Original subtitles

When life gets hectic, it's really important to relax and unwind.

And one of the best ways to do that is to take a bath.

For me, a bath is a real treat.

There's no end of choice as to what you put in it.

I like a bath bomb.

In the 1990s, fizzy bath bombs exploded onto the market.

Fragrance-filled...

..calming or invigorating...

..they bring a different dimension to bath time.

So, to reveal the secrets, and the science,

behind their colourful contents,

I've come to a factory that's been making them for 27 years!

I'm Gregg Wallace...

Mate!

..and tonight, I'll be adding a bit of sparkle...

Ha-ha! I think I might end up looking like a glam rock guitarist.

..and hand-crafting with colour...

What a lovely job this is.

..to create a kaleidoscopic bath bomb.

Wahey!

I'm Cherry Healey...

Oh, wow.

..and I'm in search of ethical ways to trial our bathroom potions.

So, you make human skin in a lab,

and that's what you test the products on?

Oh, it's horrible.

And historian Ruth Goodman...

Whale regurgitation.

..concocts a death-defying perfume.

And this is going to keep me safe from the plague.

This factory produces 14 million bath bombs every single year.

And I'm going to reveal just how they do it.

Welcome to Inside The Factory.

This is the Lush factory in Dorset.

And it smells amazing!

Here, they make all sorts of colourful cosmetics,

with a passion to manufacture in an eco-friendly way.

665 workers make most of them by hand.

Mate, the colours and the smells.

This is proper nice.

From fancy floral soaps...

..to products for your body and hair.

But...

Personally, I'm not that bothered about shampoo,

but I do enjoy a good bath.

So, today, I'm following production of one of their bestsellers -

the Intergalactic bath bomb.

It may sound out of this world,

but my bath bomb starts life far more down to earth.

at Intake, where I'm meeting Warehouse Manager Chris Smith.

Hello, Chris.

You all right, Gregg? Nice to see you. Good to meet you.

So, making a bath bomb, what do we have to start with?

Right now, we actually have a delivery of sodium bicarbonate,

which is our main ingredient that helps make our bath bombs fizz.

Let's go and see that inside.

The lorry contains six tonnes of sodium bicarbonate,

imported from France.

Enough to make 36,000 bath bombs.

And as the super-sized, one-tonne sacks of powder are unloaded,

my bath bomb production begins.

But before we crack on,

I want to know how this ingredient makes my bath bombs fizz.

So, Gregg, this is our sodium bicarbonate.

Yeah. What exactly is it?

It's just baking soda. And what's the other one?

So, the other one we've got here is citric acid.

When you use baking soda, you need an acid to help it react to

create carbon dioxide. That gives it the rise and the fluff.

In baking, you might use lemon juice. We use citric acid.

When that mixes with water,

it creates carbon dioxide, that gives it that extra fizz.

The procedure that makes my cake rise is the same procedure

that's making your bathwater fizz? It certainly is.

So, here, we have a mix of sodium bicarbonate and citric acid.

If you'd like to pour it into the water.

Whoa!

That certainly fizzes.

What you're teaching me here, my friend, is the biz of fizz.

When mixed with water, the two powders dissolve

and react to form sodium citrate and carbon dioxide.

And it's the emission of this gas, as bubbles, that creates all the fizz.

Thank you very much indeed.

I now know how to make fizz.

You're welcome, Gregg.

It looks fun, but the bubbles also disperse the colour

and scent in the bath.

Sodium bicarbonate has deodorising properties and a softening effect on

hard water, soothing your skin, and creating a super-relaxing bath time.

I do find a good, hot soak is a great way to de-stress

after a long, hard day.

But what is that time in the tub actually doing to our body?

Cherry has been dipping her toe into the science.

Now, I love a relaxing soak, too,

but I've been told that a bath

can also provide some of the benefits of exercise.

Can that really be true?

To find out more, I've come to Loughborough University

to meet Dr Christof Leicht,

who's conducted studies to

investigate how hot baths could help our health.

Hi, Christof. Lovely to meet you. Hi, Cherry.

So, you're saying that hot baths can have health benefits?

So, we've done lots of research in this area.

And, yes, we do get some health benefits by taking hot baths.

There's quite a lot of evidence that when people raise their body

temperature regularly, they get health benefits from that.

It's like all my dreams come true.

But it's not going to be a replacement for exercise.

This could be interesting for people who can't exercise, right?

So, people with a disability or people who are frail,

and for them, it will be useful to have another thing

to do if they can't do exercise.

So, would they get the same thing by having a bath?

Regular exercise strengthens the heart and blood vessels,

improving circulation and lowering resting blood pressure.

Christof wants to show me how blood pressure can also be lowered

with hot bathing, by putting my body to the test.

I am a bit nervous, actually. OK...

First, he measures my blood pressure at rest...

..and my heart rate

to help us compare them later.

OK.

We also need to measure my core body temperature.

And for that, I have to swallow a high-tech thermometer,

hidden inside this pill.

Are you kidding me?!

OK, so, three, two, one.

Down the hatch.

