allowance (enough for width of eyelets to be used, plus width for two strips of boning, and a little extra to anchor raw edge in the last seam of the second boning channel) If you need wider allowance for larger eyelets, or if you wish to make corset slightly tighter all over than you could fit the pattern (for tighter lacing), you should plan to add to or subtract from this ammount accordingly.
If you wish to reverse the direction of some pieces to conserve fabric you may, unless you are using velvet or fabric with a one-way pattern.If using self-fabric for boning casing, strips should be about 1 1/2 inches wide. These will be cut with grain, and self-fabric bias-binding for tops and bottoms should be about 1 1/4 inches wide and will be cut diagonally to grain.
As close to the edge and as accurately as possible, trace the outline of each piece with a sharp fabric pencil (this will be where each piece is stitched, but these lines will not be needed after you have added the seam allowance and cut out the pieces). Mark lines for waist, top, and bottom matching lines by starting line at pattern edge. Rather than continuing line at the angle at which it intersects panel piece you will instead draw it out at an angle perpendicular to edge of fabric.* This way if you are matching up two pieces whose edges curve differently, the matching lines will still meet up accurately at the stitching line. Also transfer busk top and bottom lines on center front pieces on the wrong side of lining fabric.
After drawing the outline for each panel, remove pattern and number accordingly, starting numbering with center front. Using a dressmakers' measuring tape or ruler, carefully mark a new line exactly 5/8 inch out from from stitching line, and be consistent about distance all the way down! When doing curved or angled areas, go out from original line at an angle perpendicular to curve.* When all pieces are marked and numbered, smooth out fabric(s) again.
If you will be cutting multiple layers at the same time, and aren't using fusible interfacing, carefully pin layers of fabric together to prevent them from shifting when you cut. Keep the layers as flat as possible as you pin. Insert pins horizontally, and use at least three pins - one at top, center, and bottom. Use more if tops or bottoms are more than a few inches wide, or if the fabrics tend to shift.
Always cut in the same direction to prevent fabric from shifting or pulling on the bias.
When each piece is cut out, snip a small notch (either a small triangle or just a straight snip - I find that just a straight cut is more accurate, although less easy to see) on each matching line, less than halfway into allowance. Do NOT cut all the way in to stitching line!
Keep multiple layers pinned together until all are cut and numbered. The layer of fabric you first traced your pattern on to will always be marked A, and numbered one through however-many-panels-you-have. Be sure not to mark any pieces upside down!
Now reconnect the lines through panel between notches (the same as you did when first transferring pattern), most important is the waist line. If you are working on a light color you may want to mark the line by basting or hand-stitching with contrasting thread. Continue with all pieces, numbering them appropriately. If you don't have pets or people who are going to rearrange things it's easiest to separate them into four piles now (or two if using alternate method) 1A- ?A lining, 1A - ?A outside, and 1B-?B, etc., etc. See if the line markings are visible through both sides of lining/facing fabric. Pencil will usually go through. If not, redraw them on other side, this may be helpful later. If pieces are cut with edges on a strong bias (diagonal to grain), carefully press them to help stabilize fabric and prevent panel from stretching out of shape. You may also want to stitch close to the edge of the panel to further stabilize it, being careful not to pull or stretch.*