Non-Ionic Surfactant
A non-ionic surfactant is a surfactant whose molecule carries no net electrical charge, making it uniquely tolerant of the extreme pH and high chlorine content found in a soft-wash mix. Ionic surfactants (anionic, cationic) often precipitate, react, or lose effectiveness when combined with 12.5% sodium hypochlorite; non-ionics stay stable, keep their foaming action, and continue to reduce the surface tension of the cleaning solution throughout the dwell period.
In depth
For exterior cleaners, non-ionic surfactants are the only realistic choice for soft-wash work. Brand names like Elemonator, Roof Snot, and Squeegee Off are non-ionic blends engineered for bleach compatibility. They thicken the mix so it clings to vertical surfaces, slow evaporation, enhance foam visibility, and improve rinse-ability. A mix of 12.5% bleach plus a good non-ionic surfactant looks completely different on the wall than plain bleach: it foams, it sticks, it stays where you put it, and it rinses clean when the job is done.
How this shows up on our jobs
We use professional bleach-stable non-ionic surfactants in every soft-wash mix. It's why you can see a clear line between the cleaned and uncleaned sections of a house during a job.
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Related terms
Surfactant
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 running off. In exterior cleaning, surfactants are blended with sodium hypochlorite and water to let the mix "stick" to vertical surfaces long enough for the bleach to kill organic growth at depth.
Soft 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 than scouring them off with brute force. A soft wash rig delivers cleaning fluid at roughly 60-200 PSI, comparable to a strong garden hose, which is safe on siding, shingles, painted surfaces, screens, and caulking. The chemistry does the work: the solution dwells on the surface, breaks down the organic growth at the cell level, and is then rinsed clean with fresh water.
Sodium 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 (commonly called "SH" or "pool shock"), roughly twice the strength of consumer bleach. When applied in a properly mixed soft-wash solution, it kills algae, mold, mildew, lichen, and bacteria at the cellular level within minutes and breaks down into salt water and oxygen.
Downstreaming
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 injector pulls detergent from a bucket through a siphon hose whenever a low-pressure (soap) nozzle is attached. When the technician swaps to a high-pressure nozzle, the injector automatically stops drawing chemical, allowing for a clean rinse without switching lines.
Dwell 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; it needs time to break chemical bonds, kill organisms, or dissolve minerals. Too little dwell and the chemistry is wasted. Too much dwell — especially in direct sun — and the chemistry can damage the surface, bleach landscaping, or drive the stain deeper.