Oh, God. I'm officially a cyborg.

A receiver will read the transmitter through my body.

Let's go. I'm all set for that 30-minute hot bath.

After you. Thank you.

But it's not quite the spa experience I had in mind.

Oh, oh! That is pretty hot.

The bathwater is a steamy 39 degrees Celsius.

Go in.

Oh, my gosh. That is warm.

Two degrees hotter than my usual bathwater at home.

I'm sweating.

I'm really hot and starting to get a bit uncomfortable.

I can feel the heat getting my heart pumping.

So, what is going on in my body right now?

So, your resting heart rate was 62,

and now we're, after ten minutes in the bath only,

it's 75, because all the blood of your body will be directed

to your skin to try and cool the body.

So, it's having to work really hard to get that blood around my body,

so that it can find somewhere to cool off. That's right.

I feel like it's time to measure my little robot friend.

That's right. I'll read it.

So that is 38.13.

Oh. So, you're up by a degree.

One degree doesn't sound much, but, for my core temperature,

it's a big increase that my body is working hard to try to correct.

Let's get your blood pressure, yeah?

So, your blood pressure is now 103 by 50.

So, the lower number has gone down,

and the lower number is

basically a measure for how open your blood vessels are.

So, they're all open now, right?

Your blood rushes to the surface,

and that's quite a decent drop that we find here.

So, my blood vessels have all opened... Yes.

..to let the blood through, to go to my skin... That's right.

..to try and cool it down? That's right.

My blood pressure lowers and my heart rate continues to increase...

106, 107.

108, 109.

..over the course of the 30-minute bath.

Is it time to get out? Let's go. But take it slowly.

Sometimes people feel a bit light-headed.

I do. I actually do feel a bit light-headed.

Whilst I dry off, Dr Christof analyses the data.

What did these results show about what's going on inside my body?

In the bath, basically, that heart rate goes up...

..in order to distribute the blood towards the skin's surface.

And what's quite interesting as well is the blood pressure.

In the bath, that decreases blood pressure

because all your vessels open up.

So, from these results and the research you've done,

what would you say is the overall benefit of having a really hot bath?

I think what your results show, quite nicely, was that

decrease in blood pressure. So if you were to repeat these baths

three times weekly, over six to eight weeks or so,

then even your resting blood pressure could come down.

And that's, in general, a very good thing.

High blood pressure is a risk factor for many

cardiovascular diseases like heart-related issues,

stroke and so on.

Can I swap exercise for hot baths?

A bath doesn't replace exercise.

It may be a very good solution for people who can't exercise,

for whatever reason, for disability, frailty.

But if you can exercise, you should do exercise.

So, hot baths cannot replace exercise,

but they can be quite good for your heart. Absolutely.

But before you run a really hot bath,

make sure it's not over 39 degrees Celsius.

And it's not useful for those with existing low blood pressure,

so check with your GP before you take the plunge.

Here at the factory, I'm hoping to raise the bath-time

heart rate with some fizzy surprises.

One tonne of sodium bicarbonate is locked

and loaded onto a giant hopper...

..in a department they call Ballistics.

So, that's where I'm headed, to prep the explosive

powder for my bath bombs with compounder Paulo Silva.

Mate, you have got a great factory.

I've got the best job in the world. Paolo, good to meet you.

Nice to meet you. What is a good bath bomb?

A good bath bomb is going to lift your spirits,

make you feel happy, joyful. Mate!

That's the most inspirational line I think I've heard in a factory.

Well, I do appreciate that.

So, first, we have to fill our mixer with our main ingredient,

sodium bicarbonate.

Now, I'm going to press a button. Press the button, Paolo.

Press the button.

So, now, vacuum is created and our bicarbonate is coming through

this chute and into our machine.

800kg of sodium bicarbonate enter the mixer.

Enough to make 6,000 bath bombs.

This factory can use up to 67 tonnes every week!

But there's no citric acid for fizz yet.

This is all about creating colour.

Right, it's completely white.

It is. Are we going to add some colour?

Yes, we are.

The factory uses more than 100 unique blends of colour.

My Intergalactic bomb calls for three super-bright pigments.

Blue...

..pink...

..and yellow.

The mixes are all made in separate batches, transforming them

from the snow-white sodium bicarb.

Today, we're going to be doing the blue mix.

So, would you kindly... Take a bucket over.

..bring the bucket into our mixer, please? That's heavy.

This synthetic pigment is similar to food colouring for home baking.

But for bath bombs, it comes by the bucket-load!

Oh! Everything is going from white powder to a turquoise blue.

Yes. And it will just get darker and darker.

Is that right? Yes.

Usually, we wouldn't be using this mixer with a lid open

but, today, we'll make an exception so that you can have a better

understanding of how our ingredients are mixed.

Through the clouds, you can see it turning colour.

Very smart. Very nice.

120cm-long paddles spin at a leisurely

26 rotations a minute to stop clumps forming.

And in just 40 minutes, the dye is fully mixed into the powder.

What's the next big bit?

