How to Prevent Dreaded Orange Spots (DOS) in Soap?

Dreaded Orange Spots (DOS) are rust-coloured patches that appear on handcrafted soap during drying or storage. They mostly signify that the soap's "superfat", or additional oils, have oxidised and gone rancid. The "dreaded orange spots" (DOS) in soap-making indicate oxidative rancidity. They usually occur when air, heat or light breaks down the bar's superfat, or fatty acids. The room stinks when these spots spread.

What Are Dreaded Orange Spots (DOS) in Soap?

Dreaded Orange Spots (DOS) are brown or orange spots that show up on soap because the oils have gone bad. DOS can also make things smell bad and change their feel, making them soft or sticky. These spots lower the quality of the soap, shorten its shelf life and make it less appealing and useful for long-term use.

What Causes DOS in Soap?

1. Old or Rancid Oils

Oils and fats in handmade soap can spoil over time, increasing the risk of DOS. Using rancid oils may result in noticeable changes in smell and appearance, affecting the soap's quality.

2. Excess Moisture & Humidity

DOS thrives on hot, moisturised soap bars. Extreme heat and humidity can degrade superfat, and the bars' inherent glycerin can suck water from the air. Hot or wet soap is bad.

3. Improper Curing Conditions

There is a significant acceleration of the DOS process that occurs when cured or finished soap is stored in environments that are hot, damp or filled with light.

4. Contaminated Equipment

Dreaded Orange Spots (DOS) are a sign that handmade soap has gone bad. DOS is caused by contaminated equipment that adds trace metals or bacteria that break down and oxidise the soap's unsaponified fats (superfat).

5. High Superfat Percentage

Higher superfat percentages in soap increase the risk of DOS, as unsaponified oils can spoil or react negatively with other ingredients, potentially compromising the soap's quality and safety.

6. Metal Contamination

Minerals in tap water or having soap cure in metals that are contaminated with iron, copper, or aluminium can speed up oxidative reactions that lead to rancidity, and DOS in soaps.

7. Poor Storage Conditions

DOS in soap results from poor storage conditions, causing rancid superfat due to heat, humidity, and sunlight exposure, leading to unpleasant odours and yellow-to-orange spots on the bar.

Common Signs of Dreaded Orange Spots in Soap

1. Small Orange Dots on the Soap Surface

Most of the time, small orange or rust-coloured dots on the soap bar's surface are a clear sign that it has DOS.

2. Unpleasant Odor

If your soap is rancid or DOS, it will have a bad, musty, or "off" smell that will clash with or overpower your original scent.

3. Sticky or Soft Areas

The part of the soap that has DOS may feel a little slippery, sticky, soft, or wet compared to the rest of the dry bar.

4. Discoloration Spreading Over Time

Over time, the soap will get blemishes, spots, or streaks that range in colour from light yellow to orange to deep rust or brown.

Which Soap-Making Ingredients Increase the Risk of DOS?

1. Oils Prone to Oxidation

Soap containing easily oxidized oils is prone to Dreaded Orange Spots (DOS), due to unsaturated fatty acids breaking down with oxygen exposure, resulting in unstable molecules, yellow-orange spots and unpleasant odors.

2. Expired Carrier Oils

Old or expired carrier oils increase the likelihood of Dreaded Orange Spots (DOS) in soap due to their chemical breakdown over time, making them less stable and more prone to spoilage.

3. Certain Additives or Botanicals

Food-based additives in soap can introduce fats, sugars and heavy metals. Ingredients like fruit purees, goat milk, and leafy green colorants contribute to superfat and oxidation due to natural compounds.

4. Water Quality Issues

The water you use can quietly add contaminants that make soap go bad faster. Minerals like copper and iron are often found in large amounts in tap or well water. These minerals quickly oxidise oil.

How to Prevent DOS in Soap?

1. Use Fresh Oils and Butters

Old oils and chemicals cause DOS. Use fresh oils, butters, and newly dried plant materials. Experiment with new additives in small amounts to avoid dreaded orange spots in soap.

