Lesson video

Hello there, my name is Mrs. Dhami.

Thank you for joining me for your design and technology lesson today.

Now, the big question for today is what are the different options and different choices when we are finishing metals ready to be turned into the final product? There's loads of different choices, so we're going to explore them together.

Hard hats on.

Let's get cracking.

Our outcome for today is we will be able to explain and compare small scale and industrial finishing processes.

We have four keywords for our lesson today: finishing, which is a process that adds surface treatment to improve how a material looks, feels or performs. Aesthetics, which is how the product looks, including color, texture, and style or theme.

Function, which is what a product should do to be successful.

And lastly, surface preparation, which is when you get a material ready for a surface treatment.

We have two learning cycles for our lesson today.

Small scale finishing processes and industrial finishing processes.

So let's get started with small scale finishing processes.

Finishing for many materials is the final stage of manufacture.

However, for metals finishing also happens throughout manufacture.

It serves three main purposes.

Protection, so for example, from moisture or corrosion such as rust, and you can very clearly see the amount of rust on that nut and bolt there.

Aesthetics enhances the appearance of the surface.

So, for example, providing a color on the metal.

And lastly function, so for example, making the surface easier to clean, making it more durable, or perhaps increasing the strength.

And we're going to explore quite a few of these today.

Surface preparation is one of our key words today, and it's what we do to prepare the surface ready for finishing.

So this includes with metals and annealing.

Now annealing is where we heat it to make the metal more malleable for shaping or for embossing, we tend to do this in our school on the brazing half.

Then we have cleaning and decreasing, degreasing rather.

This is where we use chemicals or hot water to remove stubborn residues.

We then have pickling, and I'm gonna talk a little bit more about this later.

This is where we use acid to remove oxides and scale after heating.

So when we anneal something, we then normally pickle it too.

We then have polishing, which is when we smooth the surface and remove scratches.

And lastly, we have rinsing and drying, ensuring the surface is clean and dry before applying the actual finish.

After filing, and wet and dry polishing can create a shiny and smooth final finish.

And we often use a buffer machine with metal.

So a buffer machine is a rotating polishing tool used to quickly smooth and shine the surface of metals.

We also have fine abrasive polishes that can be used to remove any scratches and give a shiny finish.

Now my technician is kindly demonstrating this using a polymer, but the exact same process can be used with metal and it gives a beautiful shiny finish.

Enameling is one of my favorite metal finishing processes.

Basically, enameling melts a thin layer of glass onto the surface of metals such as copper and silver to provide color.

Let's take a little look at how it works.

So first of all, we have to prepare the surface and we use wet and dry to remove grease and fingerprints as well.

We then apply powdered glass to that metal.

Now if you imagine when you were younger and you were using glitter to decorate something, you quite often put something underneath so you could catch that excess glitter.

It's exactly the same with enameling, that powdered glass, if you put a little pot underneath, you can catch the excess and then you can reuse that to enamel something else.

Nice little tip for you there.

You then need to melt the glass.

Now we do that using a jeweler's torch on the braising half, but it can also be done on a kiln, sorry, inside a kiln.

And hopefully you can see in that gif, the tiny bits of glass actually melting.

We then allow it to cool slowly and the enamel hardens into a smooth, glossy finish.

And you can see that blue and green powdered glass creating that beautiful layer.

Definitely one of my favorite techniques.

Patination is a method to change the color of metals like copper, bronze, or brass.

It uses chemicals or natural reactions to make a colored surface that we call a patina.

This alters the aesthetics by creating green, brown, or black finishes and the function by protecting it from corrosion.

And don't those examples look beautiful? If a product has undergone heat treatment such as annealing or enameling finishing is to remove the effects of heat.

So how do we do this? We first of all start off with a warm acidic pickle to remove the dirty oxide layer.

Now if you're looking at that picture and you thinking, is that a slow cooker? You're absolutely right.

It's a mini slow cooker that I have in my workshop, which keeps that acidic pickle nice and warm.

When we are using it to be really effective in removing that dirty oxide layer.

