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Sodium hypochlorite

In the pressure washing industry, one of the main questions we get asked daily is, what chemical do you guys use? There isn’t just one answer for that question because there are various specialty chemicals used depending on what we are cleaning, but the main one by far is sodium hypochlorite. For years this was seen as a somewhat taboo subject because nine times out of ten, “bleach” would be the term used, and while sodium hypochlorite is the active ingredient in bleach, don’t expect us to spray Clorox on your home.

Uses and applications

Sodium hypochlorite is a powerful chemical that is used in water treatment, pool chlorine, hair salons, household cleaning and disinfecting, and of course, our preferred method of exterior cleaning, which is soft washing. In the case of pressure washing, it can be applied using a chemical injector and low-pressure tip on the spray gun or by adding an injector at the spray gun itself. What we use at Midtown Power Washers is a 12-volt pump, which pulls the chemical at the desired ratio and sprays onto the surface again using low pressure. It is our preferred method because we can be very exact with our ratios. All of these applications are followed with a thorough rinse to wash away the applied chemical along with the dirt and debris.

What is sodium hypochlorite?

Without getting too technical, sodium hypochlorite is the salt form of hypochlorite, which is a solid and unstable and therefore unsuitable for use by itself, after being turned into its salt form, which is a brine dissolving and turning the solid into a liquid for its multiple applications. Once in this liquid form, it absorbs into the growth and denatures the proteins in organics, and breaks them down.

Why do we use sodium hypochlorite in pressure washing?

90% of the stains or “dirt” on your home are actually organic of some type, usually falling into algae, bacteria, mold, or moss category. This, along with any insect byproducts, spider webs, wasp nest, or slug residue, can be “killed” or broken down by this solution. We use it essentially because it is the most effective product and, when used by trained professionals, the safest way to rid your home of these unsightly and sometimes dangerous growths. Pressure washing alone will not rid the home of all of this growth because inevitably, there will be spots microscopic in size that are left, when soft washing, every microscopic spore is effectively killed by the sodium hypochlorite. The only time actual pressure should be used when pressure washing is on concrete surfaces which are rated to withstand such pressure, and even then, it is mostly used to rinse away the dead growth.

Is it safe?

In short no, it is a concentrated and highly corrosive chemical that should always be applied by trained professionals. That being said there are many different concentration ratios that are used when pressure washing for the many different substrates found around your home. For instance a roof wash for standard shingle roofs would be the highest concentration that we use while soft washing. When applying we run the risk of contact with eyes and skin, (not to mention being 40 to 50 feet off of the ground). The risks to your home would be towards you landscaping, bushes, trees, grass, etc. The way we maintain what we like to call property protection in this application would be to dilute the ratio down with water while applying the chemical to your roof, once the sodium hypochlorite is diluted enough it becomes essentially harmless. This takes a lot of concentration on every detail and usually working in tandem as a two person team. When applying to something less porous like vinyl siding the chemical ratio applied is dropped significantly to the point we’re it is harmless to plants but we still use property protection there as well noting any electrical outlets or switches and covering them along with key holes, which we apply a little wd40 in after the job is completed. This isn’t necessarily because of the sodium hypochlorite but because water in general can damage these things. Even with all of the hazards of use it is still much less harmful than blasting away dirt using a 4,000psi pressure washer. Once the solution is dry in any ratio however it becomes a harmless salt which isn’t a danger at all.

Other chemicals

While sodium hypochlorite is the main chemical that we use to treat and clean organic substances there are many potential non-organic stains that could be on any structure. Here we will just run through a short list, starting with the other common chemical a surfactant or “soap” is used to be a very mild degreaser in some cases but the main reason for its use it that when it’s mixed with the water and sodium hypochlorite and then sprayed it helps the mixture stick to the substrate better and also helps with the drying time giving the technician time to rinse everything before drying. Then we have oxalic acid, which is mainly for wood brightening and rust removal. It being an acid works well with wood cleaning because of its effects as a neutralizer for the sodium hypochlorite. There are a few other acids that can be used but this is the one that we prefer. We also use sodium percarbonate for any wood restoration process. If you have ever noticed a white chalky substance near the grout lines of brick we use a two step calcite removal chemical that is made by a company called EBC, it is an acid as well. At different ratios it is used to remove the calcite or efflorescence which leaches to the surface of bricks. We use various graffiti removal chemicals depending on what the substrate underneath is but that breaks down into two categories masonry or sensitive substrates.

Our thoughts

Sodium hypochlorite has been used in cleaning since the 1700’s and we feel that the stigma around it is unfounded. Yes, it can be dangerous, it can be harmful but again that’s why you as a customer are trusting us, the professionals, to take care and manage those hazards. It is called “bleach”, “pool shock”, “chlorinating liquid”, among others but we just call it SH and we use it every day so you can rest assured that we understand and are fully capable of handling it in a safe manner around your most valued possessions, which is not something we take lightly at Midtown Power Washers. All of the other “specialty” chemicals may not be offered by every pressure washing or soft washing company but we pride ourselves on the education and knowledge to be able to identify and then safely remove any exterior stains found on properties. Again this is why you trust a professional for this line of work because the knowledge of what these chemicals do and how they interact is vital when using them.

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