How Long Does Melt And Pour Soap Base Last?

Melt and pour soap base is a ready-made soap base that can be melted, customized with colors and scents, and poured into molds to create finished soaps. It is made by soap manufacturers using a process called saponification, where oils and fats are combined with a strong alkali solution like sodium hydroxide to produce a soap base. The resulting substance is then molded and cooled to form a solid block. This premade soap base contains glycerin for moisturizing properties and is very easy to work with compared to making soap completely from scratch.

The shelf life of melt and pour soap base depends on several factors like the ingredients used, storage method, water content, and whether any additives are added. Properly stored, high-quality melt and pour soap can last up to a year before losing its freshness and scent. This article will examine these key factors that determine how long melt and pour soap lasts.

Table of Contents

Ingredients

Melt and pour soap base is made up of a few key ingredients that affect its longevity. The main ingredients are oils, fatty acids, glycerin, and water:

Oils – The types of oils, like coconut, palm, olive, or shea butter, determine the fatty acid content. Fatty acids moisturize skin but can go rancid over time. However, melt and pour contains minimal unsaturated fatty acids so rancidity is not a concern.
Fatty acids – Saturated fatty acids like stearic and palmitic acid help harden the soap base and contribute to a longer shelf life. Unsaturated fatty acids like oleic acid are prone to rancidity but minimal in melt and pour.
Glycerin – Glycerin is a humectant that attracts moisture. High glycerin content, usually 20-25%, helps keep melt and pour soft and prevent it from drying out quickly.
Water – Water makes up about 30% of melt and pour soap. Over time, the water evaporates causing the soap to dry out.

The combination of ingredients gives melt and pour soap 1-2 years of shelf life if stored properly. Glycerin content is especially important for flexibility and moisture retention (Soapmaking Forum).

Storage Method

Proper storage is key for extending the shelf life of melt and pour soap base. The base should be stored in a cool, dry place in an airtight container. Exposure to heat and humidity causes the base to sweat and lose moisture over time. According to From Nature With Love, melt and pour soap base has a shelf life of 1-2 years if stored properly.

Storing the soap base in an airtight plastic container or ziplock bag prevents moisture loss. Make sure to press out any air before sealing the container. The soap should be stored at room temperature or slightly cooler. Avoid temperature extremes. Refrigeration can cause sweating and humidity. Freezing may alter the texture.

As mentioned on the Soap Making Forum, the soap base will last longer if Divide large blocks into smaller portions and only open the storage container when needed. This prevents excess air exposure each time the soap is accessed. With proper storage methods, the shelf life can be extended beyond the typical 1-2 years.

Water Content

The water content of melt and pour soap base greatly impacts its shelf life. Soap bases with higher water content tend to have a shorter shelf life, while those with lower water content last longer before expiration. According to www.fromnaturewithlove.com, the moisture content of melt and pour soap base is a key factor in determining shelf life. Bases with higher water content are more prone to bacterial growth over time.

Specifically, bases with 20% or more water have a shelf life of up to one year, while those with 14-18% water can last 1-2 years. Low moisture bases with only 12% water may last 2 years or longer before expiring. So when choosing a melt and pour soap base, opting for one with lower water content can extend its usable life significantly.

Additives

Certain additives can impact the shelf life of melt and pour soap. Ingredients like milk, yogurt, citrus essential oils, and fresh juices contain enzymes that will accelerate trace and cause your soap to go bad more quickly. The sugars and proteins in these additives provide food for bacteria and mold to grow.

According to From Nature With Love, “The more additives you include in your finished product, the faster it will start to lose quality.” They recommend using 0.5-1 ounce of additive per pound of soap base and avoiding fresh dairy, juices, and fragile essential oils if you want your soap to last over a year.

Candle Science also cautions that “soaps with additives like oats, flower petals, or fruity purees will have a shorter shelf life.” The oils and sugars in these ingredients can go rancid over time. Refrigerating your soap after making it can help slow this process down.

In general, melt and pour soap with minimal additives or just botanical elements like dried herbs will have the longest shelf life. Prioritize gentle additives and make sure to store finished soaps properly if you want them to maintain quality for 1-2 years.

