I make neem oil soap for my Mom each year around the holidays.

Had some leftover starting materials this year, so I thought I would make some soap for myself and try to infuse it with rosin.

I’m not really sure if it will work out. Not really sure if rosin soap will actually make a person cleaner, or not.

As a percentage of weight, the soap made by this recipe has 0.6% rosin, and likely half that amount in cannabinoid content. So I hope to find out, but I may not notice a difference. 

I’ll show the recipe I used, show some photos from the process, and give some thoughts I have on the procedure.

The soap is curing currently. After it’s done, I’ll come back with pictures and further thoughts.

Ingredients
  • 210g of water
  • 78.5g of Sodium Hydroxide (NaOH)
  • 254g of Shea Butter
  • 200g of Coconut Oil
  • 100g of Olive Oil
  • 17g of fragrance
  • ~5g rosin
Tools
  • two pots
  • glass bowls (3)
  • wooden spoon
  • metal spoon (2)
  • scale
  • thermometer
  • stove
  • rubber gloves
  • safety glasses
  • mold
Procedure

I do a casual step by step here, I skip over lots of details about making soap.

There are far better places to learn how to make soap. There’s also some good things to know about working with lye, or sodium hydroxide, which you should learn elsewhere, or by watching Fight Club.

Weigh and melt oils

I weigh the oils while a pot is on the stove under low heat.

Once I make weight for each oil component, I toss it in the pot and reuse the glass bowl used for weighing.

I also scoop an amount of rosin into a spoon, and place that in the hot oil. The rosin eventually drops off the spoon to dissolve into the oil.

prepare Sodium Hydroxide Solution

Once all the oil is weighed, I check the temperature of the oils, and take it off the heat.

I weigh the water and add to the second pot. Then I put on gloves and glasses, and weigh the sodium hydroxide, keeping the powder in a clean glass bowl.

Then I slowly add the sodium hydroxide to the water, while stirring.

Mix Sodium hydroxide solution into the Oil

Once the NaOH has been mixed with the water, I check the temperature of the water, which has increased to about 130-140f. Ideally, the oil has cooled to the same temperature, 130-140f.

I give a bit more time to cool, before slowly mixing the sodium hydroxide solution into the oil mixture, while stirring the oil.

Then I stir for 10-30 minutes, until drippings from the spoon float on the surface of the oil/water mixture, this is called trace.

add Fragrance

At this point I add the fragrance, while stirring.

I went with citrus, mint and vanilla.

pour into Mold

After some more stirring, I pour the mixture into a mold.

I place in a warmer room for curing.

Thoughts and Hypothesis
Saponification

In this reaction, a hydroxide ion attacks a dipole positive carbon in an ester group, which is similar to a carboxylic acid group present in cannabinoids. So here’s one thought, would a hydroxide ion react with a carboxylic acid group in the THCA present in the rosin? Or with THC (decarboxylated)?

My hypothesis is no. Not all of the THC in the rosin will be acidic form (I assume some has decarboxylated under pressure and over time). When I heated it above 140f in oil, it should have decarboxylated further, and there may be more attractive targets for a hydroxide ion on the THC molecule or elsewhere in the solution.

Either way, the recipe used is superfatted, meaning I used more oils than hydroxide ions available to react, so there will be some mix of components that have, and have not reacted with the hydroxide, but all of the hydroxide will have reacted. This is to ensure the pH of the soap is neutral, not basic.

Order of Operations

I added the rosin before I added the sodium hydroxide. As per above, the THC may have reacted with the hydroxide ions.

Alternatively, I could have added the rosin with the fragrance, after the sodium hydroxide had been allowed to react with the oils. Should this soap turn out poorly, I may try this next time.

If it does work out, It may have been easier to infuse coconut or MCT oil with the rosin, or other cannabis before making the soap. I only mention it because coconut/MCT can also be used for edibles and other topicals, some may find it convenient to keep a larger container around.

Content Estimation

I used 5 grams of rosin, about (it didn’t register on the scale I used). Assuming it’s 50% pure, that’s 2500mg of some cannabinoids. I’d estimate we come out with 750-850 grams of soap, or just over 300mg of any cannabinoid per 100g bar of soap. Of course this is just an estimation, with degrees or error from decarboxylating the rosin in oil, and any degradation that may have happened by the hydroxide that I’m not yet aware of.

Wait for curing

I’ll update this in a few days when the soap is done curing. I’ll need to cut it and take some photos of it.

Here is how Mom’s neem oil soap turned out.

Cut Soap

Here’s a few pictures of the rosin soap after about 96 hours in the mold.

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