One of the first questions most people considering the purchase of handmade soap as is how long a typical bar will last. After all it costs more than the factory-made bars you can buy at any grocery or big-box store.
One 4-ounce bar of handmade soap typically lasts an adult user 25 to 30 showers once in use. Prior to use, handmade soap has an active shelf-life of one to two years depending on the amount and type of extra (unsaponified) oils contained in the bar.
How to Make Handmade Soap Last Longer
After finding out how long a bar of soap lasts, the next question is always “how can it last longer?” There are several ways to make bar soap last longer – by both the user and maker, as follow…
As a User of Soap
When using soap there are a couple things you can do to get the most out of a bar. They are easy and to do and will save typically make your soap last up to fifty percent longer.
Keep the Soap Bar Dry
If you can keep the bar dry when not in use it will last far longer. This is most easily accomplished by using a draining soap dish or simply using a dish that keeps the bar free from sitting in water.
I personally use soap savers. There are different types ranging from a rack of bars/ridges to elevate the soap and allow it to fully drain – to cloth and plastic mesh bags to hang the bar.
Two other popular types are a pad of plastic oils to rest it on and dished with a bed of raised vertical posts to hold the bar aloft and maximize airflow.
Use a Washcloth or Loofa
For soaps that do not need direct contact to your skin, use something like a cloth or loofa to apply it.
Soaps with salts and exfoliants work best when applying the bar directly to the skin because the bar is the intended delivery system. For typical soap however, it works best to use a washcloth or loofa to maximize the lather while using a minimal amount of soap.
The same principle applies when using liquid dish soap on a sponge verses just squirting it onto the plates. If you have ever had that “Aha!” moment when washing dishes you know exactly what I mean.
As a Maker of Soap
The longer lasting the bar the user starts with, the longer it will last in the shower. That’s common sense of course, but important to consider. Even if you do just one or two of the following things, your soap can last days or even weeks longer for your customers.
Fully Cure the Soap
Curing the bar to be as firm as possible is the best way to make it last longer in the shower. Most people experienced with homemade soaps will judge a bar by its hardness along with other qualities. The closer you can get your soap to “rock hard” the better.
Although curing has several steps and two potential meanings, we will look at it as the removal of any excess liquid in the soap. Any additional liquid in the soap makes the bar softer. Even if it feels very firm on the outside, there may be water contained within the bar.
To remove that added moisture, try any or all these methods:
- Allow the soap to cure for an extra two to four weeks in a dry environment with ample air movement.
- Add a small dehumidifier or silica water trap (moisture remover) to the area where the soap is curing.
- Place one or two low-power fans in the area to help circulate the air. Oscillating fans increase airflow to a greater coverage area, which is also helpful.
Here is moisture trap that should last for several large batches of soap. It’s just $1 at places like Dollar Tree and Walmart.
Use Hard Oils in Your Soap Recipe
As a rule, the harder the oils used, the harder the bar will be. As mentioned above, harder bars last longer.
A hard oil or fat is anything that is solid at room temperature (about 72 degrees Fahrenheit). Some of the most popular hard fats, oils and butters are beef tallow, lard, palm oil, coconut oil, and cocoa butter.
When possible replace soft oils, or oils liquid at room temperature, such as olive oil, avocado oil, rice bran oil, and sunflower oil – with a hard oil.
Reduce the Soap’s Superfat Amount
Superfat is simply unsaponified fats and oils that remain the bar. These are often added at a rate of 1% to 5% in most batches. Three percent superfat is commonly used to both ensure all the lye gets used and the bar is mellow and has certain qualities such as moisturizing properties associated with the oil.
A superfat amount greater than 5% tends to make a bar softer – especially if a liquid oil makes up the superfat. By keeping the superfat content to less than 5% the odds having a firm, long lasting bar of soap increase significantly.
Use a Hard Oil for Superfat
Using a hard fat like tallow or lard as the superfat will help keep the bar firmer. The same is true of using coconut oil, palm oil, or cocoa butter.
The problem is that in cold process you cannot choose your superfat. The lye solution will convert whatever fats it chooses and leave the rest as superfat. However, with hot process soap making you can control the superfat type by adding the hard oil in after the saponification process is complete (while it is still very hot but before you put it in the mold).
Use a Soap Hardening Agent
Add sodium lactate at a rate of about 1 liquid teaspoon per pound of oils used in the recipe. Sodium lactate is natural. It is the sodium salt of lactic acid, so you are not adding an artificial chemical.
Although sodium lactate is created naturally in liquid form it is also available as a powder. Both versions work well.
Beeswax can also be used to naturally harden soap IF used in small amounts. About 1% of the total weight of oils in the recipe could be beeswax. I have seen it have a reverse effect when too much is used. Beeswax can also make the soap feel tacky and/or reduce lather if there is too much.
Add Fragrances in the Proper Amount
Using too much fragrance, which is a liquid, can soften soap. Just use the recommendations of a good fragrance calculator and the soap should not be too soft.
Maximizing Soap Life
Doing my own experiment, I made a batch of soap with 85% hard oils and added sodium lactate at a rate of 1 tsp per lb. of oil used. I let it cure for two extra weeks in an area with an oscillating fan and a silica water trap (people use these in laundry closets a lot).
Once ready to use – I stored the bar on a soap saver (raised pegs on a soap dish). Then, for each use, I applied the soap to a washcloth instead of using the bar directly – where I discovered something interesting…
Soap-saving Tip: Applying just a portion of the wet washcloth to the bar got the soap minimally wet while getting plenty of lather on the cloth. The resulting lather spread easily throughout the washcloth and my soap was dry again in minutes (I keep it on the tub edge between the shower curtain and liner out of habit).
Before this I had been rubbing the entire bar with the wet cloth to fill it with lather evenly. The bar still lasted about 75% longer than the previous bar. However, once I switched to minimally wetting the bar with the washcloth, the bar lasted twice as long!
In all fairness, now that I was more conscious of my soap usage, it is likely that influenced how much less soap I began using. Even so, my bar of soap now lasts more than twice as long as it used to.
Here is the summary of what changed:
- Switched to mostly hard oils (Coconut oil, Palm and Cocoa Butter)
- Used sodium lactate as a natural hardener
- Applied the soap to a washcloth instead of using it directly
- Started using a plastic soap saver that I bought at Dollar Tree (2 for $1 – the package on the right)
This was just my experience, but I can say that I went from 26 uses of my previous bar to 58 with this new bar. I was just two days shy of the bar lasting a full two months!
Full Disclosure: The last four uses came from the small bit of soap left in the bar that would normally get tossed before it tuned to a lumpy mass in the soap dish. This little bit worked well on the washcloth, but you could get the same from the lumpy mess of your bar if you let it dry out between uses.
In Closing
As you can see, making a firm bar is the best thing you can do to make your soap last as long as possible, without adding hardeners or changing the oils in the recipe, is to let your soap fully cure. That said, there is another post on this site that gets into great detail on the soap curing process. If you get a chance, this is full of information that can help you get the most out of your soap making experience.
Good luck and happy soaping!