October 01, 2023

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The Concepts Behind Soft Washing

The Concepts Behind Soft Washing

See also “Soft Washing Simplified” for more on using a pressure washer for soft washing

by AC Lockyer, SoftWash Systems

Read the current issue of eClean Magazine:

Twenty years ago, bleach and water was combined with surfactants, algaecides and residual inhibitors into the first soft washing solution. It was sprayed directly from an agricultural style tank sprayer to remove mildew, bacteria and other organic stains from building roofs and exteriors.

Soft washing revolutionized the roof and exterior cleaning industry by allowing more carefully metered chemical solutions to be applied to building surfaces for the benefit of cleaning that surface chemically without pressure. Because of that, in the last two decades, soft washing has become the most important change to the mobile exterior cleaning industry, since the downstream injector.

So how do you truly define soft washing?

There is quite a lot of controversy surrounding what constitutes soft washing technique and equipment. Let’s start with what soft washing can and cannot clean so that we understand what we are trying to accomplish by utilizing soft washing as a cleaning method.

Soft washing was initially created as a cleaning technique for safely removing algae stains from shingle roofs. By nature, shingle roofs are designed to make a home’s roofing structure more resistant to damage from the elements, thereby protecting the inside of the home. The shingle roofing system is made up generally of three parts: fiberglass sheets, petroleum adhesive and ceramic or stone aggregate. These shingles are placed on top of a petroleum-based tarpaper – often called “roofing felt” – which protects the wood sheeting or deck of the roof from moisture. All of this roofing anatomy quickly degrades except for the topmost and most important ingredient of a roofing shingle system, the aggregate.

Roofing aggregate is pressed into the hot asphalt- or petroleum-based adhesive on top of a shingle and it becomes a protective barrier for nature to attack and slowly eat away during a shingle roof’s lifecycle. It largely protects the roofing system from two weathering elements: rain and storms, and UV degradation. This aggregate reflects the sun’s rays from the roof and over time is designed to weather away little by little completing the service life of the shingle roof system. This, in many cases, takes over 30 years.

Some U.S. regions experience hailstorms, which strip away large amounts of aggregate from the shingle roof system, leading to decreased service life. In these cases, roofs are often replaced because of loss of vale from the roof system.

Pressure washers are a mechanical duplication of this natural attack on a shingle roof system. Shingle roof manufacturers recognize this and have, in many cases, written into their warranties that any pressure washing of a shingle roof will void the manufacturer’s warranty.

Addressing this concern is what drove the invention of soft washing. Soft washing is actually much more closely associated to pest control than to the pressure washing industry. In fact, when I developed soft washing back in 1991, I had been involved in the nursery industry, growing and marketing ornamental plants for seven years. I took my degree in horticulture and my experience treating plants for fungal and bacterial infections and applied it to rooftop staining issues. In 1991, that experience and training was used to develop the first completely chemical roof cleaning system, the Mallard System.

The Mallard System

The Mallard System treated rooftop infestations like a pest, not a stain,by treating the issue at the root of the problem by actually killing the rooftop fungus and leaving behind inhibitors to aid in keeping the fungus from coming back.Many believe that merely spraying a bleach-and-water solution on a roof’s surface will achieve a thorough and lasting cleaning result. It will not.

Though many soft wash solutions contain some sodium hypochlorite (bleach), that bleach alone will not obtain a 100 percent kill ratio against rooftop microbes which cause staining. In a true soft washing application, bleach is only used to achieve two things: to aid the soft-washing pro in determining what surfaces have been treated thoroughly, and to create an instant clean effect. In actuality, most of the algae, mold, mildew and bacteria is left behind on the surface and is now just bleached clear. Rain and other weathering elements will remove the dying microbes later.

In time, as I cleaned more and more roofs, this soft wash cleaning solution dripped down onto driveways, wood fences, soffits, pool decks and more. I began to see the potential for cleaning other surfaces. What was conceived as an answer for safely and effectively cleaning roofs was now seen as a way to perform maintenance cleanings throughout a homeowner’s or businesses’ property on many surfaces.

