For the purpose of the experiment, I have made two very similar corset dresses. There is always a room to improvement so when I was making the second dress I decided to use an invisible seams method. That means that the bones will be placed at the inside, but the seams or bones will not be visible on the outside of the dress. This method gives smooth and clean finish. But no matter which method for the construction you choose, it is most important to start with a good pattern.
Usually it is considered that the U-plunge fits only to big cup sizes (C-cup and over), but with the help of some foam inserts and the satin ribbon it can give a delicate look even to the smaller bra cups. The corset dress is made of a 12-piece corset pattern (both corset dresses were made for petite figures and small bra cups, and I haven't tried how the deep U–plunge would work on a 14-piece pattern).
Taking the Measurements
For making the deep U-plunge corset dress pattern you will need all the usual measurements as for standard overbust corset pattern which are already described here. Take all the measurements described, including waist to bottom edge of corset, as you will first need to make a pattern for the overbust corset.
For the modifications of the pattern you will need some additional vertical measurements:
As this is a deep U-plunge overbust pattern you should measure from the waist to top edge of corset (1) at the deepest point of the plunge on the centre front. For the highest part of the plunge measure the apex to the top of the corset over breast (2). For the construction of the bottom part of the dress measure the waist to bottom edge of the dress (3). You will also need to measure from the waist to start of widening into pleats on the front (4). Decide where you want the bottom part of the dress to start to extend into pleats on the front. I suggest you take this measure somewhere between high and low hips, just a bit under the iliac crest. If you position this measurement too high, you will lost the effect of corset dress giving a support in the abdominal area, and if you position it too low, the dress will not follow natural lines of the body.
Start with an Overbust Corset Pattern
I personally like to draft all my patterns from scratch, but you can also use a pre-existing pattern for any vertical seamed or classic Victorian corset. It is only important that the corset is fully closed at the back and that the final pattern have panels with approximately similar width redistribution in the waist area. It might be necessary to adjust the pattern to achieve that. By that transformation you will reduce the bottom width of the front side panel and extend the widths of the front and middle front panels. If you use the pre-existing pattern then you can redistribute the widths as shown:
The redistribution of the widths is important because later you are going to extend the pattern for the bottom part of the dress. As you can notice on the original overbust pattern, the side front panel is the widest compared to other two panels. The first two panels need to be widened at the bottom and the side panel needs to be reduced so the seams of the bottom part of the dress are redistributed more equally. Also any other pattern for the vertical seamed overbust corset would work but I personally prefer angled Victorian cut as it gives the curvier silhouette than the vertical cut patterns.
If you decide to draft your own pattern from the scratch, be guided by the same rules as for transforming the pattern; no gap at the back, and bottom widths of panels redistributed as equally as possible.
After the transformations are applied on your own drafted pattern, it should look something like this:
Now the real work on the pattern transformation begins...
Transforming Overbust Corset Pattern into the U- Plunge Corset-Dress Pattern
The top side seam on the front panel is extended for the amount of apex to the top of the corset over breast measurement. Follow the changes on the middle front panel so they match. Shape the deep U-plunge as shown on the diagram. If you are not sure you have shaped the plunge right, do not cut it out on the mock up - just mark it with the pen. Then you can check the shape and amount of the plunge on the body, readjust the marks if necessary, cut it out and try the mock up once again.
You can also decide on the other shapes of the top front part and bust area if you do not prefer the plunge shape, or you can even go with the underbust variation of the dress, what would make the pattern drafting and the construction of the dress even simpler.
For the shorter versions of the dress (up to 10cm above the knees), the bottom circumference of the dress should be about 2.7-3 meters, and for longer versions I suggest you plan 3 meters or more. It also depends how rich you want it to be and how strong is the material you are going to use for the construction of the dress. Divide the desired bottom circumference by 12 to get the approximate amount you need to widen the bottom part of the dress on the each panel. That amount is approximate, because the panels are not equally wide at the bottom, so you will need to extend more on some, and less on others.
For extending the bottom parts of the dress start with the front panel and extend the center front for the amount of waist to bottom edge of the dress (1-2). From that point to the right measure the approximate amount of widening of the bottom on the each panel and leave the mark (2-3). On the side seam of the front panel, measure from waist to start of widening into pleats on the front (4-5), and from that point draw an angled line for the widening of the bottom part of the dress. That line should go through the mark you left in the previous step (point 3). Then measure from the last mark on the bottom of the center front (6-2) and transfer the length from the same mark on the side angled line of the side seam you draw in a previous step (7-8). Transfer the length once again from the mark somewhere on the middle of the pattern (9-10) and shape the curved bottom edge of the front panel of corset dress. Redistribute the total bottom circumference on a way that a bottom part of each panel closes a similar angle, and for the fullest volume of the dress that angle should be about 45 degrees.
