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How-to Slash and Open

Slashing and opening is the process of cutting into a pattern and spreading it open to add or to transfer width or length. It’s a simple technique and is used for many pattern drafts and alternations. Ruffles are created when a pattern is slashed and opened through the entire width or length of the pattern. Flares and flounces are created when a pattern is slashed and opened at one point and tapered to nothing at another point. For the sake of preventing this post from turning into a textbook, I will limit my scope to slashing and opening to transform a block, pencil, or any straight skirt into a flared skirt.

When slashing and opening to create a flare, there is one key principle that must be noted. The width that is added to create the flare must be added at several points and not all at one point. If the pattern is slashed and opened and all the additional width/flare is added at one point or if the all the additional width/flare is added at the side seam, the finished garment will have one large flounce as opposed to many flounces throughout the entire skirt. I don’t think you want one large flare on your skirt, now do you?

With that said, now we can get started.

Using your block, pencil, or straight skirt pattern, draw several (at least 2 or more) vertical lines from waist to bottom opening. There really is no formula or right number to calculate the number of lines to draw. I have drawn 2 lines and I have drawn 6 lines; it all depends on the particular pattern and the amount of width/flare to be added. The way I determine the number of lines to draw is to find the number that divides into the amount of width/flare to be added evenly. If 6” of width/flare is to be added, I draw 3 lines and open the pattern 2” at each point. If 12” of width/flare is to be added, I draw 3 lines and open the pattern 4” at each point. Also, make sure that the lines drawn are evenly distributed at the waist as well as at the bottom opening, even if that means the lines become angled near the side seam. Once the lines are drawn, slash/cut the pattern along the lines and spread the pattern open the desired width and the bottom opening, tapering to nothing at the waist. Lastly, true the bottom opening curve (TIP: When truing, butt the front and back skirt patterns together at the side seam and make sure the bottom hem transitions smoothly from front to back ((or vice versa)) and that the point where the side seams meets the bottom opening is at a right angle. If this point is not a right angle, the skirt will point up or down when it is sewn).

Originally published  as a guest post on the blog A Good Wardrobe



  1. Reply


    I love skirts with that sort of movement and hem shape and have often relied on a dirndl, but prefer the clean waist of a circle skirt. Thank you for sharing how to create the skirt! It’s another for the to sew list!

  2. Reply


    I am using your directions to flare the gores of a princess seam on a blouse, both front and back. I am wondering if this will interfere with the bust measurement since the flare will cut through the bust line and essentially add more width. If so, is there a way to start the flare at the bust line and flare from there to the hem of the blouse? If so, can you tell me how to do that? I do understand that I need to use 2 or more vertical lines when adding in my flares. Last question – is there an ideal number of inches for a flare, or at least a starting place? Thank you!

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