Lesson video

Hello, thank you for joining me for your design and technology lesson.

My name is Mrs. Conway and I will be guiding you through your learning today.

So today's lesson outcome is I can explain various mechanical and chemical methods to join different materials.

And these are our keywords.

We have mechanical fixings, chemical joining and component.

We'll go through each one of these in turn as we work through the lesson.

So the first thing we're going to look at then are mechanical fixings.

Now mechanical fixings are physical methods of joining materials or components together without using heat or chemicals.

In textiles, they are used to secure fabric parts or attach components.

Now a component is a ready-made part used across different products to make manufacturing easier, such as fasteners and also decorations.

Mechanical fixings are commonly used in fashion, interiors, and also accessories and they can be semi-permanent allowing for maintenance or reuse.

Semi-permanent mechanical fixings are useful because they are easy to apply or remove.

They also allow flexibility in design.

Now sewing is a semi-permanent mechanical fixing as it forms a strong join, but it can be removed without damaging the material and this makes alterations possible.

Quick check for understanding on those points then.

Which of the following is a mechanical fixing? A, fabric glue, B, fusible webbing, C, press stud, or D, sewing? Pause the video here just to take a moment to think about your answer.

And there are two possible correct answers here.

You have C press stud and also D sewing as examples of a mechanical fixing.

Now sewing is mechanical fixing and it's usually done on a sewing machine.

There are different settings and parts that can be used depending on the fabric type and the required finish.

Most machines have these labeled features though appearance and location will vary depending on the make and the model of the sewing machine.

And you may have seen that if you've got several different sewing machines in your classroom or at home for example.

Typically though you have things such as the stitch width, length and type, that can be changed using the controls shown.

Also, you can control things such as the tension and the needle can be changed for thin or thick fabrics.

You can also change the presser foot depending on the finish, such as buttonholes.

Now a sewing machine uses a needle and two threads to make stitches.

It locks the threads together through the fabric while feeding the fabric forward automatically.

And you can see that really clearly in that diagram.

The top thread goes into the fabric.

Then the bobbin, which is underneath gives the bottom thread.

The shuttle hook catches the top thread and the top thread and bobbin are looped together.

The feed dogs, which are the teeth, move the fabric for the next stitch.

Overlocking uses multiple threads to seam, trim and finish fabric edges in one go and overlocking strengthens the seam and stops fabrics from fraying or unraveling.

Here's an example of an overlocker and this is doing an overlocking of a garment.

And here's an example a little bit more closely to see an overlocked edge.

Okay, so what is the purpose of overlocking? Is it A, to glue fabric edges, B, to finish edges and prevent fraying, C, to fuse layers using heat, or D, to chemically bond fabrics? Pause the video just to take a moment to think about your answer.

And the correct answer it was B.

So the purpose of overlocking is to finish edges and prevent fraying.

Well done if you got that right.

A seam is the line where two or more layers of fabric are stitched together.

Seams are essential for shaping and constructing textile products and they are one of the most common mechanical fixings in textiles.

Seam allowance is the area between the fabric edge and the stitching line, and this allows for the sewing adjustment and strength in the final product.

It can also prevent fraying if it's finished properly.

You can see in the image there the seam allowance.

The seam allowance is usually 1.

5 centimeters for most garments or one centimeter for enclosed seams. There are many different types of seams used depending on the fabric type, the product function and the appearance needed as well.

A plain seam is the most basic and used in most garments and it is just two fabric edges sewn together.

You place the right sides of fabric together and sew with a 1.

5 centimeter seam allowance.

Hopefully you can see you have the wrong side and the bright side there shown in the diagram.

Once it's then opened up, you can then press the seam from both sides.

A French seam is a clean enclosed seam with no visible raw edges that is normally used for lightweight fabrics.

Let's look at the process for this then.

You place the wrong sides of fabric together and sew with a 1.

5 centimeter seam allowance.

You then trim roughly half the width of the seam allowance.

You then fold the fabric with the right sides together and stitch to enclose the raw edges.

And lastly, once again, you open and press the seam flat.

A flat-felled seam is a very strong and commonly used in jeans and also outerwear.

So you place the wrong sides of fabric together and sew with a 1.

5 centimeter seam allowance.

You then unfold the seam and press open.

You then on one side of the seam allowance trim just over half the fabric width.

You then on the other side of the seam allowance, fold it in half.

Once you folded it in half, you then fold the side from step four over the trimmed seam allowance.

And then you stitch as close to the edge as possible.

Okay, quick check for understanding on that.

Which seam type is most suitable for sheer, lightweight fabrics like chiffon.

A, a plain seam, B, a French seam, or C, a flat-felled seam? Pause the video here just to think about your answer.

And the correct answer was a French seam.

Well done if you got that right.