Fragrance. And for that, you're going to go to the fragrance room

to speak with Emma. Emma in the fragrance room. Yes.

Thank you, Paolo.

To ensure its bath bombs are sweet-smelling as well as colourful,

the factory has its own perfumier, Emma Vincent,

who has an expert nose.

Emma. Hello.

Can you show me what's going to make up the fragrance in my bath bomb?

I can.

So, the recipe is a secret, but we've got four key ingredients here

that make up the majority of your mix. OK.

White grapefruit oil, vetiver oil,

cedarwood oil and peppermint oil.

Tell me, how do you make an essential oil from a grapefruit?

Well, from the grapefruit,

the essential oil exists in the membrane.

So when you're cooking and you zest your grapefruit,

what you can smell is the essential oil.

So, the fragrance of anything is its essential oil?

So, they sort of grate it off and the oil is cold-pressed,

or steam-distilled, and that captures the essential oil

and pulls it out of the plant material.

Basically, you are trapping the natural smell of every ingredient.

Mm-hm. Brilliant.

20 grapefruits go into this one small bottle.

So, we have grapefruit essential oil.

Have a sniff.

Oh. Oh, that's good.

You know what that smells like to me? Clean.

Yes. That's clean. Yes.

Well, it's very cleansing on the skin.

So, that's kind of part of what's in the bath bomb, it is

in the design to cleanse your skin when you're in the bath.

Oh! This is good, this.

Right, what's the next one?

Cedarwood, which actually smells like pencil shavings.

This Cedarwood Virginian is extracted

from the red cedar tree,

native to North America.

Oh, hang on a minute.

That's almost like smoke.

Why do you want that smokiness?

It helps with relaxing your muscles within the bath.

Mint.

Let me tell you, mint, I think, is my favourite, favourite herb.

But there's spearmint, of course, and there's peppermint.

You've got peppermint. Yes.

Mm!

What does mint do for us in the bath, then?

So, it contains menthol.

Sniffing it now, you can see it sort of clears

your airways, so it perks you up and gets all those sensories tingling.

OK. And now we have vetiver.

A bird's nest? Yeah. Enjoy!

SHE LAUGHS

This is actually grown in Indonesia.

It looks like long blades of grass,

but you have to take it out of the ground to get the roots.

And that's where the essential oil is.

Vetiver is similar to better-known fragrant plants lemongrass

and citronella.

Oh!

It's almost a colour in a smell.

It's dark, liquorice, brown.

So it's quite an earthy scent.

It's a warming oil.

It will kind of relax all those muscles when you're in the bath.

Oh, how lovely.

All these essential oils are carefully trialled

and blended by Emma and her team.

Now, what happens when you mix them all together?

We can smell the finished product.

Oh, lovely.

Oh, that's good, that.

This now smells like a luxurious bath. Mm-hm.

I need a large bucket to scent 6,000 bath bombs.

Emma, thank you so much.

That was educational and a great deal of fun.

Take this to the mix? Yes, please.

One hour and ten minutes into production,

our blue bath bomb mix is ready for me to add my exotic aromas.

Paolo! I've got something quite special here.

Oh, that is amazing.

That is a deep, deep blue, isn't it?

It is like a midnight sky blue, I would say. Yeah.

So it is ready for our fragrance. So if you can, please.

Gram for gram, the fragrance is the most expensive part of the mix.

You're a natural, Gregg.

GREGG LAUGHS

And it also has the longest-lasting effect.

When you go home on the bus, do people say you actually smell nice?

Yes, they do.

I get quite a lot of compliments.

Really? Yes, I do.

My bath bomb mix is absolutely full of fragrance,

but Ruth's been investigating a time

when perfume wasn't just about smelling sweet.

Nowadays, a lovely bottle of scent is a simple pleasure,

but here, in Britain, during the 17th century,

perfume was taken deadly seriously.

I'm meeting Professor of Sensory History

at Anglia Ruskin University, Will Tullett, in the beautiful

surroundings of the Chelsea Physic Garden,

founded in 1673.

Aroma's always been important to people, but what is it,

specifically, about the 17th century that makes it draw our attention?

Well, firstly, there is a huge influx of new, fragrant plants

and spices and herbs and aromatics that are coming into England

from the colonies, from trade.

And one of the reasons they are doing that is because they're

having to deal with some big issues, one of which is plague.

Over 300 years, outbreaks of plague ravaged Britain,

from the Black Death in the 1300s

to the Great Plague of London in 1665.

Although we now believe it was spread by fleas,

at the time, this deadly disease was thought to be

transmitted by foul smells.

So, to protect themselves,

people used sweet-smelling herbs to purify the air.

So, I've got rosemary there and lemon balm, and myrtle.

So, these are the sorts of plants that people are turning to.

Particularly in periods of plague,

stuff like rosemary becomes expensive.

It would be six shillings for a tiny handful -

which, in today's money, is about sort of £40, £45.

And so you could wear it in your pocket, in your hair.

This is it, then. I've got my myrtle.

Shove it in my hair. There you go. In the 17th century,

breathing a smell in is basically like eating it.

