| Surface | Finished SH mix | Notes |
|---|---|---|
| House | 1 to 3% SH | depending on how dirty the siding is; downstream injector pulling from a tank of bulk 12% SH delivers about 1.2% at the wand |
| Roof | 4 to 6% SH | roof algae is stubborn; the shingle manufacturers' own bulletin prescribes a milder roughly 3% bleach mix, the safe floor |
| Concrete | house-strength mix plus specialty chemistry | degreaser for oil spots, rust remover for battery-acid and fertilizer stains; label directions are the operating manual |
| Wood (fence SOP) | 50/50 cut of SH and water, adjusted to the condition of the wood | the strong end of the wood range, and where bleaching lives; weathered bare wood only |
| Wood, painted (preserving the coating) | downstreamed house-strength mix | same mix that cleans siding; deliverable is clean, not new |
A downstream injector (the $20 entry device) sips chemical into the water stream after the pump at roughly 10 to 1 water to chemical. Pulling from a tank of bulk 12% SH lands about a 1.2% mix at the wand: house-wash range. Dedicated soft-wash systems meter the ratio without re-batching between a house mix and a roof mix.
Bulk SH runs 10 to 12.5% from pool supply or chemical suppliers; laundry bleach is about 6% with additives.
| Surface | Dwell |
|---|---|
| House | 5 to 10 minutes (soap, watch the green gray out and lift, rinse before the surface dries) |
| Wood | demo runs 3 to 5 minutes; the SOP caps dwell at 10 minutes, and the cap is not advisory |
Dilution is plant protection: saturated soil and leaves shed dilute SH; dry roots drink whatever lands on them.
Pressure dialed down before the nozzle touches a board (dual-lance or adjustable wand): strong enough to clean, not to scar. Prove it on one board in a corner, every wood job, every time. Clean one board at a time, in one smooth pass, start off the board, end off the board. Never back and forth.
Dilution discipline: start weaker than you think you need, and only strengthen after you see the result. There is no undoing a mix that was too strong. Additives that earn shelf space: surfactant (clings to vertical siding through dwell) and neutralizer (post-roof).