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Bath Bombs 101: It’s all about that base

…Aka everything you’d like to know about the geeky chemistry on what is going on when you put them into water.

Okay, so let’s start with the key ingredients to create some magic in the tub (that I use as my basic recipe):

  • Sodium bicarbonate more commonly known as baking soda
  • Citric acid
  • Cream of tartar (known by chemists as potassium bitartrate)
  • Oils
  • Water


Sodium bicarbonate is normally ingredient you’d have known from baking that is responsible for raising the dough (my favourite type of dough these days is crumpet! What is yours?) with white powder appearance. In bath bombs however, it is taking a crucial role of weak alkaline with pH of approximately 8 (neutral pH is 7) and taking part of in nautralisation reaction together with citric acid. The most popular way to produce baking soda these days is to use the Solvay process, but also could be made from trona ore, which is firstly mined. The source of trona ore is previously evaporated Green River in Wyoming, and apparently it’s enough to meet world’s bicarb soda demands for thousands of years!


And again, citric acid is an ingredient you’d probably find in the kitchen – either in citrus fruits, such as lemon and lime (8% of weight of a citrus is citric acid) or on Pancake Day when you are eating your lemon and sugar crepes. Citric acid is weak acid with pH of around 2.2 and it has white, crystalline structure. More commonly now though it is made in the lab – and rightly so as there would not be enough citric acid in the world to meet the demand! I would like to speak on sustainability of the bath bomb ingredients in future posts, as I think it is very interesting matter that not many people consider. But back to bath bombs…


Without water, baking soda and citric acid would not react – they would happily be sitting mixed with each other as if nothing happened, but once water is introduced to the system, that’s when the magic happens – the neutralisation reaction! It’s called like that because weak acid meets weak base and they neutralise each other. In this case, carbon dioxide gas is produced and hence the fizz we experience when we throw a bath bomb to water. The fizz has other purpose – it distributes other ingredients in the water efficiently and helps the fragrance from essential oils fill the bathroom and make us feel all happy and relaxed. Cool, huh? Below you can see a reaction with scary molecular models that I tried my best to simplify (I do like chemistry).


Last ingredient of my basic recipe, cream of tartar, or potassium tartrate (no one uses that name, so let’s stick with cream of tartar). It has one, simple but important role of binding the bath bomb and making it hard – very important if your bomb could fall, as you don’t want it to break into million pieces (this moment when you’re made some fro your mum and you dropped it on pavement as you were getting into the car… Sad moment of my life). Cream of tartar is a by-product from wine production as “wine crystals”. It is then filtrated and crushed into powder. Also – again baking ingredient – could be used in meringue to make it fluffier!


Other ingredients are water and oil – they are binding agents. I will elaborate much more on oil in other post, but if it comes to water it needs to be used sparingly due to the fizz activating properties – it activates the neutralisation reaction, so we don’t want to start anything prematurely… (wink wink). Your best bet is to spray a bit of water and mix fast, so the mixture won’t start to fizz.

Another very common ingredient in bath bombs is cornstarch. It is used as a “filler” in bath bombs and it also slows down the reaction between baking soda and citric acid. I decided not to include it as I want to offer quality bath bombs packed with nourishing ingredients for body and soul rather than fillers. Yes, fizzes out quicker, but if that’s the sacrifice I have to make I am happy with it!

Other additional ingredients are milk powders, clay and essential oils – more on that in next blog posts!

I hope you found it interesting and not too boring!

Michalina x

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Hello guys!

Firstly, warm welcome to my very first blog post in my life! My name is Michalina and I am the founder of Polka Lab Cosmetics.

I am also a chemistry geek, who is obsessed with natural/organic/sustainable cosmetics. I have been following the industry for around 8 years and I have been dipping in and out of making my own cosmetics. It was my dream to work in the cosmetic industry, and deep, deep down I always knew I wanted to create my own cosmetics brand. I thought it’s either now or never, so here I am! With all these years in being stuck in the beauty world I have learnt a thing or two and I always wanted to share my knowledge. By no means am I an expert as I am still learning, but I would love to promote the benefits of natural and organic beauty, teach you how to make your own DIY cosmetics and give you insights into my brand! There are few other things that you may want to know about me:

  • I am Polish (if you didn’t get it from my weird sounding name) and I came to UK almost 9 years ago. That’s where the name “Polka Lab” came from – polka means “Polish girl” in Polish. Lab is pretty much explanatory!
  • As English is not my first language I tend to make some grammar mistakes. Especially when I’m nervous. Latest one was “bowls of waters”…
  • I chat a lot. I am an extrovert, who likes to be around people and talk through problems and use others as a sounding board. Believe me, by now my other half definitely knows how to make a bath bomb…
  • I am very easily excitable! If you’re following me on Instagram, you will notice I use phrase “I am so excited!” pretty much in every other sentence.
  • I like to be busy – time not doing anything is “lost” for me and having a tight schedule makes me feel productive!

