After I posted about the striped shirt I made for my stepdad a few of your expressed interest in a tutorial about how I added the slots to the underside of the collar to house collar stiffeners/bones/stays. So I've put a quick one together for you. I worked out how to do this by looking at a RTW shirt which had this feature and it's surprisingly quick and straightforward! It's my very first attempt at a tutorial so I apologise if any of my explanations don't make complete sense. Feel free to ask any questions you may have in the comments below.
Just to be clear before we start the slots need to be added to shirt before the collar is assembled. I'm not sure how you'd go about adding them to a shirt which is already made!
First things first you will need to cut yourself a third collar piece. If you are using a pattern which has separate upper and under collar pieces you will need one of the upper collar and two under collar pieces. Only the upper collar needs to be interfaced as usual. We will just be working with the under collar. If your under collar pieces are made up of two parts you can stitch those together along the centre before we begin.
Take one of your under collar pieces and, wrong side up, fold up the bottom corners (the corners which will be attached to the collar stand not the collar points). You want to fold them along a diagonal line which starts approximately 9cm along the bottom edge from the corner, and 5cm up the side. Give it a good press.
Now take your second under collar piece and lay it out with the right side facing up. Place the under collar piece with the folded corners on top of this piece also with the right side facing up (so the wrong side is against the right side of the piece underneath). Line up all the edges and pin in place. At this point you can baste together the long raw edges of the two pieces just inside the seam allowance but I didn't find it necessary.
Before we start sewing or marking sewing lines directly on to our fabric I found it useful to draw it out on paper first. You could do this directly on to your paper pattern piece or trace out another copy. We are now going to work out the placement of our collar stay slots which will be slightly different on each collar you make as it will vary depending on the size and shape of the collar and the length of your stiffeners if you have a particular set in mind. They are available in different lengths and but an average size is around 6.5cm from point to end and I based mine on this.
First draw on the fold line you made across the bottom corner (green line in my picture). Then draw on your stitching line so you can clearly see the seam allowances (red in my picture). Finally if you are going to be topstitching around the edges of collar when it is assembled draw this on at the correct distance away from the stitching line (purple in my picture). If you are not going to topstitch you can leave this out. We need to take this into account when positioning our slots as the stiffener will slide no further in than that line of topstitching and we need to ensure the length of the slot is long enough to contain them. If you are not going to topstitch you can leave this last line out.
Now use a ruler to find a line the length of your stiffeners (6.5cm in my case) which runs from the corner point of your topstitching line (or your regular stitching line if you are not topstitching) to your fold line. Draw this on in pencil.
This is the central line of our slot. We now need to draw on stitching lines either side of this line to make our slot just large enough to hold our stiffeners securely. Mine are 1cm wide (most are) so I have drawn lines parallel to the pencil line 0.6cm away on each side. These lines are black on my drawing.
Now transfer these two black lines to your fabric.
Stitch along these lines from the raw edge of the fabric towards the fold. For this tutorial I am using black thread so that it shows up nice and clearly in the pictures but of course you should use a thread which corresponds to your fabric. When you get to just a couple of millimetres away from the folded edge lower your needle, raise your presser foot and pivot the fabric around so you are lined up to stitch along the folded edge, sewing away from the collar stay slot.
And that's it! You can now assemble your collar as usual, using the piece we have just created as the under collar. Once completed you should have something that looks like this:
If you want some tips on constructing a collar (it can be a little fiddly!) I highly recommend this tutorial from Andrea at Four Square Walls. It's not failed me yet!