After making foaming hand soap with Dr Bronner Castile Soap, I decided to try making dish soap with it.  According to this Dilutions Cheat Sheet, I know the soap diluted with just water would be too thin for our preferences.  KT especially likes his dish soap thick like the store-bought soaps.  Again, there are a ton of recipes out there to make thicker dish soaps with castile soap but they are all more complicated or time-consuming than I liked.

After some research, I found that salt can be used to thicken soap (like this here, here, and here).  I’ve also considered using glycerin but I decided to try with salt first.  It did not come out as I have hoped but it (sort of) worked.

Here’s what I did:

First, I made the dish soap according to the Dilutions Cheat Sheet. Next, I added about a teaspoon of salt.  I mixed it well.  Let it sit overnight.  But it didn’t get a thicker.  I added more salt but it didn’t make a difference.  Then I remembered reading about the salt curve.  Too little salt will not make the soap thicker, and too much salt will make the soap thinner.  Since I didn’t know how much salt is needed to thicken this particular soap, I decided to be a little bit more systematic about this process.

In my second approach, I made a much smaller batch: 1 oz of the Castile Soap diluted with 10 oz of water.  Then I mixed in 1/8 of a teaspoon of salt.  It didn’t get any thicker. I added another 1/8 of a teaspoon of salt.  No difference.  I started having this sneaking suspicion that this particular soap can’t be thicken with salt.

So in my third approach, I decided to just add salt directly to the castile soap (before diluting) to see if this particular soap can be thicken with salt in the first place..  I took one ounce of castile soap, and added 1/8 tsp salt.

It thickens!  Hip hip hooray!

I added another 1/8 tsp of salt, it thickens even more.  It was almost paste-like.  This is a good sign.

I decided to add the batch from my second approach to this third batch.  I only mixed in enough to make my paste like mixture thin again.  Then I added another 1/8 tsp of salt to thicken it.

I repeated the process of adding more of the diluted soap from the second batch to my current mixture until its thin again and then adding salt to thicken it.  When I have finally combined the entire second batch with my current batch, I had a mixture of 2 ounces of castile soap, 10 ounces of water, and three and a quarter teaspoon of salt.

After letting the soap sit overnight, I discovered that the salt/soap separated from the water.  I have to stir it to mix it up again.  I tried using it and it suds up really well.  The end result is a very clumpy dish soap that separates from the excess water.  Surprisingly, the first batch didn’t separate like this 2nd/3rd batch mixture.  I’m going to use up these batches of soap first before I try again with glycerin.  Hopefully I’ll have better luck.