We then get a wire brush, which removes hard to reach areas or very stubborn parts.

Now these are some little copper clay products that some of my students have been making in jewelry club.

They've come out of the pickle and then that wire brush is used particularly in all those small crevices that's really effective.

We then pop them into a tumbler.

Now, again, you might recognize this, if ever you enjoyed finding stones and gems and then popping them in a tumbler to polish them up, it's exactly the same thing.

You pop them in there with what we call a steel shot, which is basically tiny, tiny little circles or tiny little strips of steel, which basically as it rotates round, they bash into the work to help smooth and polish it.

You can also use a polishing powder inside too, or you can pop something like a little bit of washing up liquid too, and that works a treat.

Finally, the final stage is what we call jeweler's wax.

This jeweler's wax polishes, but also provides a protective coat over the top of your metal pieces.

And you can see how shiny those pieces from my jewelry club look in comparison to stage two.

Time for a quick check-in.

Enameling and patination only provide aesthetic benefits to metals.

Is that statement true or is it false? Have a think.

Come back to me when you've got your answer Well done if you worked out that it is false.

And why is that? Enameling and polishing provide aesthetic benefits by changing the color and sometimes the texture.

However, they also provide functional benefits by protecting the metals from corrosion.

Embossing is a small scale finishing process that creates raised or recessed aesthetic designs on a materials surface.

And you can see that in this gif, this is in my workshop.

A stamp here is being used with a hammer to stamp a pattern and a word into that copper.

And this is what it looks like once it has been stamped D & T with a nice little flower.

So stamps can add letters, numbers, logos, and patterns onto metal.

They come in such a wide variety.

Surface preparation.

So what do we need to do before we emboss? Well, actually, we need to anneal, meaning that we need to heat it up to make the metal more malleable so that that stamp goes in a lot more easily.

Embossing can be achieved by using other techniques too.

You can see we're actually making a flower for a flower competition here out of copper.

And it has got lots of different embossing techniques.

So let's take a little look.

That one that I'm pointing out with the arrow that uses metal wire shaped using a pair of pliers to then use to stamp a pattern.

Now you can see in that little gif, I've got some sticky tape that I've put over that piece of bent wire before I hammer it, so to keep it in place.

Now, normally you use something like masking tape, but I use sticky tape so you could see through it and see it for the purpose of today, there is also the technique called chasing.

Now have a little look at the one that it's pointing out from with the chasing.

Chasing is basically when we use a hammer to keep tapping on it, make sure there's metal underneath.

Don't do this with wood underneath, otherwise, you'll completely bend the whole shape out of the shape that it's meant to be.

And that adds little, almost like little domes along the surface.

It's great because it hides not only scratches and fingerprints, but it also creates a beautiful pattern too.

Embossing can also be achieved using a rolling mill with a variety of textures such as lace to enhance the aesthetics.

So how does this work? First of all, you need a piece of annealed metal, and I have got a piece of annealed copper here.

You then need to get something such as the netting that I'm using here, or lace, or ribbon that has got a texture in it.

You can also use dried leaves as well.

You know when they become like the skeleton with the skeleton pattern, they work really nicely.

You pop that on, you pop it between a piece of paper just to hold it in place, and then you pass it through the rolling mill and you need to make sure that you use the gears so you roll it through with a bit of force.

If it's too easy to roll, it won't imprint nicely.

So the force is applied by passing through the rolling mill, and then that leaves a beautiful embossed piece of metal at the end.

A great way to add a surface pattern as a finishing technique.

Powder coating can be used in schools, and I'm gonna talk about powder coating in industrial methods in our next learning cycle.

But for now, powder coating can also be done in schools in small scale finishing processes.

How it works is you need a powder coating box, just like the one in the bottom left of that picture.

You then need to degrease the metal and you need to heat it.

Now we do this on the brazen half.

You then get a massive pair of tongs and dip it into a polymer powder, which sticks because the metal is hot.

After dipping, the piece may be needed to be heated a little bit more to fully melt the powder, which then forms a smooth color, which is of course aesthetics.

