A
Acid Wash
An acid wash in exterior cleaning is the application of a dilute acidic solution — most commonly muriatic (hydrochloric), phosphoric, oxalic, or a proprietary masonry blend — to dissolve mineral-based…
Process & MethodsAlgae vs. Lichen
Algae (most commonly Gloeocapsa magma on roofs) is the photosynthetic organism responsible for the black streaks running down asphalt shingles, the green haze on north-facing siding, and the slippery…
Stains & ContaminantsAlkaline Cleaner
An alkaline cleaner is a high-pH detergent (typically pH 10-14) that dissolves oil, grease, fats, protein stains, and atmospheric grime by saponifying fatty acids and emulsifying petrochemical contami…
Chemicals & DetergentsAnti-Slip Treatment
Anti-slip treatment is a chemical process — sometimes followed by a mechanical treatment — that increases the coefficient of friction on hard-surface flooring to reduce slip-and-fall risk when the sur…
Process & MethodsAtmospheric Fallout
Atmospheric fallout is the general term for the mix of airborne particles that settle on your home over time: diesel soot from trucks and buses, combustion residue from industrial areas, pollen, road…
Stains & Contaminants
C
Cavitation
Cavitation is the formation and violent collapse of vapor bubbles inside a pressure washer's pump when the water supply is insufficient, the inlet is restricted, or the water temperature is too high.…
Science & MeasurementChelating Agent
A chelating agent is a chemical that grabs onto metal ions — calcium, iron, copper, magnesium — and holds them in solution so they can be rinsed away instead of bonding to a surface. The word comes fr…
Chemicals & DetergentsChem Ratio
Chem ratio refers to the final dilution of cleaning chemistry at the surface — the percentage of active ingredient after the downstream injector, surfactant, and rinse water have all combined. For sof…
Chemicals & DetergentsChimney Cap
A chimney cap is the metal (stainless, copper, galvanized, or aluminum) or cast-stone hood that sits on top of the flue, typically with a mesh screen on the sides. It serves three functions: it keeps…
Building ComponentsConcrete Sealer
A concrete sealer is a penetrating or film-forming coating applied to cleaned, dry concrete to reduce its absorption of oil, road salt, staining agents, and water. Penetrating sealers (silane, siloxan…
Chemicals & DetergentsCrown Coat
A crown coat is the sloped mortar or cement cap that sits at the top of a masonry chimney, surrounding the flue tile(s). It is not the decorative cap piece (that's a chimney cap) — it is the poured or…
Building Components
D
Damp Proofing
Damp proofing is the application of a moisture-resistant coating or membrane to a masonry surface — most commonly foundation walls, brick veneer, and chimneys — to slow water absorption and reduce eff…
Building ComponentsDeionized Water
Deionized water — often shortened to DI water — is water that has had essentially all of its dissolved mineral ions removed by passing it through specialized ion-exchange resin beads. Positive-charge…
Science & MeasurementDownspout Extension
A downspout extension is a length of corrugated plastic pipe or aluminum channel attached to the bottom of a downspout outlet to direct water away from the foundation of the house. Standard downspout…
Building ComponentsDownstream Injector
A downstream injector is a small one-way check valve installed on the low-pressure outlet of a pressure washer pump that automatically draws cleaning solution from a bucket whenever a low-pressure noz…
Equipment & TechniquesDownstreaming
Downstreaming is the technique of injecting soap or cleaning solution into the pressure washer's water line on the low-pressure side of the pump — downstream from the pump, hence the name. A chemical…
Equipment & TechniquesDrip Edge
Drip edge is an L-shaped or J-shaped metal flashing installed along the eaves and rakes of a roof to direct water off the roof edge cleanly and away from the fascia board and underlying structural com…
Building ComponentsDustless Grinding
Dustless grinding is the use of a HEPA-filtered vacuum attached directly to a grinder, sander, or surface prep tool to capture dust at the source before it can become airborne. Traditional grinding —…
Process & MethodsDwell Time
Dwell time is the interval between applying a cleaning chemistry to a surface and rinsing it off. It is the single most misunderstood variable in exterior cleaning. Chemistry does not clean instantly;…
Process & Methods
G
Gloeocapsa Magma
Gloeocapsa magma is a photosynthetic cyanobacteria that feeds on the limestone calcium carbonate filler embedded in asphalt shingles. It is the organism responsible for the black or dark-gray streaks…
