Tutorial 2. Doing Supplementary Calculations. Preparing to Cut the Petticoat.
I need to do all necessary calculations before I can start cutting the petticoat.
I already know the following measurements:
- Waist to Floor – 109cm. This is the key measurement.
- Mini-Skirt Length – 36cm
- Waist Circumference – 65cm
- Mini-Skirt Bottom Circumference – 100cm
- Train Length – 130cm
- Bottom Hoop to Floor – 13cm
- ½ Bottom Hoop Circumference – 150cm
I make a schematic drawing of my petticoat on the writing board.
And I need to find three additional measurements to cut the petticoat correctly:
- Front Petticoat Length;
- Back Petticoat Length;
- Side Petticoat Length.
I will start by cutting the mini-skirt, i.e. the top part of the petticoat joined with the rest of the dress.
According to the measurements, the mini-skirt has a length of 36cm and its bottom circumference is 100cm. Therefore, ½ of its bottom circumference is 50cm. In other words, I need to cut a rectangle (from thin elastic fabric because this part of the petticoat must not make the dress too thick). I will use knit lining fabric. You could also use stretch mesh fabric widely used in dancewear. Any thin elastic fabric will do. A mini-skirt sewn with elastic fabric will resemble a kind of a wide elastic band.
I need to know the dimensions of the mini-skirt including all seam allowances and additional allowance for inserting an elastic band to help it hold around the waist.
I will add 2.4cm to the supposed length of the mini-skirt (1.2cm seam allowance from either end) and another 3cm for the elastic band.
I will also add a seam allowance of 1.2cm to the half-circumference.
The rectangular piece of fabric for the mini-skirt must therefore have the following dimensions:
36cm + 1.2cm + 1.2cm + 3cm = 41.5cm
50cm + 1.2cm = 51.2cm
I suggest we should also calculate the length of the elastic band.
Tip: I always make the elastic band 10% shorter than the circumference of the area where it will be inserted. This 10% is enough to make it comfortable. Since my client has a waist circumference of 65cm, the elastic band must be about 58cm long.
Now I know all necessary measurements for cutting the top part of the petticoat.
The bottom part still requires some additional measurements though.
Front Petticoat Length.
I know my client’s Waist to Floor (109cm). The length of the bottom part of the skirt can be found by subtracting Mini-Skirt Length (36cm) from Waist to Floor. But I need to know the length of the petticoat and not the length of the skirt itself. And the bottom edge of the petticoat is positioned 13cm above floor level.
Considering the above-said, the front length of the petticoat is:
109cm – 36cm – 13cm = 60cm
I add a seam allowance for joining it with the mini-skirt part:
60cm + 1.2cm = 61.2cm
Back Petticoat Length.
Following the same algorithm as before, I will subtract the length of the mini-skirt and the distance from the bottom edge to the floor from the length of the train (130cm).
Personal experience, however, tells me that the train will look a lot more elegant if I remove another 5cm from the back length of the petticoat.
Thus the length of the petticoat along the back is:
130cm – 36cm – 13cm – 5cm = 76cm
I add a seam allowance:
76cm + 1.2cm = 77.2cm
Side Petticoat Length.
This measurement is simply calculated as the mean value between the front length and the back length. I divide in half the difference between the front length and the back length and add it to the front length of the petticoat.
The length of the petticoat along the side is therefore as follows:
60cm + (76cm – 60cm) / 2 = 68cm
I add a seam allowance:
68cm + 1.2cm = 69.2cm
All calculations have been done. But before cutting and sewing the petticoat, I must customize the factory-made petticoat which will serve as an inner supporting construction for the skirt.
I need to remove the hoops I don’t need and trim away the top of the factory-made petticoat.
There are seven hoops in this petticoat. I will keep the three bottom ones and remove the remaining four hoops at the top.
If you are using a petticoat with five hoops, you should leave the two bottom ones and remove the remaining three.
You can always use the removed hoops in the making of other custom petticoats.
Then I trim the petticoat so as to make it 61.2cm long along the full perimeter (the length is measured upwards from the bottom hoop). In other words, I give it the desired Front Petticoat Length with seam allowance included.
And now I can finally start working on the inner construction for my skirt.