Folded triangles are called prairie points. These are used as edgings for the neck and sleeves of garments. It is also used in patch work and quilts. These triangles can be made singly, but it is laborious.This problem can be solved by doing continuous band of triangles. It is also called Continuous prairie point or picket fence.
First step is to calculate the width of the material required. The following formula is used to calculate the width of the fabric needed.
Height of the triangle needed x4 + ½” for seams = width of the fabric strip to be taken
If the height of the triangle needed is 1” The width of the material taken should be 4½”
Take the strip of material of required width and length (Figure 1}.
Fold it into half along the length keeping wrong sides together as shown in Figure 2. Press well. Open the fold. X-Y is the fold line.
On the wrong side of the material draw lines M-N and O-P parallel to the fold line X-Y and ¼” away from the fold line, these are the seam lines.Divide the fabric above the line M-N and below the line O-P in to squares as shown in the figure 3 by drawing lines. Cut along these lines till you reach lines M-N and O-P.
Cut and remove the half squares that are at the ends as shown in Figure 4.I have named the squares above the line X-Y as 1,2,3,……and the squares below the line X-Y as 1b,2b.3b………….
Let us now consider square no 1 that is above the fold line
Join corner B to corner D and press. Do the same thing for all the other squares that are above the fold line.
Similarly the squares at the bottom of the fold line are folded by folding them in different direction as shown.
Now the fabric strip looks as in Figure 5
These triangles are folded again .Second fold is done in the direction as shown in the figure 6. We get small triangles on either side of the fold line X-Y
Finally third fold is done by folding along the line fold line X-Y
Each fold should be pressed well.
Secure the triangles in place by stitching along the seam line. Continues triangles
If we have to use these triangles on curves bias strip of cloth should be taken. The triangles are secured by running stitch not by machine stitch.