Stains & ContaminantsGPM (Gallons per Minute)
GPM stands for Gallons Per Minute — the volume of water a pressure washer delivers per minute of operation. While PSI gets the headlines, GPM is what actually does the cleaning. Think of it this way:…
Science & MeasurementGutter Apron
A gutter apron is a flat metal flashing — typically galvanized steel or aluminum — installed under the first course of shingles at the roof edge and bent down into the back of the gutter. It creates a…
Building ComponentsGutter Guard
A gutter guard is any cover, screen, insert, or hood system installed over or inside gutters to reduce the amount of debris that enters the trough and clogs the downspouts. There are five main categor…
Building Components
H
Hard Water Stain
A hard water stain is the crystalline mineral deposit that forms on glass, metal, and stone when water high in dissolved calcium, magnesium, iron, or silica evaporates and leaves its dissolved mineral…
Stains & ContaminantsHot Water Pressure Washing
Hot water pressure washing uses a diesel-fired burner to heat the pressure washer's output to 180-200°F before it hits the surface. The physics is simple: hot water dissolves grease and oil, accelerat…
Equipment & TechniquesHydrophobic Coating
A hydrophobic coating is a chemical treatment applied to a surface that causes water to bead and roll off rather than spreading and sheeting across it. The term derives from the Greek for "water-feari…
Chemicals & Detergents
M
Mildew vs. Mold
Mildew and mold are both fungi, but they behave differently. Mildew is a flat, surface-level growth — usually white, gray, or yellowish — that stays on top of a substrate and can typically be cleaned…
Stains & ContaminantsMildew vs. Mold
Mildew and mold are both fungi, but they differ in how they grow, where they appear on exterior surfaces, and how they respond to cleaning chemistry. Mildew is the surface-level, flat, gray-to-white g…
Stains & ContaminantsMoss vs. Lichen
Moss and lichen are both organisms that colonize roofs and exterior surfaces in Wisconsin, but they are biologically distinct and require different removal strategies. Moss is a non-vascular plant tha…
Stains & Contaminants
O
Organic vs. Inorganic Stain
Organic stains are caused by living or once-living things: algae, mold, mildew, lichen, tannins from leaves, berry drip, insect excretion, pet urine, and so on. They contain carbon and respond to oxid…
Stains & ContaminantsOxalic Acid
Oxalic acid is a naturally occurring organic acid (found in rhubarb, spinach, and many woods) that is widely used in exterior cleaning as a rust stain remover, wood brightener, and mineral deposit tre…
Chemicals & DetergentsOxidation
Oxidation is the chemical reaction between a surface and oxygen (plus UV light, moisture, and time) that produces a chalky, faded, or dulled appearance. On vinyl siding, oxidation shows up as a powder…
Stains & Contaminants
P
Paver Polymeric Sand
Polymeric sand is a mixture of graded sand and polymer binders that, when moistened and compacted, hardens into a firm-but-flexible joint filler between pavers, bricks, and stone. Unlike regular sand,…
Building ComponentsPercarbonate
Sodium percarbonate is a solid granular compound that releases hydrogen peroxide and soda ash when dissolved in warm water — essentially an oxygen-based bleach. Unlike chlorine bleach, percarbonate do…
Chemicals & DetergentsPollen & Honeydew
Pollen and honeydew are two separate sticky contaminants that are constantly blamed on each other. Pollen is the yellow dust that coats Wisconsin cars, siding, and windows every spring from late April…
Stains & ContaminantsPolymer Sealer
A polymer sealer is a protective coating applied to a cleaned and dried surface — glass, concrete, wood, metal, brick — that forms a long-molecule chain on the surface to repel water, dirt, and staini…
Chemicals & DetergentsPost-Treatment
Post-treatment is any chemistry or protective step applied after the primary cleaning to neutralize residual cleaning agents, extend the result, or seal the surface against future staining. On wood de…
Process & MethodsPoultice
A poultice is a paste-like cleaning compound applied to a porous surface — natural stone, unsealed concrete, brick, limestone — to draw a stain out of the pores through capillary action. The paste is…
Process & MethodsPre-Treatment
Pre-treatment is the application of a cleaning chemistry to a surface before the primary wash — typically to break down, dissolve, or kill a specific stain or organism before pressure or soft-wash tec…
Process & MethodsPressure vs. Volume
