The un-talked of enemy of those who work with silk. What is it? Seam Slippage occurs when the seam is solid, but the threads/fibers to either side of the seam start to pull away, resulting in a gap in the fabric. This typically occurs when not enough stitches per inch are used during crafting the seam, and are more likely to occur on seams that run parallel to the selvage, along the warp of the fabric.
It is also prone to happening with silk. This is mostly due to the filament nature of the fiber itself. Silk is slick, and that slippery tendency includes having the filaments migrate away from the seam stitches, especially at stress points. But not all is lost. There are actually several steps you can take to avoid this catastrophe.
First, shorten your stitch length. The average stitch length for commercial sewing machines is 2.5 mm or 10-12 stitches per inch. Shorten that to 2 mm or 12-13 stitches per inch. May not seem like much, but it makes a big difference in seam strength for silks. Always make sure your seam allowance is at least 1/2 inch. This is so you can do the next step: flat fell your seams. Or use French seams. Really any double row of stitching is effective in combating seam slippage. Binding the edges is NOT effecting against seam slippage due to the binding occurs on the outer edge to prevent fraying from the outside in, but does not really strengthen the seam itself.
And preventing slippage is that easy. Seam allowance, stitch length, flat felling. And however much you may hate flat felling seams (I HATE flat felling seams…I prefer pinking sheers and call it good. I am a lazy seamstress in that regard), you will hate more having poured your heart and soul in to making the perfect gown, only to have the characteristics of the fiber destroy your efforts from the inside out.