I could keep going, but let’s stop on the last point. That’s where a big WHY for Polka Lab was born.


As I mentioned above, I love to have my days filled to the brim and constantly be busy. I often noticed I cared much more about other people, their feelings and needs rather than my own. I never thought that was wrong apart from the times where I felt anxious that I have done something wrong and upset anyone and that’s when the overthinking EVERYTHING came into play. Last year I met a coach, Sarah, who has held my hand when I was making first steps into the business world. She has shown me importance of falling in love with myself first, taking care of myself, taking time for myself, filling up my batteries and gratitude for what is in my life (I had a pretty awesome life, however there was always something wrong with it. It’s not anymore!). I started to feel so strongly about it, that I decided to make it my brand’s purpose. In an ideal world, I would like everybody to put themselves first, as you can’t give to others if you are unhappy. Think about it like a flat battery won’t make your phone work, or putting the oxygen mask in a plane emergency on yourself first before you help others. It’s so important to make sure you find time to do things you like to do and what sparks joy (a bit too much of Marie Kondo here, but she has a point). By using my products I would like you to make sure that you take time for yourself every day – would it be an hour for a bath using bath bombs (more on that in a second…) or 10 minutes to take your make-up off after long day and massage in that miraculous facial oil that will make your feel like a new woman.

That’s where idea of my first product came from – a Bath Bomb! What does scream self-love more than a good, old bath?! I love to take a bath, but I don’t do that often enough. In fact, my mum is a pioneer in taking baths – she has one everyday! Anyway… I wanted my bath bombs to make you feel amazing, so I have used highest quality organic Essential oils – and in every bath bomb you can find at least one oil that has aphrodisiac properties. This is not only for obvious reasons, but also to make you feel confident as hell and release all those negative emotions accumulated throughout the day. In my next posts I will elaborate on all of the ingredients to you know exactly what is in them!

Bath bombs will be available for sale after 27th of March, BUT if you live around Liverpool, you can join me in celebrating this massive milestone by buying tickets for my launch party HERE!


There were workshops! In summer last year I started to do my workshops around DIY bath bombs and bath salts. I was also touching on the importance of finding time for yourself and self-love. The most important thing for me was to plant a seed in attendees – by creating small changes in their life in order to find more time for themselves they could create habits that would improve their lives… And they had. I got the most amazing feedback – one girl decided to leave her job in KFC and concentrate solely on her goal of becoming an actress, other decided to pursue taking classes to learn new language. Honestly, even thinking about it makes my heart flutter! I absolutely loved the workshops and they will be coming back this year.

Other big part of my workshop is to make sure you understand what you’re putting on your skin and choosing the best ingredients. I was spending significant part of the workshop on explaining the benefits each of organic oils and organic essential oils we were using so girls could personalise their bath bombs to themselves and their needs!


As I mentioned above, I feel it’s really important to understand what you are using on your skin. That’s where the idea of “slow cosmetics” came from. As in slow food, you know why you are using particular ingredients in your dish, and why you’re eating it, I wanted to bring the same idea to my brand. I want people to understand the role and benefits of each ingredients, and make sure they’re using the ones that their skin needs. I will be trying my best to explain that in following blog posts here, so you are well informed. As I am a scientist myself, I like to base it on actual facts and a lot of research, so expect that here too! I understand that scientific publications are super hard to get your head around (I tend to read them at least two times before things click), so I am planning to explain the research in more easy-to-digest way. I would like to use this blog to share as much knowledge with you as I can, as sometimes it’s hard using social media. I hope you will get stuck into it as much as I had 🙂


I did say I like talking, didn’t I?! I didn’t realise how long this will get, but I guess I will finish for now. Make sure you follow my social media: Instagram and Facebook. If you fancy joining my in celebrating my Bath Bomb Launch, make sure you get your ticket here, and here you can find the event page on Facebook.

Till the next one!

Michalina x