Decipher Your Quilt - Why would you call that a 16 or a 25 patch?

We have had some great questions in the last couple of posts of Decipher Your Quilt, so today Jess, Elven Garden Quilts, and I are going to focus providing a bit of clarification - a sort of Dear Jess and Leanne type post.

First I wanted to remind you what we are doing in this series. Our focus is to give you the concepts and information we use to allow us to figure out how to make quilt blocks without a pattern or tutorial. We are sharing how to decipher your quilt.

In that process, we have to have some working definitions and as I mentioned at the beginning of the series, these are just our ideas and approaches. We are not the quilt police nor are we authorities on quilting; we are just pretty good at geometry and basic math. Interestingly as we start to talk about more complicated blocks like 16 and 25 patches, it becomes clear that there are many ways in the quilting world to define or refer to these blocks. And when the blocks become complex there are even more differences.

For example, let's look at the block above. Jess calls this block Another Star. EQ7 calls it Girl's Favourite. When you look at it, you might see a bottom row of the white square, the star points with the fancy orange block and the white square. Then a middle row of the large white square with the yellow corners and the same star points and fancy orange block just turned 90 degrees, then the top row which is a mirror of the bottom row.

The problem is that without more you cannot easily make this block without a pattern. You don't know how big that thicker middle bit is compared the the bottom and the top row. You will not know the measurements of the pieces to end up with a 12" finished block, for example.

But, if I lay over it a 16 patch grid of equal size squares, I now recognize this block as a 16 patch. I can figure out the sizes of units within the block to make that 12" finished block - each square in the 16 patch would need to finish at 3" on each side (12" divided by 4 = 3).

Once I know that each grid square is 3" finished, I can see that the centre 4 squares will join together to be a 6" square. I can piece that part as 4 HSTs or I could instead piece it as a square with yellow corners added.

The same goes for the star point parts. I could piece each square in the 16 patch grid (do you see how those squares are quarter square triangles) or I could piece that part differently so that the orange square can remain as an unbroken square of fabric. Both will give a similar but slightly different looking result.

The trick to being able to decipher it - that is to figure out the measurements you need to allow you to piece the block -  is the same no matter how you decide to piece the block in the end.

One more example. That quilt above is made up of 25 patch shoo fly blocks. Now when I piece this block, I piece it in 9 pieces, like a nine patch. But when I decipher it and calculate my sizes I am "seeing" the 25 patch grid superimposed on the block.

If you imagine a 25 square grid over the block you will see that the corner HST units are made of 4 blocks each of the 25 square grid, the long white middle sashings are made up of 2 squares on the grid, the centre square is made of one square on the grid. Although the block certainly looks like a 9 patch, and I would construct it in 9 pieces, I calculate it as a 25 patch.

So if I want these shoo fly blocks to be 10" finished blocks, I will know that the centre square will be  2" square. The white sashing will finish at 2" wide by 4" long. The corner HST units need to finish at 4" squares.

I am not likely going to make these blocks to be 12" as the math is harder because it is a 25 patch. It is harder to divide 25 by 12 and then cut and use fabric pieces that size, but I could easily make the blocks to finish at 5" or 15". Compare that to a 9 patch block which easily finishes at 6", 12" or 18", but not 5", 10 or 15".

The take away point is that the approach you might take to construct the block will often not be the approach you take to decipher the geometry and the math in the block. Jess is explaining this same concept today on her blog, Elven Garden, Quilts, you will want to read her explanation too. Let me know if you have questions.

We will be back in two weeks to decipher odd-ball blocks.

Best,

Leanne