Now, fasteners are small components added to textiles to allow garments or products to open and close.

They are removable mechanical fixings that vary in application and also strength.

So an example of one would be a zip.

Zips use a slider to open and interlock teeth, which are ideal for bags and jackets.

And buttons, buttons are made in different shapes, sizes and materials, and they're fastened with a buttonhole or a loop.

You can also have press studs.

They're also called snap fasteners sometimes and they are easy to operate and often found in baby clothing.

And then you have a hook and eye.

Now these are tiny metal loops which are ideal for a concealed fastening.

Quick check for understanding again then.

Which of the following statements best describes fasteners in textiles? A, small, removable components used to open and close textile products.

B, permanent glue-based bonds used to join fabrics.

C, tools used to measure and cut fabric, and D decorative patterns sewn into fabric for style only.

Pause the video here just to reread those answers and work out which one's the correct one.

And the correct answer was A.

So this fasteners in textiles are small, removable components used to open and close textile products.

Some mechanical fixing in textiles are hardware-based and they're often used in bags, belts, shoes and denim.

And these include rivets.

Rivets reinforce high stress areas such as jean pockets.

Also eyelets, eyelets prevent fraying in fabric holes such as shoelace holes.

And also interscrews, and interscrews hold together thick fabrics such as leather.

Hook and loop fasteners consist of two fabric strips.

One side has tiny hooks and the other side has soft loops.

And you can hopefully see that with the closeup of that.

Now when pressed together, they grip securely but they can be pulled apart easily.

And these mechanical fixings are common in products that require an adjustable fit such as shoes and also medical equipment.

Hopefully you can see there the soft loops and also the tiny little hooks on the other strip of material.

Okay, hook and loop fasteners are commonly used because they are A, permanently bonded, B, adjustable and easy to open, C, heat-activated, or D, glued on.

Pause the video just to take a moment to think about your answer.

And the correct answer was B.

Hook and loop fasteners are commonly used because they are adjustable and easy to open.

Now there are benefits and limitations of mechanical fixings.

The benefits are they are easy to remove or replace such as buttons.

They are suitable for most fabric types and they are strong and durable joins.

The limitations however, are they do require tools and a skill such as sewing.

They can add bulk to lightweight garments and they are slower than chemical methods.

Okay, it's going to be over to you now to have a go at a few tasks.

The first thing I'd like you to do is define the term mechanical fixing in the context of textiles.

Then I'd like you to compare a press stud and an interscrew as a mechanical fixing.

Next I'd like you to give two reasons why a designer might choose hook and loop over buttons in a children's jacket.

And then lastly, I'd like you to explain why a designer might choose a flat-felled seam instead of a plain seam when designing denim jeans.

Pause the video here to have a go at these four tasks and good luck.

Let's have a look at each one of these then.

First thing I asked you to do was to define the term mechanical fixing in the context of textiles.

The example answer reads, "A mechanical fixing is a physical method used to join textile materials without using heat or chemicals.

Examples include zips, buttons, and sewing." I then asked you to compare a press stud and an interscrew as a mechanical fixing.

The example answer reads, "A press stud is a small fastener that snaps two fabric parts together and is often used in clothing.

An interscrew consists of two metal parts that screw together, commonly used in leather goods.

Press studs are easy to open and close while interscrews are more secure." Your answers are going to be slightly different to these.

That's absolutely fine.

Just compare yours to these and make sure that you've got the key parts of the answer.

Next, I ask you to give two reasons why a designer might choose hook and loop over buttons in a children's jacket.

Hook and loop is quicker to fasten and safer for children as it reduces choking hazards and is easier for small hands to use.

And lastly, I asked you to explain why a designer might choose a flat-felled seam instead of a plain seam when designing denim jeans.

And the example answer reads, "A flat-felled seam is strong and wear-resistant, making it ideal for denim jeans.

It hides raw edges to prevent fraying and gives a neat, professional finish.

A plain seam is weaker and may leave edges exposed.

Once again, just compare your answers to these model answers and check you've got the key points included in yours.

Next we're going to look at chemical joining.

Now, chemical joining is the process of bonding fabrics or components using adhesives or heat-activated materials.

It does not involve stitching or physical fixings, which makes it useful for lightweight, delicate, or synthetic fabrics where sewing might damage the material.

Chemical joining is used for various reasons, such as to reduce bulk, for a smooth, seamless finish, to speed up production.

Also, ease of repair and applying embellishments.

Here's some examples.

Fabric glue provides a no-sew approach for crafts and doing things such as altering hemlines.

Which of the following is an example of chemical joining? A, a zip, B, a press stud, C, overlocking, or D, bonding tape? Pause the video here just take a moment to think about your answer.

And the correct answer it was bonding tape.

That is an example of chemical joining.

Well done if you got that right.

