Sew a Fine Seam – The Scant Seam

Welcome to my next instalment of the Sew a Fine Seam series of blogs. 

In my previous Sew a Fine Seam blog I mentioned the ‘scant’ seam.  You will hear this quoted as the only way to get accurately pieced blocks but what exactly does it mean and why? 

When we see a block we would like to make it’s usually drawn or printed on a page of a book or magazine. This is a 2D image which we try and make out of a 3D substance – the fabric.  Fabric has a depth, albeit a tiny one, but we have to accommodate this thickness.  

(As an aside, fabric is graded by weight rather than thickness.  The weight of one square metre of fabric will give you the grade of fabric. The heavier the weight usually means the fabric is thicker. Quilting cottons are usually of a medium weight.)

Once we have joined our seam we need to press the allowance on the back over to one side – ‘the dark side’. (Yes, remember that space film and I’ll cover this in the next blog.)  The folding process reduces the size of the seam allowance by a scant amount, meaning that this will change the actual width of the block. To try and stick to the perfectly drawn 2D image of the quilt block we are trying to create,  we need to allow for this tiny amount and so we sew a scant seam.  Literally a tiny bit towards the raw edge of the seam allowance. 

So, how do we get a good scant seam?  I now introduce the 1/4” foot for your machine or drawing a line to sew along for hand piecing.  Let’s look at these separately.

For machine sewing a quarter inch foot is a handy guide to help BUT these are rarely accurate and they can bend a little too! The best thing to do is to check the seam allowance of your particular foot and, armed with this knowledge, you can change your needle position to make the required adjustment.  If you are unable to move your needle position,  you can adjust where you guide the fabric to make the relevant change.

1/4″ Foot. The guide on the right side sets the distance from the needle.

To check your 1/4” foot take three pieces of accurately cut fabric: 1 1/2″ by 2 1/2″ Rectangles. Sew two of them down their length.  They should finish to make a 2 1/2″ square.  Take the third rectangle and sew it across the top.  It should fit exactly. If not, it will indicate exactly how much your foot it out.

Hand sewing – I do like to mark my seam allowance which is easily done.  You can use your clear rotary ruler which should be marked with the 1/4″ but I find a Quilter’s Rule useful. Not so cumbersome and much cheaper.  They are around £2 and you can get them in both 6″ or 12″ lengths.  They are a 1/4″ square of plastic which you position against the raw edge and draw a line done.  

Drawing the line also needs attention. Use a sharp pencil or marker and make sure the nib sits right up against the ruler.  If you just draw without care you’ll find your line is millimetres away from where it should be and is a common mistake. The advantage to hand sewing is that it is more forgiving. You can make minor adjustments as you go along to ensure those points aren’t lost. 

Another tip is to position your rule with the 1/4” just off the edge, and I mean a tiny amount. Then, when you draw the line, the mark will be precisely at the 1/4 rather than being 1mm to the right of where it should be. 

These little hints and tips can help you improve your piecing and get to grips with the magical world of patchwork and quilting.  Next time we’ll take a look at pressing which can make a world of difference…

Until next time, stay safe and keep quilting!

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