Soap is made by mixing fat with a water solution of sodium or potassium hydroxide. Detergent properties are due to dissociation hydrolysis — water added to a substance causes both the substance and the water molecule to split into two parts. There are different types of soap, materials, and methods to make it.

Hobbyists sell decorative bars. Instead of making soap from raw materials, many home-based businesses buy “melt and pour” from a local supplier and fabricate bars making different shapes and adding texture, color, aroma, etc.

Melt and pour is made with a cold process. Oil and lye are mixed, which triggers saponification — hydrolysis ofglycerin to form salt. The result is hard soap that lathers, rinses quickly, and leaves a squeaky-clean feeling. Potassium makes a “softer” soap that requires more rinsing.

Soap must be neutral so it cleanses but doesn’t adversely affect paint. One of the earliest recipes for car wash soap was to mix 1,000 parts of corn oil to 697 parts of potash lye.

Active ingredients in “pre-soak” contain proprietary surfactant, sodium hydroxide, and tetrasodium salt of EDTA — chelating agent that neutralizes metal ions found in water-based formulations and protects against scale build-up. Low-pH soap for two-step cleaning may contain a proprietary surfactant blend, citric acid, and butoxyethanol (solvent used in liquid soap).

Besides lathering for show, soap must remove oil and mineral-based dirt over a broad range of environmental conditions. It must lubricate brushes, rinse off quickly, dry without spots, and be economical.

Car wash soap isn’t that expensive, but operators use a lot of it. For example, cleaning 75,000 cars may consume 1,140 gallons of soap. If soap cost $9.87 a gallon, total cost would be $11,250. One gallon of soap weighs about 9 pounds —a unit price of $1 a pound. The hobbyist may pay $2 or $1.56 a pound in bulk.

Operators buy products from regional brands (60 percent), bathtub blenders (30 percent), and national brands (10 percent). Car wash chemical is a billion-dollar business, fragmented, and has low barriers to entry. For example, I found a recipe for

liquid soap calling for 600 pounds of materials to make 33,000 gallons of soap. Half of this product is water.

Making batches of car wash products requires a “plant” environment where products can be made safely, of consistent quality, packaged and labeled, and warehoused.

Operators usually inventory weekly and demand products monthly. So, it’s important for operators to assess demand and order properly to avoid shortages or buying too much. Suppliers must anticipate the different needs of their customers.

Buying car wash soap isn’t like buying laundry detergent. Unless a blender is located close by, economic distance of delivery is a major issue. The reason is soap is a commodity.

Hobbyists can mark up the price of decorative soap because of value added. However, I have yet to see an express exterior with $4 base price offer “super-soap” upgrade for $2.

Instead, we see customers willing to pay extra to have a portion of their car hand prepped or buy bug juice, foam products, or clear-coat — all of which are made with “soap” but promise to “do more” than soap.

Since it is not commodities that make the big money in the car wash business, most operators need more than just soap bubbles and cheap prices.

Some chains have products specially formulated for them by blenders according to their requirements. Lacking scale to influence supply, “mom and pop” stores buy ready-made car wash products categorized by use, equipment type, and wash process.

Regardless of size, operators need suppliers that understand their needs as well as the economics and logistics of distribution and warehousing. After all, what good is a cheap price if you can’t get enough of the right products at the right time? Perhaps worse is a partial order where the most crucial item is missing or the whole order is delayed for one non-critical item.

Speed of distribution and accuracy requires best practices. The soap supplier you work with should be able to prioritize your receipts, manage returns, and make adjustments for your operation based on seasonal needs.

Bob Roman is president of RJR Enterprises – Consulting Services ( You can reach Bob via e-mail at