But it also provides a rust resistant hard coating, which of course is great for function.

And you can see that is a powder coated product made at my school.

Bluing is a way to protect steel and give it a blue/black color.

It works by chemically oxidizing the metal surface to form a thin protective layer.

This finish is often used on wax tools, firearms and decorative metal work, and helps the function by preventing rust, especially when combined with oil or wax.

Time for a quick check-in, I would like you to match the process to its definition.

So let's start with the definitions.

A, we have protect steel given a blue/black color.

B, creates a green/blue surface color.

C, melts a layer of powdered glass.

D, creates a raised or indented pattern or lettering, or E, creates a smooth colored rust resistant coating.

And I want you to match one of these to one of the processes.

So for the processes we have: number one, patination; number two, enameling; three, bluing; four, powder coating; and five, embossing.

Have a go at matching them up.

Pause the video and come back to me when you've worked out which one matches which.

Okay, well done with all of your matching.

Let's match them up then.

So A matches to three.

So bluing protects steel giving a blue/black color B matches one patination.

Creates a green/ blue surface color.

C, matches two.

Enameling melts a layer of powdered glass.

D matches five, which is embossing.

Embossing creates a raised or indented pattern or lettering.

E matches with four powder coating.

Powder coating creates a smooth colored, rust resistant coating.

Well done with all your hard work on that.

Metals can be painted, however, surface preparation is really important to avoid the paint peeling or flaking.

So what do we need to do? We need to clean the metal to remove the dust grease or oils, we need to sand it lightly to create a surface the paint can grip.

We normally use a little bit of emery cloth to create that slightly rough surface.

We then need to prime it with a metal compatible primer for better adhesion.

And we also need to make sure we use a spraying booth to remove the harmful fumes.

And you might have one that looks a little bit like this in your classroom.

That's the one in my workshop.

If you are using a spraying booth, don't forget to turn it on.

It has to be plugged in and turned on.

When finishing metals, it is always important to consider the following health and safety aspects.

Ventilation, some finishes, release fumes called VOCs, which stand for volatile organic compounds.

PPE, which stands for personal protective equipment.

That includes things such as gloves, goggles, or masks.

And then storage, some finishes are flammable and require adequate storage, and there will be a special place where these finishes need to be stored when not in use in your school.

Time for a quick check-in, what does PPE stand for? Is it A personalized protective equipment? B, personal protective equipment.

C, preventative protective equipment, or D, personal preventive equipment.

Wow, that was a mouthful.

Have a think.

Come back to me when you have made your decision.

Well done if you got B, PPE stands for personal protective equipment.

Onto task A.

Part one, I'd like you to explain one reason why a metal may need to be degreased before finishing.

Part two, explain the process of finishing a metal after a heat treatment such as annealing.

Part three, a student wants to add color to a copper pendant that he has made.

Recommend a suitable finish and justify your choice.

And lastly, part four, describe one method of applying a metal finish and explain one health and safety consideration for this method.

Good luck with your answers.

Don't be afraid to go back through the slides and come back to me when you've made some great answers and decisions.

Part one, I asked you to explain one reason why a metal may need to be degreased before finishing.

You might have said degreasing is surface preparation to remove oil, dirt, and grease so the finish can stick properly and will last without the chance of peeling.

Part two, I asked you to explain the process of finishing a metal after a heat treatment such as annealing.

You might have said, number one, a warm acid pickle to remove oxides.

Do you remember the slow cooker? Then number two, metal brush can remove any hard to reach areas.

Three, a tumbler for polishing.

And lastly, jewelers wax to protect and shine.

Part three, a student wants to add color to a copper pendant that he has made.

Recommend a suitable finish and justify your choice.

You might have said enameling is suitable as it adds color to copper and gives a hard protective finish.

Part four, I asked you to describe one method of applying a metal finish and explain one health and safety consideration for this method.

You might have said one method is spray paint.

Spray paints can produce harmful fumes using an extraction booth and PPE can provide protection for the person applying the finish.

Well done with all your hard work on these answers.

Onto learning cycle two, industrial finishing processes.

