Professional pressure washers use six core chemicals on the job: sodium hypochlorite (SH) as the primary cleaning and disinfecting agent at 10–12.5% concentration, a surfactant to improve dwell time and cleaning action, an industrial degreaser for oil and grease stains, oxalic acid as a rust remover, a bleach neutralizer to protect vegetation and equipment, and a gutter brightening product for tiger stripe removal. SH is the backbone of the industry — it kills mold, mildew, algae, and bacteria through oxidation. Professional-grade SH at 10–12.5% is 2–4 times stronger than household bleach (3–6%), costs approximately $2–$3 per gallon in bulk, and is never used at full strength. Proper dilution ratios range from 1–2% for house washes to 3–6% for roof cleaning and heavy concrete work.
Mike Vidan walks through every chemical he carries on the truck and when to use each one.
| Chemical | What It Does | Pro Strength | Used On | Cost |
|---|---|---|---|---|
| Sodium Hypochlorite (SH) | Kills mold, mildew, algae; disinfects | 10–12.5% | Houses, roofs, concrete, fences | $2–$3/gal bulk |
| Surfactant | Increases dwell time; traps dirt | 1 oz per gallon of solution | Roofs (always), houses (optional) | $15–$30/gal |
| Industrial Degreaser | Breaks down oil, grease, grime | Varies by product | Driveways, garage floors, dumpster pads | $20–$50/gal |
| Oxalic Acid | Removes rust stains | Varies by product | Concrete, siding, pavers | $15–$40/gal |
| Bleach Neutralizer | Protects plants and equipment from SH | Ready to use | Vegetation, trailers, pumps, hose reels | $10–$25/gal |
| Gutter Brightener | Removes tiger stripes from gutters | Varies by product | Anodized aluminum gutters only | $20–$40/gal |
Sodium hypochlorite is the main chemical used in professional pressure washing and soft washing. It is the backbone of the industry. SH kills mold, mildew, algae, lichen, and bacteria at the cellular level through oxidation — it strips electrons from organic matter until cell walls collapse. This is why SH does not just remove stains. It sanitizes the surface and delays regrowth in a way that water pressure alone never will.
Professional-grade SH ships at 10–12.5% concentration. This matters because the household bleach on a store shelf tops out at 3–6% and is loaded with stabilizers, thickeners, and fragrances that gum up equipment and produce inconsistent results. Pros buy SH in bulk from chemical suppliers or pressure washing supply houses at approximately $2–$3 per gallon. It is not available on retail shelves at professional strength.
A surfactant mixed with SH serves three purposes: it helps the chemical cling to vertical surfaces instead of running off immediately, it traps dirt and pollutants in the water to aid rinsing, and it extends dwell time so the SH has more contact time to do its work. The standard ratio is approximately 1 ounce of surfactant per gallon of cleaning solution.
Mike Vidan’s company uses Southeast Softwash’s “Southern Drawl” as their primary surfactant. There are many professional options available. The critical rule: if you are going to use a store-bought soap instead of a professional surfactant, use a laundry detergent — never a dish detergent like Dawn. Laundry detergents are formulated to work with bleach. Dish detergents are not, and can react badly or reduce the effectiveness of the SH.
SH handles organic growth. It does not handle petroleum-based contamination. Oil stains on driveways, grease deposits on commercial concrete, dumpster pad buildup — these require an industrial-strength degreaser that attacks the contamination through an aggressive chemical reaction.
Mike Vidan’s crew carries two degreasers: “Big Dog” from LH Chemical in Savannah and “Dynamite Degreaser” from Southeast Softwash. Having a quality degreaser is essential because SH alone will not touch oil and grease stains no matter how strong the mix.
Rust stains on concrete are extremely common. They come from fertilizer runoff, iron leaching from the ground, well water with high mineral concentrations, and irrigation systems that spray mineral-rich water onto concrete and house siding. SH and degreasers will not remove rust — it requires an acid-based product.
Oxalic acid is the active ingredient in most professional rust removers used in pressure washing. Several name-brand products contain it under different labels. It chemically dissolves iron oxide (rust) from the surface. Customers with unfiltered well water feeding their irrigation system often have the most severe rust issues because the water sprays minerals across every surface the system reaches.
When cleaning roofs or siding, SH overspray and runoff inevitably contacts landscaping, plants, and grass below. A bleach neutralizer is an added insurance policy that reduces the risk of vegetation damage. It does not replace the need to thoroughly water plants before, during, and after the cleaning process — it supplements it.
Bleach neutralizer also serves a second, equally important purpose: protecting your equipment. Pressure washing is a corrosive environment. SH, acids, and chemicals eat away at trailers, trucks, hose reels, pumps, and fittings over time. Spraying down your equipment regularly with bleach neutralizer helps prolong the life of everything you own.
After washing a house, black streaks often remain on the gutters. These are called tiger stripes, and they are not surface-level stains. They are the result of a chemical reaction between the asphalt in roof shingles and the anodized aluminum of the gutters. A standard house wash — even with SH — will not remove them. The stains are bonded to the surface.
Removing tiger stripes requires a specifically formulated gutter brightening product designed to break down the bond between the asphalt residue and the aluminum. Mike Vidan’s crew uses “Gutter Guard” as their go-to product. Application varies by stain severity — some can be sprayed and rinsed, others require agitation with a brush or slightly more pressure.
| Method | How It Works | Best For | Pros | Cons |
|---|---|---|---|---|
| Batch Mixing | Mix SH + water + surfactant in a tank before application | Roof cleaning, heavy concrete | Precise control of concentration | Waste if mix is not fully used; requires measurement |
| Downstreaming | Injector on pump outlet draws chemical into water stream | House washes, general exterior | Chemical never touches pump; easy tip-switching | Limited to lower concentrations (~2.5% max with 12.5% SH) |
| Proportioner / Metering | Valve system controls SH-to-water ratio automatically | High-volume operations, soft wash systems | Consistent mix; no manual measuring | Higher equipment cost; requires calibration |
Different surfaces and stain types require different chemicals. Here is the decision process professionals follow.
