It’s your worst nightmare. Blocks that were cut the same size suddenly don’t fit together or line up. That 12 1/2″ bee block you spent ALL afternoon sewing is suddenly only 12 1/8″. The quilting gurus will tell you to double check your seam allowance, and to only use the same ruler for all your cutting. But the culprit might be sitting there right beside your iron!
Do not get me wrong. I love my starch spray. It is a great tool for stabilising fabric, it reduces fraying and helps stop bias edges on triangles from stretching out of shape. It is a valuable part of a quilters arsenal.
But did you know it also SHRINKS your fabric?
I conducted a couple of experiments which demonstrate this little fact, so often overlooked.
Here are my test rectangles. All of them cut exactly the same size from the same “virgin” fabric which had been lightly pressed for cutting but not pre-washed or previously starched. (Ignore my written width measurement, I was obviously having a dyslexic moment!) You can see the centre crease running across each of them – horizontally we have the lengthwise grain (parallel to the selvedge) and vertically is our crosswise grain (running from selvedge to selvedge).
Noted on each piece was the treatment it was going to be given – a hot iron, hot iron and starch, hot iron, steam and starch.
Here are the same three pieces of fabric after pressing, starching and steaming. Whoopee Cassie, all you did was make your pigment pen bleed. Whoops! But let’s look a bit closer shall we?
The lengthwise grain is described by Marti Michell as the most stable, and she is right. They didn’t shrink at all in width. However BOTH samples that were starched have shrunk along the crosswise grain. It’s only by a few threads worth, but now imagine this over a much larger sample…. or multiple pieces inside a block.
Ok, but that’s really not a huge difference. Why the big fuss?
I repeated the same test on this triangle using a hot iron and starch (no steam). It was cut at 2.5″ long. What I have highlighted here is that this triangle, because of the highly unstable bias on two sides, has shrunk a full 1/8″ – one eighth of an inch. That is 5% of the length of this triangle, gone.
Now imagine what this would do across a 12″ block? 5% of 12″ is .6″ – there is your missing seam allowance that you spent all day carefully sewing and pressing.
So, what’s the solution? Ditch the starch? No! Just be completely consistent in it’s application. If you are going to use starch, you have to use it from the very start, before you cut your blocks. Then the shrinkage has already happened and you can go on to use it to press stubborn seams and tame triangles to your merry heart’s content. If you use it on only selected fabrics in a block, you could have trouble with uneven block sizes and your seams might not line up.
However, there is a bright side to this – the knowledge that you can use this power for good! For example, I was piecing up some blocks this week that, due to my own laziness and “speed sewing” were not matching up. My side sections were larger than the centre sections every single time! I knew I hadn’t used starch on any of the fabrics, so I harnessed the shrinking power of starch. By laying out the side pieces only, and starching them, I helped to reduce the size difference between the sections, allowing me to easily pin and ease the blocks into submission.
Starch will always be a valuable part of my sewing and quilting kit – now I know how to use it, and keep it’s special powers under control! Please share or pin this tutorial, so that we can spread the word.