14 September 2011

Half-Square Triangle Block

Over the last week I was working on blocks for a quilt block swap on Flickr, which I've already mentioned in a couple previous posts, the Nubees Block Swap. The block design that I came up with is a half-square triangle configuration (I've been doing a lot of those HSTs of late, I notice!).

When I posted the photos to Flickr, I was asked where I found the pattern, so I answered as best I could, but in all honesty, I pretty much just played around in my sketchbook with different HST configurations until one jumped out at me as being able to highlight 3 main colors (with some inspiration from a great ol' book I've had for years - Spectacular Scraps, by Judy Hooworth and Margaret Rolfe).

So, here is a little tutorial on these blocks (measurements are for a 12" finished block):

Start with a background fabric, plus 2-3 main colors (I chose to use prints that combine the 2 or 3 colors for the center section, then focus the middle and outer sections on one color each). You will need a total of (8) 4" squares of the background - mine is the grey solid, and (12) 4" squares of your prints - I went with 4 prints for each of the 3 sections.

Now, I will preface this whole thing with the warning that there IS a fair amount of waste in this, unless you choose to do multiple blocks with the same fabrics (in which case you will need more squares of the background fabric), or you don't mind having triangles in your scrap basket. Myself, I prefer to keep my scraps to squares, rectangles and strips, so this was a little tough for me (I actually still have a pile of all of the extra triangles from doing the swap blocks that I can't get myself to discard or cut down just yet). Alrighty, on with the lesson!

Take your squares that will comprise of the center diamond and the outside corners only (4 background pieces and 8 prints) and cut them once, diagonally.

We will be using both halves of the background squares, but only one half of each of the prints. I

Stitch blocks together in pairs, one background triangle with one print triangle, stitching along the long side.

Now, for the middle section HSTs, take a slightly different approach, as we will be needing both sides of all of the 4 prints *(unless you choose to use a more scrappy approach, which I'll touch upon at the end of the tutorial). Instead of cutting the squares diagonally, just pair up a square of background with a square of print, right sides together,
and DRAW a diagonal line from corner to corner. There are many tools for this. I tend to prefer using either a blue water-soluble marker or one of the Bohn or Sewline ceramic chalk mechanical pencils.

(the marking lines are a little faint for the photos, but trust me I could see them!)

Use the pencil lines as guides for your 1/4" seam allowance. Stitch 1/4" on either side of the line.

At this point you should have: (4) 4" squares of a background and print fabric stitched together on either side of a diagonal center line and (8) triangle pairs of one background fabric and a print.

Next step, cut along the center line on the (4) squares, to get (8) more triangle pairs. Press open, with the seam allowances all going to the same side (background if you used a darker color, otherwise press toward the prints on each).

After your blocks are pressed, it's time to trim them down. They need to measure 3 1/2", and will likely need 1/16 - 1/8 inch trimmed to acheive that. The best way to trim and square up HSTs is to use a rotary cutting ruler that has a 45 degree guide line from at least one CORNER of the ruler. Line this guide up with your center seam, making sure the edges of the block extend beyond the 3 1/2" mark on every side.
Cut along two edges, then flip the block around, lining up the trimmed edges exactly to the 3 1/2" guides on the ruler. Trim the other 2 sides.

Now for the fun part! Lay out your blocks on the table, keeping your 3 sections separate - (4) HSTs making up the center diamond, (8) HSTs making the faux flying geese sections surrounding the center, and then (4) corner blocks. We will be making a block that is 4 rows of 4 blocks each. If you picture it in quarters, have all of the print fabrics pointing in toward the center. Play around with configuration until you land on a combination that feels balanced. Lay out the blocks with the final orientation on your sewing table.
You may choose to leave the blocks laid out as such, as you start piecing your rows across, but I like to make tidy piles, so that I can work on more than one block at a time (again with the chain piecing love!) I just stay consistent with how I stack my blocks, going from left to right, top to bottom.

Sew your blocks together into the horizontal rows, then press. For this swap I chose to press my seam allowances open, which allows the recipient more flexibility in putting his or her various blocks together. For myself, I would choose to press seam allowances to one side, alternating directions on each row.

Then piece your rows together, matching up block corners at the seams. Anyone who knows me in real life knows that I am not much of a gadget person - I have the basic tools and use them to the best of my ability and advantage. HOWEVER, I will say that I LOVE the Clover fork pins for matching seams and points.

Press seams (open) and VOILA!

*Coming back to that scrappier look... to do something like this guy:
...the only real difference will be in the number of print fabrics you start with - 16 total instead of just 12. And you will begin by splitting ALL of your initial 4" squares diagonally before stitching, since you won't need both sides of any of the print fabric (for just a single block).

Whew! I hope this doesn't leave anyone with more questions than they began with!! Have fun and do me a favor by leaving me a message if you try this tutorial and let me know what you think. Thanks for stopping in!


  1. Thanks so much for making this tutorial! You did a great job explaining the process of how to make it, and the pictures really help explain the process. I'm going to try it out for next months block swap!

  2. I was searching for a way to use 5 colors plus a dark background. I used this block for 4 of the colors and used the 5th for the light border. Thanks for posting it. Here is a link to my blog for a peek at it under construction.