You're incorporating it into your body.

If you're surrounded by dead carcasses and stagnant

pools of water and faeces, the worry is that all of those horrible,

putrid materials would cause your body to rot as well.

Whereas nice smells, they help the body to fight back

and take the poison of the plague and push it out again.

As well as buying expensive herbs,

the wealthy could afford something rather more fancy.

You might use what's called a pomander,

which is a little ball of perfumed paste, basically.

And we're going to have a go at making one of those now.

Great. So, we've got a recipe here from Sir Hugh Platt,

who was an agriculturalist and inventor, and he published

this book called The Delights For Ladies, which went through...

"Delights For Ladies." Yeah.

So, I'm making a delight for you, Ruth.

Fragrances came from the natural world in various forms.

Our first ingredient is calamus aromaticus,

an exotic powder made from the roots of a fragrant grass common in India.

Oh, now, that's a weird smell.

It's almost like smelly socks.

Next is a blend of resins made from dried tree saps.

They'll kind of form the glue that binds it together.

And now we're moving on to some slightly different ingredients.

We're moving on to the kind of animal ingredients of the recipe.

"Animal ingredients"? Yeah.

Throughout history, perfume makers used the secretions

from animals to produce long-lasting, powerful scents.

Ambergris gave off a musky smell.

It came from the sperm whale,

which expelled it in huge lumps that floated in the ocean.

Our sample has come from the collection of a perfume historian.

In the 17th century, they had no idea what it was.

So, some people thought it was a special mushroom that grew

under the sea, for example.

But, today, we know it comes from whales.

One small lump of whale regurgitation.

And we're also going to put some musk,

which is a glandular secretion.

Our musk is synthetic,

but historically it

came from the Asian musk deer,

and added a leathery, spicy note.

So, in a sense,

it's just the powerfulness of these scents that made them medicinal.

It's not like each individual plant is doing something separate.

It's just like, because they're strong. Yeah.

The ingredients are heated until they combine into a sticky paste.

If you pick a bit of that off and then roll it in your hands,

into a ball. It's warm. It's not hot.

It's not hot. And there we go.

That's it? That's it, essentially.

We've got our pomander.

How would you describe it? What's your best effort?

That is seriously complex, isn't it? Yeah. Yeah.

I... I... Like, pine and...

..strawberry and...

I don't know. There's loads going on.

Pomander balls were often carried in a small, decorative globe.

We'll just pop it in. Put the top on.

And I suppose if you walk, every time you move,

you're going to make it... Exactly. ..bounce about.

So it jogs the scent, releases a bit more from it around you. Yeah.

It sounds so ridiculous, but I can also see why it made sense

to people at the time, when they hadn't got the modern science.

Good smells will drive away infection, keep you safe.

And we shouldn't be too sniffy about these strange early concoctions.

They are, after all,

the origins of today's

multi-billion-pound perfume industry.

Back at this most fragrant of factories,

I'm enjoying the colours and smells of bath bomb production.

After one hour and 20 minutes,

I'm back with Paolo and his perfumed, bright blue mix.

Now we need to add the fun part of it.

So, I would like you to try this one first, please.

Salt? Is it sugar?

That's popping candy. It crackles up and down on your tongue.

It is. Why have you...?

You're not going to put popping candy in it, are you? Yes, we are.

Why? It's just going to make it crackle.

Just a little bit of fun.

So, shall I sling that in there now? Do you feel strong? Yeah.

OK. Good.

Used mostly for sweets,

popping candy is solidified sugar

with carbon dioxide trapped inside.

They get through nearly ten tonnes of the stuff here every year.

It's cracking as it goes in.

It is.

It will crackle much more once you put it in contact with water.

Anything else, Paolo? Yes.

This ingredient. It's a shimmering lustre.

And it's going to look like stars in your bathtub.

What's lustre?

It's a mineral made to replicate glitter, but it's plastic-free.

Lustre is like glitter without plastic?

Exactly. It is the same effect,

but it's much healthier and is much better for nature.

But doesn't it stick to your body? No, it won't.

I'm not going to have a bath, am I,

and come out looking like I've just landed from Mars?

No. As you can see, it's tiny particles.

It will dissipate in the water.

So this lustre will add a little bit of extra sparkle to our mix.

Most certainly will.

I think I might end up looking like a glam rock guitarist.

This might get a bit messy.

Whoa!

I think you're going to be ready to go out.

That's amazing!

Hooray!

GREGG LAUGHS

This gold lustre is a chemically-bonded structure

that includes iron, titanium, and tin oxides,

and will sink as a harmless sediment in water.

Now we just have to close the lid again and wait a little bit,

until the mix is ready.

All that lustre, colour

and scent combines with the fizzy base for five minutes.

Thank you, my friend.

You have covered yourself in stardust.

Thank you so much, Gregg.

After nearly an hour and a half, my blue powder

whizzes down a tube into a big tub...

..ready to be moulded into bath bombs.

But the factory doesn't buy in their moulds.

These clever clogs make them themselves, as sustainably

as possible in the factory's very own moulding department...