Pressure (PSI) and volume (GPM) are the two fundamental outputs of a pressure washer, and understanding the tradeoff between them is the single biggest step an amateur can take toward professional-lev…
Science & MeasurementPSI (Pounds per Square Inch)
PSI is the unit of pressure used to rate pressure washers, measuring the force of water exiting the pump per square inch of surface area. Consumer pressure washers run 1,500-2,500 PSI; professional ri…
Science & Measurement
R
Reverse Osmosis (RO)
Reverse osmosis is a water purification technology that uses pressure to force water through a semi-permeable membrane so fine that it blocks dissolved minerals, bacteria, and most organic molecules w…
Science & MeasurementRinse Water Management
Rinse water management refers to the planning and technique used to control where cleaning solution runoff goes during a wash job — protecting landscaping, drainage systems, neighboring properties, an…
Process & Methods
S
Screen Washing
Screen washing is the process of removing, cleaning, and reinstalling window screens during a window cleaning service. Screens accumulate dust, pollen, dead insects, and oxidation on both sides over t…
Process & MethodsSoap Distance
Soap distance is the maximum height or horizontal reach at which a pressure-washer rig can project cleaning solution through a low-pressure soap nozzle. It is a direct function of GPM, pump pressure,…
Equipment & TechniquesSodium Hypochlorite
Sodium hypochlorite (NaOCl) is the active ingredient in household bleach and the primary disinfectant used in professional soft washing. It is sold to exterior cleaners in 12.5% concentration (commonl…
Chemicals & DetergentsSodium Percarbonate
Sodium percarbonate is a granular oxygen-based bleach that releases hydrogen peroxide and soda ash when dissolved in warm water. Unlike sodium hypochlorite, it contains no chlorine, has no strong off-…
Chemicals & DetergentsSoft Wash
Soft washing is a low-pressure exterior cleaning method that uses biodegradable detergents and a controlled bleach solution to kill the algae, mold, mildew, and bacteria that cause staining — rather t…
Process & MethodsSoft-Bristle Brush
A soft-bristle brush is the wash head of a water-fed pole or the hand tool used to gently agitate a surface during cleaning without damaging the substrate. For glass, a double-row flocked nylon or hog…
Equipment & TechniquesSoft-Wash Ratio
Soft-wash ratio refers to the dilution of concentrated sodium hypochlorite (typically 12.5%) with water to achieve a target application-strength solution. The standard industry mix for house washing i…
Science & MeasurementSqueegee Technique
Squeegee technique refers to the controlled hand-motion pattern used to remove cleaning solution and water from interior window glass without leaving streaks, drips, or wet edges. A professional squee…
Equipment & TechniquesSurface Cleaner
A surface cleaner is a circular attachment — typically 16, 20, or 24 inches in diameter — that replaces the wand on a pressure washer for cleaning flat horizontal surfaces. Inside the housing, two or…
Equipment & TechniquesSurfactant
A surfactant (short for "surface-active agent") is a chemical compound that lowers the surface tension of water so it can wet, spread, penetrate, and cling to a dirty surface instead of beading up and…
Chemicals & Detergents
T
Tannin
Tannins are natural plant polyphenols — the same compounds that give red wine, tea, and oak bark their characteristic astringent flavor. In exterior cleaning, they are the source of the persistent bro…
Stains & ContaminantsTDS (Total Dissolved Solids)
TDS stands for Total Dissolved Solids — the concentration of dissolved minerals, salts, and metals in water, measured in parts per million (PPM). A TDS meter is the single most important tool in profe…
Science & MeasurementTiger Striping
Tiger striping is the pattern of dark vertical streaks that appear on the exterior face of aluminum and painted gutters, running from the gutter lip down toward the ground. The stripes are caused by e…
Stains & ContaminantsTwo-Stage Cleaning
Two-stage cleaning is the process of applying a chemical pre-treatment first, letting it dwell and break down the stain or organism, then following with a mechanical rinse (pressure wash or soft-wash…
Process & Methods
W
Water-Fed Pole (WFP)
A water-fed pole is a lightweight telescoping pole — typically carbon fiber, 20 to 45 feet long — with a soft brush and water jets at the tip, fed by a hose connected to a pure-water filtration system…
Equipment & TechniquesWeep Hole
A weep hole is a small, deliberately-placed opening at the bottom of a brick-veneer wall, window frame, or storefront glazing that lets trapped water drain out. On brick homes, weeps are typically ver…
Building Components