Industrial finishing is the large scale application of finishes to metal products during mass production.

These processes are often automated and are designed for high speed and volume, quality and consistency.

Cost-effectiveness by reducing human labor and industrial processes are efficient, but they tend to be less flexible than hand finishing.

In industry, finishing is integrated into the production line using conveyor systems. So items move through each finishing stage such as cleaning and inspecting the product.

Automated machinery, automated machinery is programmed to complete a repetitive task and ensure consistency in application such as coating machines that apply layers of coatings to improve various qualities.

And curing UV or heat curing chambers, dry finishes quickly and often lead to.

Automation in industrial finishing ensures consistency, so quality across hundreds of thousands of units speed, multiple items finished in seconds.

Precision such as robotic arms apply uniform coats so they all look exactly the same, and waste reduction.

So for example, controlled spraying reduces over spray, so less chemicals are wasted or less chemicals go into the environment too.

Time for a quick check-in.

What is one main benefit of using automated machinery in metal finishing? Is it A, they apply finishes with consistent quality.

B, they apply finishes slower than by hand.

C, they make metals more durable, or D, they reduce the cost of raw materials.

Have a read through again, make your decision, and come back to me when you've got an answer.

Well done if you've got A.

One main benefit of using automated machinery in metal finishing is that it applies finishes with consistent quality.

Electroplating is a metal finishing process that adds a thin layer of metal such as gold, nickel, or chromium onto another metal by electricity.

So basically a thin layer of gold in this diagram plates the outside of another metal.

So you can see that layer of gold going off and going on to the other metal.

It's plating the other metal.

It improves the aesthetics and function by protecting it from rust and wear.

Electroplating is often used on jewelry, car parts, electronics and cutlery.

Dip coating is exactly what it says on the tin.

It's when you get a metal object and you dip it into a liquid like paint polymer or lacquer to cover and coat its surface.

The coating sticks to the metal, protecting it from rust and wear, function or improving the aesthetics.

And here is my refillable mug that has been dip coated.

It's after news on tools, hardware, car parts, and decorative items. And the layers of thickness can be controlled by how fast you pull it in and out and how many times you dip it too.

Industrial powder coating is an electrostatic process, so a dry colored powder is electrically charged and sprayed onto degreased grounded metal, so it sticks evenly.

Let's take a little closer look at that diagram.

Can you see the colored powder, so the plain pink dots going up through that spray gun? They are then electrically charged, so you can see then they have a little plus inside that pink circle.

They are the electrically charged color powder that is sprayed onto the degreased grounded metal, so it sticks evenly.

The next stage.

The metal is then heated, which melts that powder that stuck to it into a hard smooth coating.

This protects the metal from rust and wear and is used on things such as bikes, car parks.

Car parks? Car parts, appliances, and outdoor furniture.

Brushing metal is when an abrasive brush is rubbed across the surface to make it smooth, but also to give it a matte textured look.

If you look really closely at that picture on the right, you'll see that matte textured look on that metal.

It actually hides small scratches within that texture and it creates a decorative grain, which, of course, is the aesthetics part.

This is often done on stainless steel, aluminum, and metal furniture to not only make it look nice, but to also hide any fingerprints or scratches, which makes it easier to keep clean and make it easier to keep it looking fresh and new.

Anodizing is a process commonly used with aluminum.

The material is dipped in acid whilst electricity passes through it.

This builds a layer of hard aluminum oxide, which is scratch resistant, ties into function.

Dyes can also be used to add the color, which again provides the aesthetics.

It is often used on window frames, bike parts, kitchenware, and electronic cases such as laptops.

Galvanizing is a metal finishing process where steel or iron is coated with a thin layer of zinc, usually by hot dipping or electroplating.

Let's take a closer look.

So the metal is hanging from the top on that little hook.

First of all, it is degreased.

It's then rinsed.

It's then pickled in an acid.

It's then popped into flux to stop it oxidizing, and then it's popped into the zinc bath where it gains that thin layer of zinc.

And, lastly, it is cooled and it is inspected for any imperfections.