Now, heat bonding uses fusible webbing or fusible tape.

Materials with heat-activated adhesive, which then sets permanently.

Heat, usually from an iron, is applied and the adhesive melts and then bonds the fabrics together.

Fusible webbing is normally used for things such as name labels, hemming tape, and also applique patches.

So here's an example of iron-on applique patches, which are quick and an easy way to customize garments.

PVC, which is polyvinyl chloride, is a synthetic polymer used in items like waterproof clothing and inflatables.

When damaged, it can be repaired using chemical adhesives designed specifically for plastics.

The applications can include repairing punches and fixing seams and also reinforcing fabric edges.

So punctures in inflatables such as swimming arm bands can be repaired easily.

Okay, quick check for understanding then.

What does the abbreviation PVC stand for? Is it A, polyvinyl carbonate, B, plastic vinyl compound, C, polyvinyl chloride, or D, polymerized vinyl cloth? Pause the video here just take a moment to think about your answer.

And the correct answer was C.

PVC stands for polyvinyl chloride.

Welding is a thermal joining process used to bond synthetic fabrics like PVC or polyurethane.

It involves applying heat and pressure to melt the surfaces of the materials which then fuse together as they cool.

Unlike adhesives, welding forms a seamless and extremely strong bond, which is ideal for heavy-duty or waterproof products.

So here's some examples of some pool inflatables.

The welding forms a really airtight seal, which is essential for this product.

Hot air welding is able to create strong joins between synthetic fabric layers and curves can be bonded easily using this process.

The diagram on the right shows a transparent PVC layer being bonded to a solid gray layer.

So a nozzle blasts heated hot air between the layers and the layers soften.

It is then moldable.

It is then in a moldable state and rollers fuse the two materials together.

High frequency welding uses radio waves between metal plates to create heat and fuse PVC together.

It is a fast process making it suitable for higher volume production.

And high frequency welding works well on thicker materials and provides a really clean finish.

If we have a look at the example then.

There are two layers of PVC that are placed on the bed.

The radio waves heat and melt the PVC along a straight edge.

And then the PVC is bonded along a straight seam.

Right quick check for understanding on that then.

Which of the following is a benefit of PVC welding? Is it A, creates a strong waterproof seam, B, uses thread and needle, C, temporary join that's easy to remove, or D, requires no heat or tools? Pause the video here just take a moment to think about your answer.

And the correct answer was A.

So a benefit of PVC welding is that it creates a strong, waterproof seam.

Now there are benefits and limitations of chemical joining.

The benefits are no stitching is needed.

You can get a smooth finish and they can be quick to apply.

The limitations however, are that they can weaken in wash cycles, they're not suitable for heavy fabrics, and they are harder to adjust once bonded.

It's going to be over to you now to have a go at some more tasks.

So the first thing I'd like you to do is to define the term chemical joining in textiles.

I'd then like you to give two reasons why bonding tape might be chosen over sewing in garment production.

I'd then like you to explain one disadvantage of using fabric glue to attach components.

And lastly, I'd like you to explain why a designer might choose PVC welding instead of stitching or adhesives when joining PVC-coated fabrics for outdoor products.

Okay, pause the video here to have a go at all of these four tasks and good luck.

All right, how did you get on? Let's take each one of those in turn.

So the first thing I asked you to do was to define the term chemical joining in textiles.

Here's an example answer for you.

Chemical joining is bonding fabric or components using glue, tape, or heat-activated materials instead of stitching.

The next question then was to give two reasons why bonding tape might be chosen over sewing in garment production.

Here's an example answer.

Bonding tape is quicker to apply and creates a smooth, seamless finish without visible stitching.

Just compare your answers to these.

On the second question I've just given you one reason why bonding tape might be chosen.

Did you get another reason included in there as well? Just compare your answers and make sure you've got the key points from those examples.

Next, I asked you to explain one disadvantage of using fabric glue to attach components.

Fabric glue may weaken after washing, meaning the bond might not last as long as a stitched join.

And lastly, I asked you to explain why a designer might choose PVC welding instead of stitching or adhesives when joining PVC-coated fabrics for outdoor products.

Here's an example answer then.

PVC welding creates a strong, waterproof bond by melting and fusing layers together.

It's more durable than stitching, which can leak, and adhesives which may fail in bad weather.

Once again, just compare your answers to the examples and check you've got the key points.

Right, let's summarize today's lesson.

Today we've been looking at joining processes for textiles.

Mechanical fixings join textiles using sewing and components like fasteners, rivets, or hook and loop.

Seams and allowances shape and strengthen stitched textile products.

And chemical joining uses glue, tape, or heat to bond fabrics without stitching.

PVC can be joined with adhesives or welded for strong, waterproof seams. Well done for all of your hard work today.

Thank you so much for joining me, and I will see you soon.