..where I'm meeting Moulds Room Manager Patryk Biernat.

Patryk. Hello, Gregg.

I need moulds.

You are in the right place, Gregg. That's what we make today.

So how many moulds will we make today?

Today, we're going to make about 100,000 of these moulds.

Very good. How many times do you use them?

About five times. Then they can break.

So, where is this plastic from?

Recycled plastic.

All our waste, broken moulds - recycled.

You make your new moulds out of old moulds?

Exactly.

We shred them, process, back to the machine.

Very impressive.

That means your moulds never die.

Never die. Never die.

The 0.6mm-thick recycled plastic sheet

is heated to 100 degrees Celsius,

making it soft and malleable as it moves into something

called a pressure box.

This is where the magic happens.

So, the material goes through the forming station.

This machine is pushing the shape?

Yeah. Fabulous.

Inside the pressure box are rows of aluminium moulds known as dies.

The plastic sheeting is fed above the dies...

..and a plate pushes down with the force of four bar.

At the same time, air is sucked out from below through

holes in the dies, creating a vacuum,

making 14 perfectly formed moulds every time.

The whole process takes just over a second.

As the moulds emerge, they quickly cool and harden.

Then blades heated to 60 degrees punch out 14 individual moulds

at a rate of 400 a minute.

Hey!

Hey. Fabulous.

That's the box for you, Gregg. You can grab some.

Is that it? I think we are all sorted now.

Do you use bath bombs?

Yeah. Every night or once a week?

Once a week.

THEY LAUGH

Thank you, Patryk. That's all you need.

Thank you very much.

Moulds done, I'm ready to make my bath bombs.

I can't wait to get in the bath and try them out.

But any product that touches our skin has to undergo some very

serious testing, as Cherry has been finding out.

We expect a lot from the lotions and potions in our bathroom cabinet.

We trust that all the products we use have been tested

so that they're safe.

Ones like these, with the bunny symbol on,

have had absolutely no animal testing.

But some have.

So, what are the alternatives?

I'm in Cheshire to meet Dr Carol Treasure,

founder of biotechnology company XCellR8, to learn about a pioneering

form of animal-free testing - now available to the cosmetics industry.

What we do is we use human cells and human reconstructed tissue,

so things like artificial skin.

That is absolutely mind-blowing.

So, you make skin,

human skin, in a lab

and that's what you test the products on? Yes.

Well, that's the coolest thing I've ever heard.

Can you show me how it works? Of course.

So, this is where it all starts.

In there, we store hundreds of millions of human skin cells.

Where do you get human skin cells?

They actually come from a tissue bank.

People donate skin when they have cosmetic surgery, for example.

I see. So what does it look like when it comes to you?

It's just a piece of skin in a box, in a special solution,

to keep the skin alive during transport.

And what we do is we then use a substance that

breaks down the skin into the individual cells by breaking

the bonds between those cells.

The cells come from the outer layer of the skin, known as the epidermis,

and are stored in liquid nitrogen at minus 196 degrees Celsius.

When the lab needs cells, they are woken up by warming them

to 37 degrees Celsius - body temperature -

turning their storage solution to liquid.

So, can I see them?

Yes, of course. Let's take a look under the microscope.

Oh, wow. I can see all the tiny, little cells.

That's right. And you can also see it on the screen to the side.

Oh, look! Here we go.

These cells are from the epidermis,

which is the very top layer of the human skin.

Why do you use cells from the epidermis for your research?

Because we want to understand

if a cosmetic ingredient or product is causing damage

to the cells of the epidermis, which would lead to skin irritation.

So, these are human skin cells, just like this? Yes.

Adults have over a trillion skin cells,

and shed millions of them every day.

So, remaining skin cells are constantly dividing to

replace those we lose naturally,

or to help form a healing layer over an injury if our skin is damaged.

Each square centimetre of skin given to the lab provides

more than 250,000 cells, which the XCellR8 team can then grow

using a special pink solution that provides energy and proteins.

We place them into plates like these.

With this lovely cocktail of nutrients,

we then need to expose them to the air,

because our skin is exposed to air.

What happens when they react to the air? What's going on?

These skin cells are essentially trying to cover a wound

and to create a piece of skin.

After 21 days exposed to air,

the cells have multiplied to form

a layer of skin just 0.01 of a millimetre thick.

It's the size of a 5p piece, and transparent.

OK.

Oh, my God, I'm so excited.

And here is the magic product.

So, is this skin ready for testing?

It is indeed.

The skin cells are so thin, they're virtually invisible

to the naked eye.

They float on the surface of the pink liquid nutrients in the pots.

What are we testing today?

Today, we're going to test a chemical that's widely used

in cosmetics and bath products.

We're looking to discover

whether the chemical causes any skin irritation.

The chemical we're testing is commonly used

for bubble baths and soaps.

So, how do you test it?

What Mike's doing now is putting the chemical onto the skin,

and then we're going to incubate it.

The incubator is set at body temperature, 37 degrees Celsius,

to provide optimal conditions for the skin cells to survive.