Best By Date

Melt and pour soap bases typically have a best by date printed on the packaging from the manufacturer. This is the manufacturer’s recommendation for how long the soap will stay fresh and perform at optimal quality. On average, unopened melt and pour soap bases will last 1-3 years past the best by date before starting to lose quality.^[1]

Once opened, melt and pour soap should be used within 6 months to a year for best results. After opening, exposure to air causes the soap to lose moisture over time. So proper storage after opening helps prolong its shelf life.

While melt and pour soap won’t ever go truly bad or become unsafe to use, it will start to lose lather and get drier and more brittle past its best by date. At that point, it’s recommended to replace old soap base with fresh stock.

Signs of Expiration

There are a few signs to watch for that indicate your melt and pour soap base is past its prime:

Drying Out

One of the most common signs is the soap drying out and becoming brittle or crumbly. This happens as the soap loses moisture over time. Older soap bases may crack or break when you try to cut or mold them.

Color Changes

You may notice the color of the soap base change, especially white bases turning a yellowish tinge. Some fragrances can also accelerate color changes. These aesthetic changes don’t necessarily make the soap unsafe, but indicate it is older.

Smell Changes

Fragrances and essential oils will fade over time in melt and pour soap. If the soap no longer smells like it did originally, that’s a sign it has aged. An unusual or unpleasant smell could indicate spoilage.

Mold Growth

If you see fuzzy mold growing on the surface of the soap base or spotting inside, it has definitely expired and should be thrown out. Mold indicates contaminants got into the soap.

Safety

Just because melt and pour soap base has expired does not necessarily mean it is unsafe to use. Properly formulated melt and pour soap contains ingredients that inhibit bacterial growth. However, one should still monitor old soap base for signs of mold, which can develop in moist soap over time. The appearance of black, blue, green, or white fuzz or spots indicates mold is present. If you see this, discard the soap base immediately. Mold can release spores that could cause an allergic reaction.

Outside of mold growth, using soap base that is past its prime may result in poor lathering or ineffective cleaning. But the ingredients themselves remain safe to use. A drop in quality is the primary risk of using expired melt and pour soap base, not a health hazard.

Extending Shelf Life

The shelf life of melt and pour soap base can be extended by ensuring proper storage conditions. According to From Nature With Love, melt and pour soap should be stored in a cool, dry place away from light and heat. Temperatures between 60-80°F are ideal. Humidity should be kept low to prevent excess water absorption.

Adding antimicrobial essential oils like tea tree, thyme, oregano, or lemon can help inhibit bacteria growth and extend shelf life. According to research from the University of Coimbra in Portugal, thyme and oregano essential oils showed strong antimicrobial activity ^[1]. Lemon and tea tree oils also exhibit antimicrobial properties ^[2].

Melt and pour soap base contains a high percentage of propylene glycol and sorbitol which help minimize water content. Keeping water absorption low will help prevent bacterial growth. Adding clay, honey, or sugar may help bind excess moisture.

When to Toss

There are a few clear signs that indicate when it’s time to discard your melt and pour soap base:

Signs of expiration – If your melt and pour soap base develops an unpleasant or rancid odor, changes color, becomes grainy, or simply doesn’t harden anymore, it’s gone bad and should be tossed. These are indications that oils in the soap base have oxidized or gone rancid.

Over 3 years old – Most melt and pour soap bases have a shelf life of 1-3 years when stored properly. If your soap base is over 3 years old, it’s best to discard it even if there are no obvious signs of spoilage.

Major formula or texture changes – If you notice major changes in the look, feel, scent, or consistency of the melt and pour base compared to when you first purchased it, that likely means it’s no longer usable. Significant formula separation or drying out are red flags.

It’s better to be safe and start fresh with a new batch of melt and pour soap base if you notice any of these signs. Rancid or spoiled soap base can cause skin irritation and make for an unpleasant handmade soap experience.

Sources:

https://www.soapmakingforum.com/threads/expired-melt-and-pour-help.91268/

https://www.newdirectionsaromatics.com/blog/products/all-about-melt-and-pour-soap-bases.html