GIY Soft Scrub with Dr. Bronner’s

Don’t tell the others, but this recipe’s my favorite of all my Green-It-Yourself (GIY) concoctions made with Dr. Bronner’s products. Now mind you, this shouldn’t be your very first GIY—that place belongs to the All-Purpose Cleaning Spray, which if you haven’t yet made, you need to go do right now. But this one is the most fun. It is the mesmerizing magic of chemistry right before your eyes. 

What is GIY Soft Scrub good for?

The beauty of the GIY Soft Scrub is that it clings to vertical surfaces, so it is a great aid to clearing away soap scum off shower walls, rings around the tub, mold in grout, stubborn water spots on glass. This is also great for toilet bowls and shining up kitchen sinks. You’ll probably find a bunch of other uses, too.  

And it’s really fun to make. You get to see a simple and safe acid/base reaction (respect pH!) and you get to run your hands through some soft and sudsy foam. Therapeutic indeed!

The chemistry of GIY Soft Scrub

I first learned the basis of this recipe from Karen Logan’s pivotal book Clean House, Clean Planet. However, it took me some thought to figure out why this recipe works. You may have read me say elsewhere not to combine Dr. Bronner’s Castile Soap (or any true soap) and vinegar, and that even Dr. Bronner’s Sal Suds and vinegar isn’t a helpful combo. So why does it work here?  

There’s a bit of drama going on. A love triangle, if you will. There are two ingredients in this mixture that vinegar likes to react with: baking soda and Castile Soap (or Sal Suds, though to a lesser extent). Vinegar and baking soda produces that lovely fizzy reaction that fuels many a child’s volcano experiment. Vinegar and Castile Soap, on the other hand, produces a useless gunk.  

Happily, vinegar is more readily reactive with baking soda than with Castile Soap or Sal Suds, so the baking soda basically runs interference, engaging all the vinegar in a gassy little dance party. There’s no vinegar left to mess up the soap or Suds.  

But that’s not the only question you might be asking. I also say elsewhere (like in my book) that the reaction between vinegar and baking soda, fun as it is, is not useful for cleaning. It is all fizz, no function. This is still true.  

Baking soda and vinegar is not useful for cleaning, but it is useful for foaming. When baking soda and vinegar react, they create gaseous carbon dioxide. That’s what’s being released in the fizz. This gas then gets trapped in the Castile Soap or Sal Suds, which is just sitting there waiting for some action after the vinegar ditched it in lieu of the baking soda. The carbon dioxide trapped in the cleaner makes thousands of tiny bubbles, resulting in all that lovely foamy texture that clings to vertical surfaces.  

The reaction between the vinegar and baking soda creates the structure of the GIY Soft Scrub. 

How does the GIY Soft Scrub work?

Now that you have that beautiful foam that clings to vertical surfaces, let’s look at what is actually doing the cleaning. Two things: the surfactant (Castile soap or Sal Suds) and an abrasive (baking soda).  

Though the Soap or Suds has bubbled up with the carbon dioxide, it is still available to do its surfactant action. A surfactant is the general chemistry term for a substance that reduces the surface tension of water. They also clean by encasing every bit of grime in a little sphere of molecules called a micelle, ready to be whisked away in the rinse water.  

The baking soda, on the other hand, cleans by brute force. Mechanical action literally pushes grime off of surfaces, loosening it so that the rinse water can take it away. The amount of baking soda in this recipe means that while some will be used up in the reaction with the vinegar, there is plenty left to do this scouring. 

Which to use: Castile Soap or Sal Suds

You’ll notice the recipe can be made with either Dr. Bronner’s Castile Soap or Sal Suds Biodegradable Cleaner. In this case, they are interchangeable. You are welcome to use whichever you have or whichever you prefer. Since the Sal Suds is more concentrated, you need to use less. You may find that Sal Suds takes more rinsing, so the Castile may take less time. But they both work equally well in this recipe.  

For further info on when to use which of these versatile products, check out my article Which to Use.

Shelf life of the GIY Soft Scrub

One difference in making your own cleaners versus buying them is shelf life. You’re not adding preservatives or stability enhancers. If you leave this mixture in your cabinet for weeks, it may separate, with the baking soda settling on the bottom. If this happens, you can do a couple things. First, shake the bottle vigorously and see if that remixes it. Second, add some vinegar to the bottle and then swirl the bottle vigorously with the cap off. Keeping the cap off when adding vinegar is essential because with the production of carbon dioxide during the reaction, a closed bottle will explode.

How to make GIY Soft Scrub with Dr. Bronner’s 

Ingredients  

• 1 c. (240 mL)  Dr. Bronner’s Castile Soap OR ¼ c. (60 mL) Dr. Bronner’s Sal Suds 
  3⅓ c. (800 g) baking soda 
  1 c. (240 mL) water 
  ¼ c. (60 mL) distilled white vinegar 

In a big bowl, combine the baking soda with the Castile Soap OR the Sal Suds. Mix it with a fork until well blended and no lumps remain. Add in the water and mix thoroughly again. Add in the vinegar and keep stirring until no lumps remain. Add additional water if needed until mixture is a pourable consistency. Pour the solution into an empty quart bottle, using a funnel.

How to use GIY Soft Scrub

To use this, squirt it over the surface and wipe with a damp microfiber cloth. Rinse with a wet cloth. 

And best of all, since these ingredients are simple and safe, kids can use them, too! Hand this bottle over to them and let them scrub away! 

Further Reading

• GIY All-Purpose Cleaning Spray 

• Green Cleaning Your Bathroom 

• Castile Dilution Cheat Sheet 

• Sal Suds Dilution Cheat Sheet 

Sal Suds cleaner shows >60% biodegradation after 28 days per ISO 14593.