For the middle front panel repeat the same steps, and for the side front panel, start widening a bit higher than on the previous panels. On the side seam the pleat should start falling from the iliac crest. As you can see on the photo, more circumference amount is redistributed on the front side panel as that panel is wider than the other two panels.
For shaping the back panels it is much easier as you can start the widening for creating the pleats directly from the waist.
After all changes are applied, the finished pattern for the corset dress should look similar as on this diagram, and now the panels are ready for adding the seam allowances. Don't forget to add more on the bottom as you might need it for finishing the bottom edge of the dress.
Cut the modesty panel in a rectangle shape. The panel should be about 12cm (4.7") wide, and it should be long enough to cover the whole opening of the dress at the back. Make it at least one inch (25mm) longer than the position of the last eyelet on the bottom of the dress.
Mock up and fitting
I suggest you always make a mock up for the corset dress pattern. Not only for testing the length, but it is also important that the dress fits on a way that is fully closed at the back.
This corset dress is made for a first time corset wearer. Wearing a corset dress is a bit harder than wearing a regular overbust corset, as this type of the dress should be wear fully closed at the back and the wearer will not be able to loose the laces if the dress is too tight in the waist area.This model is a bit longer at the bottom, approximately reaching knees area.
As I took the measures before the summer and continued two months later after the unbearable heat cooled down, the model lost some weight - especially in her bust area - so I had to adjust the fit on the bust area. The top part of the dress needs to be shortened, as this is an A cup and there is actually not much to lift up.
Also as you can see the waist to start of widening into pleats on the front measurement is positioned too low so the red marks shows where the lower part of the dress should start widening.
At the side, the dress should be cut a bit deeper under the armpits and the pleats on the side seam should start from the iliac crest.
The back can go higher on the top and the pattern is a bit too tight at the back high hip area, where should be extended for half an inch (13mm) on each seam (red mark).
Fabrics for construction of corset dress
For outer layer I recommend the strong material and coutil is the best choice possibly. But as it is hard to get coutil in any other color than few main - black, white and nude (and that is something that the looms should considering to offer, as there is more and more corsetmakers and the demand already exists), I wasn't able to get any so I had to be satisfied with a red twill.
I was considering the option of dyeing the coutil with DYLON dye, but I have never tried it before and I didn't want to risk unequal finish or the poor tone of the color - so I decided to use standard herringbone black coutil for strong layer, and red twill for the outer shell, reinforced with some interlining.
For the outer layer you will need at least 1.5m (1.64 yards) of material, depending on how long and how wide you want the dress to be and how tall the person you are making the dress for is. Do not forget to wash the material before you start cutting, to prevent the further shrinking due to the wearing or cleaning. Sort the pattern on the fabric so the waist line of each panel is vertical to the weft, and for saving as much of the fabric as possible, face one pattern up and other in opposite direction, as shown on the picture:
You can add seam allowances on the paper pattern or you can add it directly to the material, whichever you prefer. Add the seam allowances as usual, as they will not be used for any boning casings.
Cutting the Fabric and seam allowances
The coutil layer should be cut the same as you are making an overbust corset. You don't want to cover the whole inside of the dress in the coutil as it would be too much - just the top, "corset" part of the dress. I suggest not cutting any of the coutil yet until you decide which method you will use, so you can add appropriate seam allowances.
The twill I used is not so stiff as the coutil, so I decided to reinforce it with an interlining.
Note that when you are cutting the interlining, you need to make it shorter than the coutil layer, so it will be fully covered by the inner layer of the coutil. Also, I do not recommend putting the interlining on the parts that are widening into pleats. Keep the interlining on the "corset" part of the dress. Cut the interlining shorter at the side panels.
Construction of the outer layer of corset dress
Start by cutting the fabric as described and attaching the interlining if you are planning to use it. Then stitch the seams together.
Press the seams open and cut out the excess of the fabric on the each seam to alleviate the bulk. Then press both seams on the same side so the all seams on each half of the dress are turned to the back of the dress. (That means the seams from the center front panel are pressed on panel two, and so on, etc.)
I have finished the seams that will be visible on the inside of the dress with the overlocking machine. Note that the top "corset" part of the dress will be covered with the layer of the coutil, so if you decide to use the same method, you don't have to overlock the entire seam, just the part that is not covered by the inner layer of coutil.
I was also thinking of some more sophisticated finish of the inside seams. If you are making dress from the single layer coutil, you can fold the seams into the boning casings what would be one possible solution. As I wasn't using the seams of the outer layer for the boning casings, I had to cut them to prevent the bulk. I think the binding the seams into the thin satin binding in matching color would be the most sophisticated solution. If you have any suggestions about this issue, please leave it in a comment, as I always want to consider all possible solutions.
Baste the waist tape on the inside of the outer layer.
After this the out layer is ready and next you need to do is attach the boning channels on the coutil layer if you have choose the invisible seam method.
In Part 2 I will show you how to finish the construction of the interior (coutil) layer of the corset dress using the invisible seam method.