Marking Half-Square Triangles

Half square triangles are common in a lot of quilt patterns, either as a standalone block or as a unit used to make up a larger block. The most common way to make half square triangles is to take two squares, draw diagonal line on the back of one of them, put them right sides together, stitch a quarter of an inch on either side of the line. Now that requires a lot of marking on your fabric or if you're making a lot of half square triangles, lots of lines that you need to draw. So I have a couple of tips on how to make sure that you're getting those lines accurately, right down the center of your square. So this was the two squares that I was going to put together. Obviously they'd be right sides together, I have multiple of them here, right sides together. And this is the wrong side of my floral fabric. So while I could still probably see my line, if I drew it in dark ink, if at all possible, always do your marking on a solid fabric or on that light color of fabric. So I'm gonna do my marking on this fabric here. Now, one thing when you are marking half square triangles as opposed to something like a flying geese unit, if you're marking those, is the line that you're drawing is actually a cutting line, as opposed to a sewing line. Anytime the line that you are marking is a cutting line, you can use pretty much any marking utensil you want and you don't have to worry about whether or not it is removable. So 99% of the time, if I'm marking a half square triangle, I am not using a quilt or sewing marking tool. I'm just grabbing whatever's in my home office and I'm using it. There are a couple of things you want to take into consideration if you're just grabbing a random pen or pencil and using that to mark your fabric. One thing is, if you're using a pencil, you wanna use as thick of a lead as possible. So I have one here that is a five millimeter lead pencil. And it's one where, a five millimeter lead pencil is one that has a very, very fine lead. If you're going to use this to try and mark on your half square triangle to draw the line because it is such a fine tip, odds are it's going to pull or scratch at your fabric. So you can see as I'm starting to draw my line, it's kind of wrinkling in that fabric and you might think, okay, I'll just press a little lighter with the pencil but then you're gonna end up having to go back and forth over your fabric several times to get a line that you could actually see. So if you're gonna use a pencil, make sure you're using a thicker lead pencil, one that isn't going to scratch at your fabric. Now, if you're going to use a pen, one thing you want to consider when you are picking your pen, is the width of the actual pen tip. So this one here is a lot wider because it has the silver part here. So you can see that it's a lot wider than the black part of this pen here, and you need to take that into consideration when you're drawing on your square. So if I were to flip this around since I already kind of drew in that corner, if I were to take my square and line up my ruler so that it is perfectly in the center of that tip and perfectly in the center of this tip and draw my line using my pen, and I'll draw it really, really dark, so you can see it. Because of the width of my pen tip, I am actually just slightly to the right of the center of that square. So I actually should have drawn my line over, right, like this, so I'm just drawing right to the left. That line actually goes from the center to the center. So you need to account for the thickness of your pen when drawing your line. So when you line up your ruler on your square, rather than having it go right through the center of those points, you need to back it off just slightly so that when you put your pen up against a ruler, your pen tip is in the center of your square rather than the ruler, because it might seem like just a little minuscule amount but maybe your pen is even thicker than this one. And what's gonna happen is that line that you drew that's off of the center, you need to be stitching a quarter of an inch on either side of it when you're making your half square triangle. And you're gonna end up with half of your half square triangles being just a hair too small and a half that are a hair too big. Obviously the ones that are a little bit too big, you can just square those down, trim those down and be just fine. But the ones that are too small, you might end up not being able to use them at all. So always make sure that you are accounting for the thickness of your pen, when you are drawing your line. Another thing when you're drawing your line is maybe you find that when you're using your pen, even though it's not a fine tip like the pencil that scratches at the fabric, but maybe you find that as you draw your line, your fabric buckles or moves like that. One thing that you can do that can help you make sure that you get a nice, consistent line all the way across, is to draw your line in two segments and actually start at the center and draw out to one corner and then start back in the center and draw out to the other corner. That way, your fabric never buckles or moves as you're drawing that line and marking it. And that will make it a little bit easier to do. Another thing that can help when you're marking your half square triangles is just making sure that you have a ruler that is the appropriate size for what it is you're marking. Now, this is a pretty small square, I'm using this two and a half inch by 18 inch ruler, which can get a little bit big and cumbersome if you have you know, a bunch of other things up on your sewing table. So maybe you have a smaller sewing table. You already have your machine up and ready to go and you don't have enough room to move this around. You can consider getting some square rulers to do your marking as well, but you definitely need to make sure that your square ruler is large enough to mark the diagonal. So while this is a square ruler that is the exact size of the square of fabric that I am marking, once I actually turn it to do the diagonal, obviously it's not long enough. So if you're going to get square rulers, make sure that the square ruler is long enough to do the diagonal marking. And if you have one that fits the right size, like this one here to where you can do the diagonal and have the 45 degree lines on your ruler to help make sure that your line goes directly through the diagonal, that square, that can even be another sort of helpful tip on how you can make sure that line goes right through the center of your square. So invest in some other smaller square rulers or some shorter rectangular rulers, and really think through your marking pen or pencil that you use and adjust where you line up your ruler. If you need to, if you're using that thicker pen, and with those tips, hopefully next time you sew a bunch of half square triangles, they all come out perfectly.