So, if they die, we'll know it's the fault of the chemical.

So, it's been in the incubator.

What's happening now?

The skin samples are placed into a special dye,

which is converted, by healthy cells, into a purple colour.

So, you can tell if those cells are still alive and thriving,

and happy... Yes. ..because they will convert that dye,

they'll change the colour of the dye? Yes.

That's very clever.

So, we've put the dye on.

And this is what it looks like three hours later.

Right. So, it's purple, which means that the cells are still alive.

Yes. Which means that the chemical is fine.

Yes. So, it's great news.

So, this chemical is not an irritant.

It makes total sense to use human skin to look for

human skin irritation.

The animal tests have been around for more

than 80 years now.

So, they're very, very old technology, in addition to the

ethical concerns that we have about those.

So, these products, which we buy to make ourselves feel good,

not only are we going to know that they're not going to

irritate our skin, but actually we can feel good about them

in every way because we know animals weren't hurt.

Yes, absolutely.

Some of the ingredients at the bath bomb factory are already

tested on human skin cells at the XCellR8 lab.

Just one hour and 50 minutes into production,

both the blue powder and the plastic moulds

I made are arriving at the heart of the factory...

..the 450 square metre assembly area.

Here, 80 people are dedicated to pressing every single one

of the 14 million bath bombs they produce each year by hand.

My blue powder is joined by 100-kilo tubs of yellow

and pink to make the multicoloured Intergalactic bath bomb.

Aiste Samaite is showing me the art of filling.

Aiste? Hello.

You work in a really lovely, smelly, lovely-coloured environment.

You know that? I still love the smell.

I don't think I've ever seen a factory that is this hands-on.

Everybody doing it by hand.

A day, we're making around 30,000 bath bombs.

All by hand? Everything by hand.

I know. We keep telling people. Nobody believes us.

This hand-filling has remained the same

since the bath bomb was first invented over 30 years ago.

Today, they make 61 different varieties!

All right, so let's get started laying down our moulds.

Keep them next to each other.

We can get our powders now.

And if you could put, in a bucket, 6.4 kilo, please.

That's a lot, 6.4.

Yay! Amazing!

So now we need to get our citric as well.

This is the citric acid that creates the fizzy explosion in the bath.

Brilliant!

So, we can pour it on a table.

As soon as we put that citric in, we need to crack on straight away.

So, we've got to work fast because, as soon as this acid goes in here,

it's going to start to harden? Yes.

And you're going to start feeling the difference

in your own hands as well.

The white citric powder is a weak acid.

When combined with the coloured sodium bicarbonate mix,

it reacts to the moisture in the fragrance and colouring,

resulting in a powder that's easier to shape

whilst it's still moist, but will harden up as it dries out.

What a lovely job this is! Isn't this great?

So, we want to mix till we don't see any white bits left.

It reminds me of playing in a sandpit as a child.

So, I think our mix is ready,

so we can sprinkle a little bit in each mould.

Wow! Let me, let me, let me, let me! Let me, let me, let me!

Ha-ha, ha-ha-ha! Ha-ha!

We just need to cover all the bottom,

and we need to do the same with the other side as well.

What a lovely job this is!

Oh, look at this!

It's a fabulous thing.

It really isn't precise at all, is it?

You're doing it all by eye?

Every bath bomb is made by hand,

and the people making it, so every one is different,

with their different personality and size of hands.

Every single bath bomb is individual?

Yes. Just like people who work here.

Everyone is unique. Exactly.

Another benefit of human hands over machines

is that they can retrain to make new products

as and when they're invented.

OK, so we're going to do exactly the same with the pink.

Just grab a pink and sprinkle it out to cover all the edges

around because that's what's going to create

your Intergalactic colours.

What sort of image are we trying to create with this bomb?

A galaxy. Oh, really, like a night sky? Yes.

So, this is our yellow. Yellow!

I really like this.

This is one of the nicest processes

I've ever done in any factory ever,

honestly.

Right, am I sprinkling again?

Yes, we do exactly the same.

Isn't that lovely? Isn't that absolutely lovely?

Last thing to be added is a lump of white bicarb and citric mix.

So, what effect will that give you, then, if a load of white comes

out at the end? It's going to give you,

like, white stars in the night sky.

Mate, this is bath-time poetry. SHE LAUGHS

You're all little bath artists. Yes!

So, now, our bath bombs are ready,

all we need to do to push them together, create a round shape.

So, this is where our blue comes back in,

just need to secure the sides with a lot of powder.

All right. So, once you're ready, we can just put two halves

and put them together.

Push it till the edges are nicely rounded.

Leave me here, I'm happy here.

This is therapeutic.

That, my friend, is a Gregg Wallace bath bomb.

I am so proud of that!

And it looks amazing. Mate, look!

Perfect.

Each bath bomb weighs around 225g.

One down, just another 48 to complete a tray!

What happens to these now, Aiste?

They are ready to go in our hot room to spend the night.

Thank you. Listen, I really enjoyed that. That smelt nice,

and that was actually good fun and therapeutic.

