I've been working on a silk chiffon dress this past week. I thought I would take a few pictures of how I mark dart placement when I just won't take the risk of putting chalk or air/water erase marker on a fabric. A sheer wedding gown is THE place to be paranoid that your markings just won't come out, even though you've pre-tested the method.
First of all, I'll start by saying that I almost never use commercial patterns. What you'll see in the following pictures is why. Every now & then, I'll go completely insane and think, "oh, this pattern is SO CLOSE to what I want, I'll just use the pattern and make a few corrections. If the amount of butchering done to the patterns in the following pictures doesn't frighten you, it should. It frightens me. It would have been simpler to start from scratch on alpha-numeric paper. This is actually two separate patterns laid on top of each other because I wanted the top of one & the bottom of another. I'm insane, I know.
O.K. I'll number this so it flows smoothly:
1) I lay the fabric on my ironing board wrong side up and then lay the pattern piece on top of the fabric. I secure with pins through all layers into the ironing board just outside the dart area so that nothing moves around. It's exceptionally hard to see the fabric here because it's a single layer of 8 mm china silk, but trust me, it's there.
2)I slice down the center of the dart in order to be able to move it out of the way. Then I fold back the pattern paper and place a pin where the mark is.
3) here, I'm holding both sides out the way in order to position both pins. Dang, when did my hands get wrinkly?
4) Holding back to place the center markings. You can see peaking out of the bottom that I've actually placed the point position pin first. It's just one more pin to keep the pattern from slipping around.
5) Just slip the pattern paper away (it's not pinned to the fabric anywhere) and you've got pins sticking into your fabric.
6) pick up a placement pin from one side of the fabric and slide it into the exact hole left by the pin on the other side of the fabric. In this example I'm taking the left hand center position pin and putting it right next to the right hand center position pin. Usually I'll take the right hand pin out and pierce the hole left by it, but I didn't think it would show up in a photo. I know it looks like I'm moving right to left, but I've moved around to the other side of the ironing board. The dart point is actually just out of sight on the top of this photo.
7) Here you can see the pins lying flat after having gone through both markings.
8)Now, pick the fabric up and start to pinch it together along the dart fold.
9)Don't let your pins come out! Now that you've got the fold pinched up, put a pin through a tiny amount of fabric just below the dart point pin, securing it to the ironing board.
10)put the pins through the fabric perpindicular (sorry, can't spell that) to the folded edge.
11)Now place a line of pins along your stitching line, connecting the previous pins
12)put your needle down through the fabric just above the top horizontal pin. backtack.
13)Take the horizontal pin out, start stitching. I snag the pin head of the vertical row of pins with my right hand fingernail and allow it to slide out of the fabric as I'm stitching.
14)When I get to the other horizontal pin, I stop & make sure that my sewing machine needle pierces the exact hole left by this pin.
15)Now just sew down to the point of the dart. This is probably a complete no-no somewhere in the annals of good sewing, but it's what I do because it works. I sew to the point of the dart, making sure that my sewing machine needle pierces the fabric at the exact same location of the last dart, then allow my sewing machine needle to make another stitch off to the right of the fabric. I then pull my fabric out of my machine & tie a triple knot loosely in the end & clip leaving about a 1 1/2 inch tail. Don't ask me if it's pretty, but my dart ends never snag and never pull out.
Hope this was helpful.