- Homepage for the Wine Industry

Fighting Mold Fungus and Mildew on Wine Storage Tanks with Antimicrobial Coatings

Posted on December 04, 2018

by Rebecca Dolton, Regional Market Segment Director – Food and Beverage/Pharma, and Casey Ball, Regional Market Segment Director – Flooring, both from Sherwin-Williams Protective & Marine Coatings

In the wine industry, image is everything. Ornate labeling entices enthusiasts to make purchases. Prestigious names help to sell bottles. And pristine production facilities demonstrate the care that goes into crafting a fine wine.

Because image is so important, a winery’s reputation can take a hit if visitors notice signs of uncleanliness. For example, winery tour participants will quickly be turned off by the sight of mold, fungus and mildew on the exteriors of wine storage tanks, chillers and other structures. This unappetizing sight may be enough for visitors to question the quality of the wine, forgo a purchase and even skip the best part of the tour – the tasting.

Wine storage tanks and surrounding structures are particularly prone to mold, fungus and mildew growth due to their location in high-moisture environments with plenty of organic matter to feed microbes. Even the yeasts and sugars from fermenting wine can enter the surrounding atmosphere and encourage microbial growth on equipment surfaces. Affected structures are unsightly and a turnoff to consumers – even though the organic growth may have no impact on the wine’s quality.

With microbial growth presenting serious image problems, wineries must clean affected structures frequently. The process typically involves the use of chemical cleaning agents, such as bleach, to kill surface microbes. It also requires copious amounts of water to mix with the cleaning agents, blast off contamination and rinse the structures. The practice is necessary to keep structures looking fresh. However, most wineries are cleaning their equipment too often, using too much water and chemicals and unnecessarily raising their maintenance costs due to their choice of coatings for their structures.

Wineries can reduce their cleaning needs by applying antimicrobial coatings to storage tanks and other structures. The coatings resist film attack by mold, fungus and mildew by preventing microbes from penetrating into the coating and taking root. This protective barrier allows workers to easily wash superficial dirt and fouling away. By mitigating microbial growth, antimicrobial coatings enable wineries to reduce their water and cleaning chemical use – and, therefore, their total cost of ownership for maintaining structures. In addition, the coatings are resistant to alcohol-based fumes, including ethanol and wine alcohol, as well as hot oils, grease and even birds, providing added durability that can further extend maintenance cycles and reduce costs.

Reducing Cleaning Times Using Less Water and Chemicals

Cleaning microbial growth from a 40-foot-tall, 650,000-gallon wine storage tank, for example, can be a lengthy process that wineries can’t always handle in-house due to the required equipment and time investment. Using a lift, cleaning agents and pressure washers, a three- to four-man crew may average about two hours to clean the tank. The crew will first spray exterior surfaces to remove contaminants, followed by applying a solution of approximately 50% cleaning agent and 50% water. After allowing that solution to penetrate microbial growth, the crew will then use a high-pressure tip to rinse the tank. If the microbial growth is persistent, the crew may need to reapply chemicals and rinse the tank again.

Wineries most often clean tanks and other structures on a reactive basis, scheduling cleanings when microbial growth is visible or when they must comply with food safety standards. They can rarely clean tanks proactively to prevent mold growth altogether. Fortunately, though, mold is predictable. It begins to grow as structures become coated with dirt, dust and other contaminants that provide food for microbes. That growth begins to accelerate during the crush season in late summer and fall as harvesting equipment stirs up more organic contaminants into the air. Microbial growth then proliferates in late fall due to increased rain and cooler temperatures.

Ideally, wineries should clean structures before cooler temperatures arrive and accelerate microbial growth. This is not always possible, making cleaning more time-consuming and potentially increasing the use of cleaning agents to treat stubborn microbial growth. However, by applying an antimicrobial coating like Sherwin-Williams EnviroLastic® 8350 to the exterior of structures, wineries can reap the benefits of this protective coating and reduce their cleaning needs. The coating prevents microbes from penetrating into its surface and allowing the roots of growing molds, fungi and mildew to weaken the coating. Therefore, lower-pressure washing and lighter chemical treatments are sufficient to remove the surface growth. Microbes will still grow on contaminants found on the surface of structures coated with the antimicrobial coating, but crews will be able to clean those structures faster, while using less water and chemicals. That two-hour average to clean a 650,000-gallon tank may drop significantly, adding up to large maintenance savings.

Combatting Microbial Growth

Adding an antimicrobial coating to a tank exterior can take place when installing a new tank or rehabilitating an existing tank. When starting from scratch for a stainless steel tank, applicators will first pressure wash the tank’s exterior to remove any contaminants. Next, they will typically apply a direct-to-metal primer to the steel, install foam insulation over that and then prime the insulation layer before topcoating it with an antimicrobial coating. For both new and existing carbon steel tanks, as well as existing stainless steel tanks, applicators will typically pressure wash the tank exterior and then apply a primer and an antimicrobial topcoat. The processes are identical for chillers and associated piping and structures.

Enhancing Winery Operations

Switching from traditional coatings to antimicrobial coatings is a simple step for wineries that can be integrated into regular maintenance schedules or planned proactively during new equipment installations. The coatings will prevent mold, fungus and mildew from taking deep hold on structures, enabling crews to easily clean those structures, while reducing water and chemical use and extending maintenance cycles. Antimicrobial coatings available on the market can withstand numerous environmental factors and chemical cleaning solutions to deliver longer service lives. In addition, when used with a polyurea intermediate coat, the hard coatings can withstand pecking from birds to prevent penetration into tank insulation. Based on these properties, antimicrobial coatings can help wineries reduce their total cost of ownership for equipment maintenance, while also protecting their image at the production facility by helping assets look fresher year-round.

About the Authors Rebecca Dolton is Regional Market Segment Director – Food and Beverage/Pharma for Sherwin-Williams Protective & Marine Coatings. She has served the coatings industry for nine years and has won a Corporate Quality Award for her outstanding performance in meeting customers’ needs. Reach her at

Casey Ball is Regional Market Segment Director – Flooring for Sherwin-Williams Protective & Marine Coatings. Ball has specialized in the flooring and coatings market with the Sherwin-Williams Company for 17 years. He is a NACE-Certified Coatings Inspector and an SSPC-Certified Concrete Coatings Inspector. He can be reached at or 513-544-9931.

img 1

Copyright© 1994-2019 by Wine Communications Group. All Rights Reserved. Copyright protection extends to all written material, graphics, backgrounds and layouts. None of this material may be reproduced for any reason without written permission of the Publisher. Wine Business Insider, Wine Business Monthly, Grower & Cellar News and Wine Market News are all trademarks of Wine Communications Group and will be protected to the fullest extent of the law.