If you are new to sewing you may be wondering what a grainline is…
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What is a grainline?
The grainline is the way that a pattern is cut out when it is laid out on a piece of fabric.
The grainline is often cut along the lengthwise yarns in a piece of fabric. Lengthwise yarns are referred to as weft threads.
When you think of a roll of fabric the weft threads are the ones wrapping around the roll creating the metres of fabric.
Warp threads go across the cross grain of the fabric. Warp threads are shorter making them stronger within the fabric.
When you look at a roll of fabric the selvages are the sides of the cross grain threads. I like to think of the selvages as the uncut edges of the fabric that usually have a border.
Sometimes the selvage has small holes along the edges instead of the white border as seen below.
Another tip to remember what the selvage is to think about a roll of fabric. The roll has two ends. Each end is the selvage of the fabric.
Why is the grainline important?
The grainline is an important term in the sewing world. It helps guide where to place the sewing pattern pieces onto the fabric.
If we didn’t have a grainline then we wouldn’t know how to cut out the garment pieces correctly.
For example, if I was making a bias cut skirt, it would need to be cut on the bias grain.
A general rule to remember is that the grainline is always placed parallel to the fabric selvage.
You can see below in diagram A, that the skirt pattern is laying diagonally to the edge of the fabric but the grainline is kept parallel to the selvage.
A bias skirt is usually cut on the bias grain for fit, shape, and drape purposes.
If I cut this skirt out on the straight grain as diagram B, the fabric wouldn’t have the correct stretch or movement required. This means it won’t fit the size it’s made for.
How do you find the grainline?
If you are using a woven fabric like cotton poplin I like to cut a small slit into the edge and rip the fabric apart.
This will help you find the true grain as the warp threads are straight up and down they rip to the correct grain. The weft threads will rip across. I have shown both below.
This is the way I always find the grainline on my fabrics especially if I don’t have any selvage to guide me. This often occurs when I’m rummaging through my scrap basket.
If the fabric is too delicate to rip like this just cut a slit into the end and try to fray the ends. You should be able to see the grain by pulling at the threads.
How to cut on the grainline correctly?
If I am sewing a project that requires accuracy like a bias cut dress I like to layout my entire piece of fabric.
I then place my pattern pieces on top one by one and measure the same distance from the grainline to the fabric selvage.
To do this you need to make sure the selvage is as straight as you can get it. I like to line my fabric up on the edge of a table and tape it down with masking tape.
I then find the right place on the fabric for each pattern piece. Then I measure from the selvage in to my grainline.
Note the measurement down and check at a few points along each grainline that the measurement is the same distance from the selvage.
This means the pieces will be cut on the same grainline helping get the correct 45-degree bias angle. You can learn how to lay up your fabric and cut out pattern pieces precisely here.
What happens if you cut off grain?
If you cut slightly off the grain its not the end of the world! So don’t panic.
It really depends on the type of garment you are making to how accurate the cutting out needs to be.
When I am sewing myself a little cami I will just line up my grainline by eye. If I am making a silk wedding dress I would measure my grainline to ensure accuracy.
Cutting out a pattern all over the show with no clue where the grainline is scary biz! You will most likely run into some trouble once you begin sewing up your garment.
When you cut pattern pieces the grainline is either cut along the warp or weft threads or the bias grain. Most of the time patterns require the fabric to be cut on the straight grain (warp thread direction).
The bias grain is cut at a 45-degree angle but cutting not on the true bias will cause your pattern pieces to stretch and warp out of shape quickly when sewing.
You will also find that your garment may be twisty and uncomfortable to wear.
futher learning resources
If you are a bit frazzled don’t worry!
When I first started sewing I found these terms to be super confusing. I recommend being hands-on with fabric and patterns to gain a good understanding of the grainline, selvages, and bias grain.
I love to learn from books, which is why I recommend the book How Patterns Work by Assembil.
This book is full of valuable information for sewing and understanding sewing patterns. It’s a real beginner-friendly read that includes clear descriptions and diagrams throughout.
If you are interested in finding more helpful books check out this blog post on books I use and find helpful.