Sew a Fine Seam – Why Imperial?

Welcome to a new series of blogs that will concentrate on aspects of patchwork and quilting for the beginner but those who have enjoyed the craft for some time may also pick up some hints and tips.

You may be an experienced seamstress or tailor, or not touched a needle since your school days but learning to make quilts a fantastic skill.  I always say that when learning P&Q you are learning two different crafts.  Imaging a family tree – one for patchwork and one for quilting.  You travel up the trunk of the patchwork tree and find that it splits into many, many different branches.  Do you prefer hand sewing or machining? Let’s take the hand sewing branch. Oh look, appliqué – needle turned, fusible or raw edge? The machining branch is the same, each splitting into infinite branches down which your needle may take you.  

Once your top is made we then have to tackle the quilting tree.  Again, hand or machine?  The machine branch can split into domestic machine, mid or long arm. Walking foot or free motion. When you first start it’s easy to think that the simple baby quilt you are making as a gift is all that is involved but it is just the first step of what, for some of us, is a lifelong journey.

In this series I’m going to cover a few of the basics to help you take your first steps.  I am a firm believer in ‘learn the rules like a pro,  so you can break them like an artist’ – a quote from Picasso – and he was right.  Often, I have found those basics I learnt at my local quilt shop (LQS) years ago hold me in good stead for problems I face now. 

So, where do we start?  With sewing a fine seam.  In patchwork we use a 1/4″ seam allowance which is narrower than we use when sewing other items, the standard being 1.5cm (5/8″).  

We use inches in patchwork and quilting “but why?” I hear you cry.  There are a couple of reasons.  Firstly,  a lot of the patterns we use originated from the pre-decimal era. In America patterns were printed for public use in magazines and newspapers and were available to purchase by post from the mid 1800s.  These were obviously in Imperial and are a wonderful source to explore.  

Secondly,  the 1/4″ seam allowance is easier to measure than the exact metric conversion of 6.35mm.  Accuracy is everything when piecing and the more consistent you can be will ensure a good result. This sounds scary but using Imperial measurements is simply easier.  

Another reason is that a lot of our patterns and products come from America where P&Q is a huge business, considerably larger than that of the UK, or even Europe as a whole.  We do purchase our fabrics by metric, cm and metres, but we then work in inches for the making.

As said earlier, a lot of the patterns we use were originally devised in Imperial.  Let’s look at the traditional Nine Patch block.  A set of nine squares joined together.  Usually one of the first blocks we learn how to make but let’s get to the maths.  

In Imperial, this is easy to change the size of the individual squares to change the block size to make a quilt of any dimension but doing the same in metric is more tricky.

Nine Patch block finished size 9″, unfinished size 9 1/2″ (9 inches plus the two 1/4″ seam allowances). 

In metric this is 228.6mm finished or 241.3mm unfinished.

Let us round up those numbers to make it simpler.  We know that we use a seam allowance of 6.35mm – for ease we can use 6mm as we should use a ‘scant’ but I’ll come to that later.

Our 9” block would be 22.8cm – we’ll round up to 23cm.  Add on the 6mm seam allowance for both sides and you get 24.2cm for the finished block.  

You can see the problem. 

And so inches it is. 

In my next blog, we’ll take a look at the scant seam. I’ll give a few hints and tips on how to get the perfect seam allowance for both machine and hand piecing in our journey to sewing a fine seam.

Until next time,  stay safe and keep quilting.