Organic growth (mold, mildew, algae, lichen) requires SH. Oil and grease require a degreaser. Rust requires oxalic acid. Gutter tiger stripes require a gutter brightener. Using the wrong chemical wastes time and product while potentially damaging the surface.
Vinyl siding and painted surfaces use low SH concentration (1–2%). Concrete and masonry use medium concentration (~4%). Roof shingles with severe growth use higher concentration (3–6%). Delicate surfaces like wood require the lowest concentrations with careful dwell time management.
Downstreaming for standard house washes where lower concentration is sufficient. Batch mixing or a proportioner for roof cleaning and heavy concrete where higher concentrations are needed. Downstreaming maxes out around 2.5% applied SH strength when starting with 12.5% stock.
Always add surfactant for roof cleaning. Optional but beneficial for house washes and vertical surfaces. Standard ratio: 1 ounce per gallon of total solution. The surfactant extends dwell time and improves cleaning action without increasing chemical concentration.
Water all plants and vegetation thoroughly before, during, and after chemical application. Use bleach neutralizer as an added insurance policy on landscaping. Cover or move sensitive items. Communicate with the customer about the process. Prevention is cheaper than replacement.
Professional pressure washers use six core chemicals: sodium hypochlorite (SH) at 10–12.5% concentration as the primary cleaning and disinfecting agent, a surfactant to improve dwell time and cleaning performance, an industrial degreaser for oil and grease stains, oxalic acid as a rust remover, a bleach neutralizer to protect plants and equipment, and a gutter brightening product for tiger stripe removal on aluminum gutters.
SH stands for sodium hypochlorite, the active ingredient in bleach. Professional-grade SH is sold at 10–12.5% concentration from chemical suppliers and pressure washing supply houses at approximately $2–$3 per gallon in bulk. Household bleach is only 3–6% and contains additives that interfere with professional cleaning. SH kills mold, mildew, algae, and bacteria through oxidation and is the primary chemical used in professional pressure washing and soft washing.
For a standard house wash on vinyl siding or painted surfaces, the target is 1–2% final SH concentration. Starting with 12.5% SH, a 1:4 mix (1 part SH to 4 parts water) produces a 2.5% application strength. For concrete and masonry, approximately 4% is standard. For roof cleaning and severe organic growth, 3–6% may be needed. Always start at the lower concentration and increase only if necessary.
Household bleach at 3–6% concentration is not recommended for professional pressure washing. It is substantially weaker than professional-grade SH (10–12.5%), contains stabilizers and fragrances that can gum up equipment, and produces inconsistent results. If you are running a business, use professional-grade SH from a chemical supplier. If you must use store-bought product, never use dish detergent like Dawn as a surfactant — use a laundry detergent instead, as it is formulated to work with bleach.
Oxalic acid is the standard rust remover used in professional pressure washing. It chemically dissolves iron oxide from concrete, siding, and pavers. Rust stains are caused by fertilizer runoff, iron leaching from the ground, well water with high mineral content, and irrigation systems spraying mineral-rich water onto surfaces. SH and degreasers will not remove rust — it requires an acid-based product specifically designed for iron oxide removal.
Black stripes on gutters (called tiger stripes) are caused by a chemical reaction between asphalt from the roof shingles and the anodized aluminum of the gutters. They are not surface stains — they are chemically bonded to the metal. A standard house wash with SH will not remove them. Removal requires a specifically formulated gutter brightening product designed to break down the asphalt-aluminum bond. Application varies — some stains can be sprayed and rinsed, others require brush agitation.
The chemicals are the same — sodium hypochlorite, surfactant, and water. The difference is the application method. Soft washing uses a dedicated pump system (not the pressure washer pump) to apply higher concentrations of SH at low pressure for surfaces like roofs that would be damaged by high-pressure water. Pressure washing uses a downstream injector to apply lower concentrations of SH through the pressure washer, with the option to switch to high-pressure rinse tips. Both methods use SH as the primary cleaning agent.
Fresh 12.5% SH stored in a cool, dark, ventilated location maintains usable strength for approximately 30 to 60 days. After that it degrades into saltwater and oxygen. Heat and UV exposure accelerate degradation significantly — a drum stored in direct sunlight can lose half its concentration within weeks. Professional operators rotate inventory and test concentration with a hydrometer when a batch has been sitting.
For complete training on chemical mixing, equipment selection, application methods, and how to clean every surface on a residential job site, check out the How To Wash course at pwcourse.com.
Pressure Washing Business Owner (25+ Years) · QuoteIQ Co-Founder · 580K+ YouTube Subscribers
Mike Vidan has operated a pressure washing and soft washing business for over 25 years. He co-founded QuoteIQ, a CRM for home service contractors with 40,000+ daily users. His YouTube channel (580K+ subscribers) teaches contractors the technical and business skills needed to grow. Author of Pressure Washing Marketing Domination. Co-creator of the How To Wash training program.
Entrepreneur, service business operator, and Co-Founder of QuoteIQ. 25+ years building from the ground up.
© 2026 Mike Vidan. All rights reserved.