Thank you very much for your help.

30,000 bath bombs at a time enter the hot room...

..where they sit at a temperature between 22 and 28 degrees

Celsius, hardening the powder into the shape of the moulds.

And while they rest, I'm off to test a sample

with none other than the bath bomb inventor

and co-owner of the company, Mo Constantine.

Hello, Mo, nice to meet you. Lovely to meet you.

What are we doing here? This looks like fun.

Are we going to test the bombs?

Yeah. Drop it in?

Gently.

Whoa! Look at that for fizz!

What's happening here, Mo?

Now it's in the water,

you're seeing the effect of

the sodium bicarb and citric acid being saturated by the water,

and that causes everything to burst apart.

And then colours start to separate out into

one big galaxy of colour.

Right now, I'm getting quite a heady, lovely fragrance.

It's lovely, isn't it?

I've got colours but, also, I can see little sparkles.

It's lovely, isn't it?

Tiny, little sparkles, almost like sunlight reflecting in sea water.

Yes. Yeah, yeah. Very nice.

The fizzing action from the release of carbon dioxide diffuses

the gold lustre, colours and essential oils,

a clever and quirky idea for perking up bath-time.

So where did the inspiration come from?

Well, in 1989, I invented the first bath bomb.

I'd got kids by then, and I knew

that they wanted to have some fun in the bath.

The idea of having a fizzing bath I thought was great, so

I was thinking about things that dissolve in the water, that fizz.

You know, you can get medications that fizz.

Did you get the inspiration from maybe, like, a dissolvable

tablet that you drink?

Did you have a hangover, Mo?

That's what I'm asking. Well, sometimes I wonder.

SHE LAUGHS

So, I started to work in my shed,

and you've got your head down and you're literally just pounding away,

making, pressing, sending out the door, everything.

And we actually got to a point

where, by the time we finished in the shed, we'd got two shops.

So, I was making everything in my shed and then shipping it out.

That's a very inspiring story.

Now, you are the highest authority here, Mo.

Has this bomb passed the test?

Yes, I think you've done a pretty good job.

- HE LAUGHS - Thank you, Mo. OK.

For most of us, running a bath is as simple as turning on the taps,

but Ruth's heading back to a time when filling your tub

could be a treacherous process.

MALE VOICE CHOIR SINGS

Throughout Britain's industrial history,

people took on back-breaking, dirty jobs,

but one type of work in particular was notoriously grimy.

Back in the late 19th century,

coalminers were spending 14 hours a day in underground shafts,

accruing a thick layer of grime and dirt on their clothes,

on their skin and in their hair.

At the peak of coal production in 1913, more than a million miners

were employed across the country,

in pits like this in South Wales.

At the end of a long day, hundreds of men would emerge, blinking

in the daylight, desperate for just one thing - a good wash.

To get the dirt on getting clean,

I'm at the Big Pit National Coal Museum in Blaenavon

to meet former miner-turned-historian

Ceri Thompson.

Ooft! Hello, Ceri, nice to meet you!

Bore da, good morning. And you, too.

So, what did miners do, back in the 19th century?

They'd emerge out of a pit...

They'd walk home, basically, don't they, you know?

They're filthy, their clothes are filthy.

They're probably wet as well, cos there's a lot of water,

especially in some of the earlier mines,

so they've got to get home like that.

But like many working people in the early 20th century,

miners' homes didn't have bathrooms

or even running hot water.

Bathing was a much more basic affair.

Ah-ha!

The famous tin bath. Famous tin bath.

And not exactly what people think of when they think of a bath,

but most of the photographs that we see

the late 19th, early 20th century of miners bath-ing,

it tends to be something a bit smaller.

Right, do you want to fill this full of water?

Well, it's not much good empty, is it? No, not much.

THEY LAUGH

Filling the tin baths with hot water was a job that fell

to the miners' wives.

With no bathroom, the bath was set up in front of the fire.

And after fetching cold water, often from a well, or even rivers,

it had to be heated on the stove,

ready for their husband's return from the pit.

Hang on. That's hot. Oh, my pan's hot, too.

Fetching the water, boiling the water, keeping it on the go

until your man comes in, it's a lot of work!

There's a whole process in doing this, and it's a heavy process.

You know, it's a dangerous process.

Were there accidents?

The doctor in Aberdare in the 1930s wrote a report on the area

and said it was more likely that a woman would be injured in the

kitchen than her husband would be on the coalface.

Right. A lot of children were scalded in the house. Yeah.

Even in my mother's time,

she remembers children being scalded because of hot water.

♪ Down yonder green valley where streamlets meander

♪ When twilight is fading... ♪

This dangerous daily bathing routine

continued well into the 20th century.

It wasn't until after the First World War

that the Government set up a Royal Commission to investigate

living and working conditions in the coalfields.

As a result, the Miners' Welfare Fund

was set up in 1921,

and they eventually put a levy on coal to fund the provision of

washing facilities at the mines,

known as pithead baths.

The baths here, at Blaenavon, were built in 1939.

The baths are through here. OK.

This is a long way from a tin bath in front of a fire.

