Seams – How to Sew a Plain and Open Seam
Seams are an important part of sewing. You can learn how to sew a plain and open seam on your sewing machine with this quick and easy sewing tutorial. If you are a beginner, learning how to sew, these simple seams are a great place to start.
Seams are essential to construct any type of sewing project from homewares to clothing.
Garments are made by sewing two or more pieces of fabric together to make seams, it just depends on what type of seam you use.
There are heaps of different seam techniques like french, felted, and bound seams but we will just focus on a basic plain and open seam in this tutorial.
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What is a Seam?
A seam is where two or more pieces of fabric are joined together by stitches that are either hand sewn, or machine sewn.
I personally prefer to sew on a sewing machine over hand sewing because I have limited time.
Seams are sewn by following a seam allowance on a sewing pattern, which helps you know the fit of your garment is going to be correct.
I think that the best thing you can do is start practising sewing straight lines on small scraps of fabric until you feel confident.
Then you can move on to practising sewing seams until you feel confident to try a beginner sewing project like our Camille top.
What is the Difference Between Seams and Stitches?
This question seems to come up a lot with beginner sewers and I think it’s a fair one to ask because it can be confusing.
- A stitch is the name of two threads looping through the fabric and a row of stitches can be sewn by hand or on a sewing machine.
- A seam is when two pieces of fabric are sewn together with stitches.
What is a seam allowance?
When you start following sewing patterns you will notice that the instructions refer to following the seam allowance.
The seam allowance is the distance between the raw edge of the fabric to where the line of stitching is sewn.
Basically the extra fabric around the edge of a sewing pattern.
The seam allowance is used to identify the seam lines without there being visible lines to sew along.
Instead, you are given a measurement like 1cm. This distance is measured from the cut edges of the fabric to where the sewing machine will sew seam lines.
For example, if your sewing pattern says the seam allowance is 1cm wide you will need to sew 1cm in from the raw or cut edge of the fabric.
The seam allowance is important because it will determine how the final garment will fit you.
You can learn more about seam allowances here.
What are a Plain Seam and Open Seam?
Now let’s talk about two types of basic seams. There is a plain seam, which is sewn and pressed to one side, and an open seam, which is sewn and then pressed open.
I personally think they are both used much as each other depending on what type of project you are making.
Common places a plain seam is used:
- Attaching sleeves to armholes
- Attaching collars to necklines
- Side seams on blouses
- Sewing a waistband onto pants or a skirt
- Attaching a skirt to a dress bodice
- Attaching a facing
Common places an open seam is used:
- Pant sides seams
- Side seams on a skirt or blouse
- Tailored garments as they are often lined
- Garments made using heavy-weight fabrics to help reduce seam bulk
Both seams can be used in lots of areas on a garment it really depends on how you want the finished result to be.
If the pattern says something like ‘neaten seam and press towards the back this is telling you to sew a plain seam that is pressed towards the back of the garment.
How to Finish Seams
Now let’s quickly chat about seam finishings. This is how the raw or cut edges of the fabric will be finished to stop them from fraying.
If you are sewing a plain seam where both layers of fabric are joined together then this step would be completed after the seam is sewn.
If you are sewing an open seam, it can be easier to finish the edges before sewing the seam together.
There are many types of finishing methods but let’s just look at 3 simple ones:
- Zigzag stitching
- Overlocking on a serger or sewing machine.
- Pinking shears
I personally use an overlocker also known as a serger to finish my seam edges. This is a separate machine that you will need to buy unless you have a sewing machine that does the overlocking stitch.
The sewing machine that I am using is a Bernette B38 by Bernina which has an overlocking stitch setting. It’s really good so if you want to purchase one machine instead of two consider this one!
If you haven’t purchased your sewing kit yet, you can check out my post dedicated to what sewing equipment to buy as a beginner. It shares the bare basics required and a few extras that will help you on your sewing journey.
If you are just practising seams grab some scrap fabric and cut a few pairs of 15x15cm squares.
How to Sew a Plain and Open Seam
Step 1: Thread your Sewing Machine.
Your sewing machine will need to be threaded up correctly before starting. If you need help with this read through these blog posts on how to thread up your sewing machine and how to wind your bobbin first.
Step 2. Change the Settings
Once your machine is ready to go you need to check it is on the right setting. Set the stitching to straight and the length to 2.4 long. This means you can sew a straight line and each stitch will be sewn at 2.4mm long. This is a standard setting for sewing straight seams on a garment.
Step 3. Assemble Fabric to Sew
Place two pieces of fabric together with the right sides facing each other.
Pin along the edges to hold them in place as you sew. You can pin two ways, either sideways to sew over the pins or straight with the ball ends facing you to pull them out as you sew.
Step 4. Lift Foot Pedal
Place the foot lever up and make sure your needle is also up.
Step 5. Hold Threads in Place
Pull the threads to the back of the sewing machine underneath the presser foot.
Popping the threads to the back will help stop them from getting tangled on the bottom of the fabric. This can look messy and sometimes cause sewing problems.
Tip: You can hold the threads as you start to sew. Every sewing machine performs differently so it just depends if your machine will still pull the threads into a knot.
Step 6. Check Seam Width
If you are following a sewing pattern check what the seam allowance is in the pattern instructions.
On the arm of the sewing machine are markings like 5mm, 10mm, 15mm, 20mm and so on. These lines are measured from the needlepoint so you can easily sew the right seam allowances. This means you don’t need to measure or mark the seam allowance when you are sewing.
Tip: You can use washi tape to mark seam allowances on the sewing machine if yours doesn’t have the seam allowance you need.
Place the edge of your fabric along the 1.5cm line for this practice. If you are following a pattern follow the seam allowance from that instead.
Step 7. Place Presser Foot Down
Pop the presser foot down to hold the fabric in place.
Step 8. Backstitch Seam & Sew Seam
Start to sew 4-5 stitches by putting your foot down on the foot pedal. Stop and reverse the stitches so you go back over the stitches you just sewed.
There is usually a reverse button on the front of the sewing machine that will sew a backstitch.
Continue to sew the seam making sure to guide it along the seam allowance line.
Tip: Don’t pull the fabric through as this will break the needle. Just lightly hold the fabric with the tips of your fingers.
Step 9. BackStitch End of Seam
Once you get to the end stop just before the edge of the fabric, about 5mm. Backstitch by reverse stitching a few stitches as you did at the start.
Step 10. Remove the Fabric
If the needle is still down use the flywheel to lift it up. Lift the foot pedal and pull your work out from the machine.
I like to pull my work out towards the back of the sewing machine so the threads release easier.
Cut off the threads to detach your sewing or use the automatic cutter.
Step 11. Finish the Seam
Plain Seam: To finish the plain seam, neaten the raw edges together and press to one side.
Open Seam: To create an open seam follow the same steps as above but before you start sewing you need to neaten the raw edges with your serger or zigzag stitch.
Below is an example of an open seam from my DIY Wrap Dress sewing tutorial. This is a great example of why you might use an open seam on the side of a dress.
As you can see there is a small opening in the seam, it looks like a hole but this isn’t a mistake! The dress is a wrap-around style so this open seam allows for a small opening to be used to pull the tie through.
You have now completed sewing two types of simple seams. Keep practising until you feel comfortable with controlling your fabric on the sewing machine.
Once you start to feel comfortable sewing seams you can try some of my quick sewing project ideas.
Beginner Sewing Project Ideas
- How To Make A Tiered Maxi Dress
- How To Make A Wrap Skirt
- DIY Peplum Cami Top
- DIY Shirred Puff Sleeve Dress
- How To Make A Puff Sleeve Top
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