Shower steamers: the chemistry behind ?

[CecileBC]

Hi !

I would be interested in understanding the chemistry behind shower steamers:
is it the bonding between citric acid and baking soda, packed together firmly with a binding agent such as rubbing alcohol or witch hazel, that creates a new chemical structure that is rock hard ?
Does it mean that the 2:1 ratio between baking soda and citric acid has to be respected if one wants to make the structure rock hard ?

I have tried numerous recipes, and I seem to find that the 2:1 ratio gives the best results in terms of hardness.
However, I would like to decrease the fizz effect, so I have tried less citric acid and have added either cream of tartar or a clay to my steamers.
It turned out that none was ever as hard as the ones made with a 2:1 baking soda/citric acid ratio - and some of them totally crumbly!

Thus my question to try and understand the "chemistry" that happens in the process.

Thanks !

 

[Mobjack Bay]

I have the same exact questions and will be following along. I think there are some answers in the videos by Creative Bath Lab but I need to watch them again.

My best steamers to date included some rose clay. It also seems that once a batch has failed/won’t hold together, there’s no saving it. The stuff will still fizz, so I’m perplexed.

 

[AliOop]

I use kaolin clay in mine, and they do get quite hard and work pretty well. I imagine that cream of tartar or cornstarch would work well, too. My recipe is from The Untidy Artist aka Emily Leffler (sp?) on YT.

Like bath bombs, I use the leftover loose stuff as a toilet cleaner powder.

 

[CecileBC]

I have the same exact questions and will be following along. I think there are some answers in the videos by Creative Bath Lab but I need to watch them again.

My best steamers to date included some rose clay. It also seems that once a batch has failed/won’t hold together, there’s no saving it. The stuff will still fizz, so I’m perplexed.

Exactly, I also wonder why it sometimes fails miserably... It seems to have something to do with the binder, as I find I get different results when using rubbing alcohol only, or a mix of rubbing alcohol mixed with witch hazel... best results, for me, with rubbing alcohol only, or a small amount of witch hazel. I will watch Creative bath lab again - I know she has a good video on strong bath bombs.

 

[CecileBC]

I use kaolin clay in mine, and they do get quite hard and work pretty well. I imagine that cream of tartar or cornstarch would work well, too. My recipe is from The Untidy Artist aka Emily Leffler (sp?) on YT.

Like bath bombs, I use the leftover loose stuff as a toilet cleaner powder.

Hi ! I have tried Emily's recipe, and it ended ok but not strong enough for safe handling and transportation...
Such a great idea to use the leftovers that way ! My family is getting a little sick of leftovers in the shower

 

[Mobjack Bay]

I’ve only used 91% rubbing alcohol so far, with some excellent batches and some that won’t hold together.

I found this thread that includes suggestions for using cream of tartar or clay, and tight packing, for producing harder bath bombs.

https://www.soapmakingforum.com/threads/how-to-make-bath-bombs-more-hard.77769/

 

[CecileBC]

I’ve only used 91% rubbing alcohol so far, with some excellent batches and some that won’t hold together.

I found this thread that includes suggestions for using cream of tartar or clay, and tight packing, for producing harder bath bombs.

https://www.soapmakingforum.com/threads/how-to-make-bath-bombs-more-hard.77769/

Thank you, interesting information there. I wonder what cream of tartar does that is different from Kaolin clay. Both are quite expensive...

 

[DeeAnna]

Cream of tarter is potassium bitartrate, an acidic salt, meaning when it's dissolved in water, it creates an acidic solution (pH below 7). It is slightly soluble in water.

Clay is insoluble in water and thus has no pH to speak of, unless it contains adsorbed chemicals that can dissolve in water to alter the pH.

If you're specifically using kaolin clay, it probably functions as an inert powder -- I'd guess something similar to cornstarch. If you're using another clay, this might not be the case, since various clays have varying properties.

I am not a bath bomb maker, so I have no idea why one might work differently than the other in a bath bomb.

