Antimicrobial preservatives have been used to protect life's essentials from spoilage and contamination since the beginning of time. The ancient Egyptians practiced mummification, an embalming process in which the body of an important person was treated with chemicals, allowing it to be preserved for the afterlife. Sodium chloride, a staple in almost every kitchen and more commonly known as table salt, is one of the oldest and most recognized preservatives. In early civilization, salt was used as a preservative to eliminate peoples' dependency on seasonal availability of food, and was a precious resource to those who did not have the luxury of refrigeration.

Today, biocides, antimicrobials, mildewcides, preservatives, slimicides and antifungal agents are familiar additives in numerous aqueous formulations. Marketing products that lack essential preservatives is not an option for formulators trying to maintain a cutting edge in this increasingly competitive industry. The omission of biocides in waterborne coatings can result in product spoilage, customer quality issues, product recall, product rework and downtime. Microbial degradation leads to compromised performance, including gas formation, discoloration, changes in viscosity, poor stability, loss of adhesion and foul odors - all of which can have a significant economic impact on the producer through loss of sales and even loss of reputation.

Safeguarding Aqueous Products From Microbes

Owing to their lack of organic solvents, aqueous coatings are particularly susceptible to microbial contamination. Microorganisms are most often introduced through raw materials included in the formulation itself, with water being one of the most common culprits. Outside agents, such as containers and their packaging, manufacturing equipment and the plant environment can also provide avenues for microbes to enter a formulation and cause degradation to the end product. In addition, coatings are vulnerable to air and waterborne microbial contaminants due to their exposure to humidity, and to bulk storage and handling systems. Even the user and the environment during normal use of the product can introduce contaminants.

Gram-positive and gram-negative bacteria, yeast, mold, and algae are the most common contaminants for coatings formulations - all aggressive microorganisms that utilize components of these formulations as food. The use of an appropriate in-can biocide can inhibit the growth of, or eliminate these microorganisms and increase storage life of a product. Other biocides can be used for quick clean up of contaminated wash water, latexes, mineral slurries and finished formulations. Similarly, a dry film fungicide is appropriate for protecting finished surfaces where fungal colonization can occur.

Using biocides at an early stage to prevent product spoilage is the best way to protect your investment. Contamination is often invisible until spoilage is too advanced to salvage the product.

Creating the Optimal Biocide

The most effective biocides have specific attributes, including broad-spectrum antimicrobial efficacy, ease of handling, cost effectiveness, and long-term protection that maximizes product shelf life. Other desirable features include rapid biocidal activity, lack of a strong or offensive odor, water solubility, heat stability and no microbial tolerance issues.

But by their very nature, all biocides have limitations and, as yet, no one, perfect active ingredient can solve every microbial challenge. Today, biocide manufacturers are helping customers overcome this challenge by tailoring blends and combinations of active ingredients to create optimal biocidal performance, designed for specific formulations and unique customer needs.

When combining different types of biocides - for example, a fast-acting biocide with a long-term preservative or two long-term preservatives that have complementary activities - formulators can target a broader antimicrobial spectrum and offer longer-term protection. Alternatively, biocides can be used together to create synergy, whereby lower concentrations of two actives have stronger efficacy than a higher concentration of either active alone. Because formulators may be able to reduce the overall amount of active needed, this can be a very cost-effective and environmentally friendly way to protect a product.

DOWICIL QK-20: An Effective Biocide in Combinations

On its own, DOWICIL™ QK-20 antimicrobial from Dow Biocides is a fast-acting, broad-spectrum biocide that is ideal for reducing microbiological contamination in raw materials due to its ability to act as a quick-kill biocide and as a temporary preservative in slurries, latex and resin emulsions, process water, or products such as aqueous coatings, adhesives, sizing and caulk. It quickly and economically cleans up potential sources of contamination, minimizing shutdowns or product delays. DOWICIL QK-20 can also be used to eliminate microorganisms present in solution or growing on the surface of process equipment, such as reaction vessels, storage tanks and containers, piping and hoses.

When DOWICIL QK-20 is used in combination with long-term preservatives, such as DOWICIL 96, Kathon® or CANGUARD™ BIT 20 DPG, additional benefits can be realized. For example, by reducing existing bio-burden in a formulation, DOWICIL QK-20 helps to increase the overall effectiveness of the long-term preservative, thereby reducing the chance for field failure, customer quality issues, product recall, product rework and downtime - and in some cases, overall preservative costs may be reduced.

Choosing the Right Biocide or Biocide Combination

Because no single active is the ideal biocide, combinations like the ones described can be used to optimize product performance and meet the many microbial challenges formulators face every day. But blending is not always the ideal solution, and can backfire if one of the active ingredients becomes deactivated in the presence of another. A trusted biocides solutions provider with knowledge of combinations, blending and biocide synergy can help a formulator or manufacturer optimize product performance and efficacy.

These experts will help customers analyze their unique situation and formulation issues and guide them toward the ideal biocide solution. To determine the best treatment option, they may use advanced testing methodologies like TAUNOVATESM high-throughput microbiological testing capabilities from Dow Biocides.

A completely automated protocol, TAUNOVATE provides the ability to rapidly determine the microbial status of a formulation, as well as effectiveness of the biocide product or products being used in it, and can be used with any industry-standard test method including ASTM and IBRG (International Biodeterioration Research Group; www.ibrg.org/index.htm) tests. Its increased qualitative accuracy rapidly determines the microbial status of a formulation as well as the effectiveness of the biocide products being used. The improved efficiency and accuracy of the technique works to streamline the biocide specification and treatment processes. It allows a wide variety of biocide options to be tested quickly, including different concentrations of the existing biocide, other biocide products and combinations of biocides. Upon completion of the testing, customers are left with a comprehensive analysis of the best balance between economics and performance of their biocides.

Development of new, high-performance products can create lucrative market opportunities for companies, but can also create significant formulation challenges. With superior laboratory capabilities, regulatory expertise and a deep understanding of chemical compatibility, Dow Biocides will ensure that our customers' products remain successful and competitive in the market and help you select the optimal biocide or biocide combination when developing a formulation.

For more information, visit www.dowbiocides.com.