Now, you said "baths", but these look like showers to me.

Yeah, they are showers, they were always known as "the baths".

I even call showers "baths" in the house.

Do you really? Yeah.

It must have seemed like such a luxury to have plentiful hot water,

heated by coal-fired boilers,

instantly available after a hard shift down the pit.

So, how many men are bath-ing in here all at once, then?

Well, there's room for just under

100 people, one way or the other, you know? Right, OK.

There was times when the baths was busy that

two people would be bath-ing in the same shower,

but they had to be good mates to do that.

So, this must've made a huge difference, as a working person,

to be able to have this element of cleanliness.

Enormously important. Enormously important

for the miner's wife as well, obviously,

because she's the one that's got to deal with all this stuff now.

You know, these gallons of dirty water,

you're washing it all away, aren't you?

By the time the mines were nationalised in 1947, there

were 366 pithead baths across Britain

giving a good wash to 400,000 miners...

..and ending the demanding and dangerous practice

of wives preparing the tin bath in front of the fire.

The closure of the last deep coal mine in Britain in 2015

saw the final pithead baths shut.

Life in mining communities was always tough

but, for almost a century,

these palaces of cleanliness brought better health and dignity

to the men who worked so hard to power the nation,

and to the wives who supported them back home.

Thankfully, things have moved on from those old tin baths.

These days, we have the luxury of adding colour, fizz

and fragrance to our bath-time, just for fun.

Here, they make bath bombs with names

like Twilight and Unicorn Poop.

I've mixed, filled and tested my Intergalactic bath bombs,

and now a batch of 3,000 is heading over to Packing...

..ready for the expert attention of Charlie Cutler.

Charlie? Oh, hello! What do you reckon to them?

They look very good. Would you like to learn how to pack them?

Yeah, I really would.

The first thing we need to do is remove the mould. I know why you

take the moulds off, you recycle them, don't you? Absolutely, yep.

Oh, you've taken all the tops off first? Yep. Wow!

Would you like to pop them in the box? Yeah, yeah, yeah.

So how many go in a box? So, these ones, it's 50 in a box.

Two rows of 25. Why do you pack them naked?

To reduce our waste footprint,

we're selling as much of our products naked.

Do you actually call it "naked", do you? Absolutely!

To be fair, they had see-through costumes on anyway.

THEY CHUCKLE

For a company that makes a ton

of these bombs every day,

nearly everything's hands-on.

Well, we do like to pride ourselves on being handmade.

The balls are tightly packed so they don't get damaged in transit.

If you want to put two more pieces of paper on the top.

And protected by recycled paper,

they have a shelf life of six months.

And then you can seal the box up.

So, we've got one more last thing to do.

We like to put our faces on things, so we had these made for you.

Oh, look at them! Ha-ha!

Look at that, look.

That is fabulous! It's spot-on.

Charlie, you're a star.

Where's this going now?

All ready to go down to Dispatch, down that way.

Thank you, Charlie. Thank you very much indeed. Thank you very much,

it's been a pleasure.

My personalised boxes of bath bombs are finally heading to Dispatch.

It's a huge building, the size of two football pitches.

Even the dispatch smells OK.

This is now my favourite factory, it's official.

I'm meeting up with Chris again.

Hey, Chris. Ah, Gregg.

Good to see you, man!

Good to see you. I have got some top bath bombs here.

Where do you want them? Wonderful.

If you can get it on here for us?

Is that now a complete pallet?

That is a complete pallet ready to send out to our Liverpool store.

Well done, old son.

Come on, let me give you a hand.

Cheers, Gregg.

My pallet of Intergalactic bath bombs is ready for shipping.

The bath bombs I made,

how many of those do you send out every day?

We send out 3,000 of those.

Wow. Seriously? Yep.

Is that one of your...? Is that the bestseller?

That's one of our bestsellers, yes. 3,000 a day? Yeah.

So what's that - five days a week, 15,000 a week? Yeah.

Over our peak season, we send out over 120,000 a week.

And when's your peak season?

Our peak season goes from the end of November through December,

ready for Christmas.

Wow, that's impressive.

There's one box that has got some special stickers on it.

Much sought-after. Limited edition. Collector's item.

HE LAUGHS

Somebody, somewhere in the country,

is going to be having a bath with Gregg Wallace.

That's a nice-smelling truck.

Is it ready to go? It's ready to go. Ready? Yeah. Bombs away!

After 28 hours and ten minutes,

my bath bombs are heading 266 miles to Liverpool...

..and they're transported to more

than 100 stores across the UK,

enlivening the bath time of people

as far as Belfast and Inverness.

It seems we've all gone crazy for a fizzy bath.

I have thoroughly enjoyed my time here.

But what's really surprised me is just how hands-on it is,

not a single bath bomb made by machine.

I've never been to a factory that is so fragrant, so colourful,

and so much fun.

The factory has come a long way from its first early assembly lines.

But how did we get from there to here?

Explore the history, and future, of the factory

on an interactive timeline.

Go to...

..and follow the links to The Open University.