Galvanizing provides strong corrosion protection as the zinc acts as a barrier and sacrificial coating.

Common uses include structural parts needing long-term protection, such as buckets or industrial fencing.

Time for a check-in.

I'd like you to match the process to its definition.

So let's start with the definitions.

A, we have using electricity to deposit a thin metal layer on another.

B, coating metal with zinc to prevent rust.

C, thickening, aluminum oxide layer for protection and color.

D, rubbing metal with an abrasive to create a textured finish.

And for the processes we have: number one, galvanizing; number two, anodizing; Number three, electroplating; and number four, brushing.

Have a think.

Start matching them up.

Come back to me when you've got your answers.

Welcome back, folks.

We have A matching with three electroplating.

Electroplating is when we use electricity to deposit a thin metal layer on another.

B matches, one which is galvanizing, which is coating metal with zinc to prevent rust.

C, matches with two, which is anodizing.

Anodizing produces a thick aluminum oxide layer for protection and color.

And lastly, we have D, which matches with four, brushing.

Brushing is when we rub metal with an abrasive to create a textured finish.

Well done with your hard work on that.

Health and safety is an important consideration in industry so that workers are protected.

Measures include extractors, ventilation systems for VOC control and PPE for human workers in manual finishing stations.

PPE includes things such as respirators, gloves, and overalls.

Manufacturers need to consider the impact that producing products in volume has on the environment.

Considerations include VOCs, which stand for volatile or organic compounds.

These can be found in solvents which can cause air pollution.

Therefore the use of water-based or low VOC alternatives is increasing.

Some finishes have chemicals that can pollute waterways such as waste paints, dyes, inks, etcetera, and wash off water must be treated before being released into the water system.

What does VOC stand for and why is it a concern in metal finishing? Is it A, it stands for very old coating.

It reduces quality.

B, volatile organic compound can be harmful to health and the environment.

C, vacuum over coating used for sanding or D, varnish oil composite creates a strong seal.

Have a think.

Come back to me when you've made your decision.

Well done, if you've got B, VOC stands for volatile organic compound.

It can be harmful to health and the environment.

Onto task B, part one, a copper jewelry ring has been electroplated.

Explain why this finishing process may be suitable.

Part two compared two advantages of industrial finishing over small scale finishing.

Part three, a company wants to finish a thousand car bumpers.

Which process should they use and why? And, lastly, part four, explain one environmental consideration that manufacturers must take into account when finishing metal products on an industrial scale? Good luck with your answers.

Give a good go and come back to me when you are happy.

Part one, I asked you a copper jewelry ring has been electroplated.

Explain why this finishing process may be suitable.

You might have said a copper jewelry ring may be electroplated with gold because it adds a shiny decorative finish that appears more expensive than it is, was protecting the metal from corrosion and wear.

Number two, compare two advantages of industrial finishing over small scale finishing.

Industrial finishing is much faster, allowing thousands of units to be processed per day.

It also offers more consistent results because machines apply the finish evenly every time.

In contrast, hand finishing can vary depending on the person applying it and often takes more time.

Part three, a company wants to finish a thousand car bumpers, which process should they use and why? You could have said powder coating is ideal for industrial scale production because it finishes many bumpers quickly and evenly.

It also provides corrosion resistance and a smooth colored surface suitable for cars.

Part four, explain one environmental consideration that manufacturers must take into account when finishing metal products on an industrial scale.

You might have said waste material like leftover finishes and cleaning solvents are disposed of responsibly.

These must be treated properly to avoid contaminating water supplies or harming ecosystems. Well done with your beautiful efforts with these questions.

This brings us to the end of our lesson today.

Let's summarize what we have found out.

Finishing improves metals, aesthetics, and function.

Small scale methods are flexible for custom work such as enameling and patination.

Industrial finishing uses machines for speed, consistency, and higher volume production, such as galvanizing and electroplating.

Both must consider health and safety, and environmental issues like VOCs.

Well done with all of your hard work today.

I hope you enjoyed the lesson, and I hope to see you in another one soon.

Take good care.

Bye bye bye.