How to Use a French Curve

French curve template

Do you know how to use a French curve template for drafting or altering patterns? We ran across the following tutorial in the February/March 2014 edition of our sister magazine, Sew News, and just had to share! Written by Marla Stefanelli, the article appeared in Sew News' May 2003 edition, and was republished as part of the magazine's new "Best of the Basics" column in which tried and true sewing advice is salvaged from past issues.

French curves are used in drafting patterns or making pattern alterations. Invented in the late 1880s, the French curve is used by mathematicians, engineers and sewists alike. Technically a French curve is a drafting tool used to connect points in a smooth curve. It's used for garment pattern drafting and alterations, especially for necks and armscyes when trueing and blending seamlines.

Drafting 101
Trueing a line is the process of straightening seamlines to establish correct seam lengths. Blending is the smoothing, shaping and rounding of angular lines for a smooth transition from one point to another. Trueing and blending are often done at the same time.

Easy Alterations
For most home sewing, the fashion curve is used mainly for pattern alterations when fitting, changing or adding new design lines. Choose a fashion curve to make the following four pattern alterations:

• When cutting out and lowering a dart and lowering to match your bust point, the sideseam becomes uneven. Use the ruler edge that closely resembles the pattern line to draw a new, or "true," cutting line (Fig. 1).

• Use a slash-and-spread method to add width to a pattern piece, using the long curved edge to draw the new cutting line at the outer edge (Fig. 2).

• When your body curves where a pattern line is straight, add a curve to the pattern. Measure your body and mark the corresponding point on the pattern. Then use the curved edge to connect the points (Fig. 3).

• To lower the neckline, mark the desired depth on the pattern. Then place the ruler so it intersects the original shoulder cutting line and aligns with the new mark; trace the resulting curve (Fig. 4).

TIP: When drafting an especially long line, flip the ruler over to draw a line evenly from both sides of the seam to achieve a smooth symmetrical line.

Click here to find out how you can discover more sewing tips and tutorials from Sew News.

Sew On, Sew Well, Sew Beautiful,
Cyndi & Amelia