(For comparison, soap is an alkaline salt and it makes an alkaline/basic solution (pH above 7) when dissolved in water.)

 

[AliOop]

@Mobjack Bay and @CecileBC you both make good points. I have only used 91% RA, as recommended in Emily's recipe. If someone were to use the more commonly-available 70%, their steamers would definitely be softer due to the higher water content.

I also use a manual bath bomb press like this one. This gives me so much more leeway with the moisture level of the mix, which means more working time as the mixtures starts out wetter at the start of a session, and ends up drier due to evaporation along with way. My steamers end up rock-hard with no crumbles. I can shrink-wrap them within an hour after unmolding.

Before that, I used mooncake presses. I loved the designs, but it took so much time and physical energy to pack the materials firmly enough to get a hard steamer. There were lots of "fails" that had to be thrown back into the mixing bowl and then repacked - which was quite time-consuming and frustrating.

My grandson is planning to make a 3D printed mold for me that combines the pretty designs of the mooncake press with the better packing ability that comes from using a manual press. If that works, he's hoping to start selling them on FB Marketplace and Etsy. At 12, he's quite the entrepreneur!

 

[CecileBC]

Cream of tarter is potassium bitartrate, an acidic salt, meaning when it's dissolved in water, it creates an acidic solution (pH below 7). It is slightly soluble in water.

Clay is insoluble in water and thus has no pH to speak of, unless it contains adsorbed chemicals that can dissolve in water to alter the pH.

If you're specifically using kaolin clay, it probably functions as an inert powder -- I'd guess something similar to cornstarch. If you're using another clay, this might not be the case, since various clays have varying properties.

I am not a bath bomb maker, so I have no idea why one might work differently than the other in a bath bomb.

(For comparison, soap is an alkaline salt and it makes an alkaline/basic solution (pH above 7) when dissolved in water.)

Thank you, I was hoping for a feedback from you DeAnna
Yes I guess clay works as a "cement", filling the holes left in the mixture.
As for cream of tartar, I understand it could almost work as citric acid, being an acidic salt, but it seems that people put it in to make the steamers harder... and I don't understand why?

 

[CecileBC]

@Mobjack Bay and @CecileBC you both make good points. I have only used 91% RA, as recommended in Emily's recipe. If someone were to use the more commonly-available 70%, their steamers would definitely be softer due to the higher water content.

I also use a manual bath bomb press like this one. This gives me so much more leeway with the moisture level of the mix, which means more working time as the mixtures starts out wetter at the start of a session, and ends up drier due to evaporation along with way. My steamers end up rock-hard with no crumbles. I can shrink-wrap them within an hour after unmolding.

Before that, I used mooncake presses. I loved the designs, but it took so much time and physical energy to pack the materials firmly enough to get a hard steamer. There were lots of "fails" that had to be thrown back into the mixing bowl and then repacked - which was quite time-consuming and frustrating.

My grandson is planning to make a 3D printed mold for me that combines the pretty designs of the mooncake press with the better packing ability that comes from using a manual press. If that works, he's hoping to start selling them on FB Marketplace and Etsy. At 12, he's quite the entrepreneur!

Do you have a picture of the manual press ? I cannot see it as it says it is not available in our part of the world...

 

[AliOop]

Sure, here you go:

 

[AliOop]

As for cream of tartar, I understand it could almost work as citric acid, being an acidic salt, but it seems that people put it in to make the steamers harder... and I don't understand why?

Because it does work to make them harder.

But perhaps you are wondering, why use expensive cream of tartar when you can use cheaper kaolin clay, or even cheaper cornstarch? The answer is, some people get their best results with one of these ingredients rather than the others.

Bath bombs and shower steamers are finicky things since they can be very dependent on humidity, minute changes to water content, and the like. So when someone who has had a lot of fails finally lands on a recipe that works for them, they typically stick with it - even if one of the ingredients (like cream of tartar) is a bit pricier than others that could be used.

 

[CecileBC]

Sure, here you go:

View attachment 81422

Thank you !