Hi all,
Grain alignment or aligning a bra pattern parts to the weave of the fabric.
For the wings of the bra the alignment should be with the greatest stretch of your Powernet going around the body, so the grain line on the wing pattern part runs from CB to the cradle / frame / cup seam line with the line parallel to the bottom hem of the wing. If your Powernet stretches by the same amount in both warp and weft directions then you can follow either weave direction.
For the cradle and centre front bridge of a bra made from non-stretch fabric, again the grain line runs around the body parallel to the bottom hems of the cradle / CB bridge.
As with all non-stretch fabric parts of a bra it is always a good idea to use a lining to prevent bias stretch, remember some woven non-stretch fabrics stretch at 45 degrees to there weave line.
With the cups and there fabrics, we need to make sure there is no fabric stretch in any of the panels that make up the cup or the cup will go out of shape.
You should first look at any printed or woven pattern on the main outer fabric and align the cup paper pattern parts to this so you do not get the fabric pattern running in one direction on one panel and in other directions on the other cup panels, this also goes for lace fabrics.
When you have aligned your cup paper patterns to your main cup fabric mark on the paper cup patterns the direction of the main fabric weave, then take your paper cup pattern parts and place them on your lining fabric with the new marked grain lines aligned at 45 degrees to the weave of the lining fabric. In this way you will have the straight weave of the lining fabric cancelling out the bias stretch of your outer main cup fabric as the two weaves will be at 45 degrees to each other when sewn or fused together.
And finally, if you wish to use Galloon Lace Tulle for your cups remember the embroidery along each edge must be opposite i.e. left and right handed (see part three of the bra making articles for a full explanation of Galloon Lace Tulle)

I hope that helps 
Corset Hugs
Mark