2. Add Antioxidants (ROE, Vitamin E)

Rosemary Oleoresin Extract (ROE), Vitamin E, and Sodium Citrate are all natural or man-made antioxidants that can be added to your soap mix to slow down oxidation.

3. Maintain a Proper Curing Environment

To protect your soap from DOS, cure it properly, avoid metal storage, ensure air circulation on the rack and refrain from using plastic bags for storage. Keep it weather-safe.

4. Reduce Excess Humidity

Reducing humidity prevents Dreaded Orange Spots (DOS) in soap by slowing lipid breakdown. Lower humidity allows proper water evaporation during curing, preventing soap from absorbing moisture and preserving fats.

5. Use Distilled Water

Living in a dirty area can contaminate tap water, affecting oils and soap, leading to DOS. Because it is free of solids and other contaminants, distilled water is superior.

6. Clean Soap-Making Tools Properly

Keep your tools clean to avoid the dreaded orange spots, or DOS. Also, it is crucial to keep your tools and equipment clean while making DIY soaps to prevent the contamination of new batches with old oils.

7. Store Soap Correctly

Store the soap in a cool, dry place with good air flow while it cures. Rotate the soap so that no part of it stays closed off for long periods of time.

How to Store Handmade Soap to Prevent Orange Spots

1. Ideal Temperature & Humidity

Dreaded Orange Spots in handmade soap result from unreacted oils oxidizing. To prevent them, cure soap in a cool, dry area with temperatures between 15-25°C, and humidity below 50%.

2. Airflow During Curing

Ensuring proper airflow during soap curing prevents orange spots (DOS) caused by fat oxidation. Excess moisture can lead to rancidity, making airflow crucial for maintaining quality in homemade soap.

3. Proper Packaging Methods

Package your soap correctly, make sure it's fully hardened, use plastic that lets air pass through, like open glassine paper or bands with holes in them and keep the bars in a cool, dry, dark place.

4. Avoiding Direct Sunlight

Store handmade soap in a cool, dark, dry area with airflow to prevent orange spots. Avoid heat, humidity, and sunlight; use cardboard boxes, paper bags, or wire racks for curved bars.

Is Soap With Dreaded Orange Spots Safe to Use?

Yes, soap with mild DOS may be safe for occasional use if it only has cosmetic orange spots. However, if the soap smells rancid, feels sticky, or shows heavy discoloration, avoid using it, as rancidity can affect quality, freshness and skin experience.

Common Soap Making Mistakes That Lead to DOS

1. Using Expired Oils

Oils have a shelf life. When you blend old or almost expired base oils or butters with lye in soap-making, they will age in the soap and become bad quickly.

2. Poor Curing Setup

One of the most common mistakes that leads to DOS (Dreaded Orange Spots) is a bad curing setup. How you cure your soap is very important for whether it oxidises or goes bad.

3. Incorrect Storage

A typical soap-making mistake that causes DOS is improper storage. Keeping soap oils in wet conditions, direct sunshine, or tightly packed in plastic that doesn't let air through might spoil them.

4. Excessive Superfatting

Superfatting adds moisture to soap, but a lye discount of over 5% can leave excess unreacted oil, which may rise and oxidize, potentially affecting the soap's quality and shelf life.

5. Ignoring Oil Shelf Life

One of the main reasons why handmade soap gets DOS (Dreaded Orange Spots) is that people don't pay attention to how long their oils last.

Conclusion

Dreaded Orange Spots (DOS) in soap are mainly caused by rancid oils, excess moisture, poor curing, contamination and improper storage. Preventing DOS starts with using fresh ingredients, maintaining clean equipment, controlling humidity, and storing soap in cool, dry conditions. Proper curing and antioxidants can also help extend shelf life. For soap makers, careful ingredient selection and storage practices are essential to creating high-quality, long-lasting handmade soap bars.