Soft washing became a quick and effective way to treat and clean away any organic-based stain from a building’s surface, especially where pressure washing would damage roofs, paint, wood, EAFIS or other delicate surfaces. The list of building infestations and stains began to grow. Mold, mildew, algae, fungus, bacteria, viruses, germs, mosses, lichens, insects, organic soiling and more were easily removed with the soft washing technology. That explains the why and the what.

Now to truly understand the technique you have to understand some background I have already touched on. In 1984, I began my high school corer as the son of a high school dropout that became a super entrepreneur. My father was a very successful businessman who owned and sold several successful service businesses. I entered high school with no real desire to graduate or excel and was mostly concerned with growing my hair out, playing in bands and chasing girls. My sophomore year, I was 16 and READY to drop out and join the family business. I had started my first semester, had an elective that I hated, and was still within the window transferring to another class. The only other elective open was a Horticulture 1 agriculture class. Well anything was better than what I was in so I gleefully transferred into Hort 1.

That class came with an opportunity to join the Future Farmers of America, and my teacher thrust me into being one of the chapter’s officers. That changed my life’s direction forever. By the time I graduated from high school, I was blessed with many FFA honors. Simultaneously – through dual enrollment ag classes, high school classes, local ag and nursery jobs, and FFA leadership – I gained a degree in horticulture that included 720 hours of instruction.

Basically, when I saw what was growing on roofs, I only saw one way to attack it – the same way we attacked the same microbes growing on plants. Spray it!

So soft washing technique is based strongly in the spray-and-kill-it approach. The application of a chemical to kill an alien invader. The inoculation for the virus. The cure for the disease. Soft washing is and will always be the application of a chemical to a surface where the chemical does all of the killing and cleaning of the microbe. Soft washing chemicals need only be applied to clean. No pressure is needed for the cleaning, only for the application. Any where the chemical can reach will be cleaned by the chemical. The chemical is not selective. It cleans whatever it comes in contact with.

Soft Washing Equipment

In the same way you cannot treat simply half of a home to cure a roach problem, you cannot treat just half a roof or half a wall to achieve any kind of lasting result against these microbial invaders. Soft wash solutions go deeper than just the surface of the building material and/or roof; it seeps into every crevice and pore. That’s why it can last up to four to six times longer than pressure washing.


The simplest soft washing rig consists of just a few parts: the tank, the pump, the hose and finally the spray gun. There are more sophisticated configurations available, allowing for more options and wider mixes of differing soft wash solutions, but the typical tank sprayer will work nicely. You know you are soft washing when your spraying system has everything to do with delivery of the soft washing chemicals and nothing to do with the cleaning of the surface itself. Soft wash systems merely deliver a potent mix of chemicals that treat the building exterior surface and the chemical does all of the cleaning, removing the organic based stain.


Beyond understanding what soft washing actually is, now we all need to understand that careful chemical choices need to be made while soft washing. Biodegradable chemicals are available making soft washing even more environmentally responsible. Soft washing, because of its long-lasting clean, allows a surface to stay clean with less frequent visits from the cleaning company, further reinforcing less visits, meaning less water and less chemicals. In soft washing, less is definitely more when it comes to being good stewards of our environment.

Soft washing is becoming a preferred way to perform maintenance cleanings while implementing good environmental stewardship guidelines. Soft washing shouldn’t be ignored. You can either buy a ticket or you can stand on the track,s but one way or another this train is going to impact your life. Why not let it be a positive impact to your bottom line?

AC Lockyer is the former owner of Mallard Systems and TerraClean where he was responsible for sales in excess of $27 million dollars in soft washing. He was awarded the Florida 100 in ‘99 & ‘00 as well as the Central Florida Up & Comers Award in 2001. AC enjoys fishing and in 2006 won the Redfish Tour National Championship. AC is a husband and a father to his two children. AC now owns SoftWash Systems a company dedicated to supplying equipment, chemicals, education and support to the soft wash professional.

Click here for more soft washing related articles.

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