downstream injector vs soft wash

Downstreaming is not the same as a soft wash

A downstream injector sips chemical into a pressure washer. A soft wash puts a known mix on the surface and lets it dwell. The injector is a tool. It is not a method.

Downstream injectors are common because they are cheap and fast. The machine runs, a little hypochlorite is pulled in from a jug, and the operator keeps moving. The dose changes with the nozzle and the engine speed. Dwell is whatever time the operator happens to leave. On a mild film, it can look fine. On a real colony, or on a surface that cannot take pressure, it is how streaks and scars happen.

A soft wash, as we mean it, is a mixed solution applied at low pressure, left long enough to work, and rinsed. The pressure is for application and rinsing, not for scraping the wall. You should be able to see the difference: the wall changes color during the dwell, before the hard rinse.

There is nothing magic about the word. If you hire someone else, ask whether they are applying a measured mix and dwelling, or downstreaming while they walk. Both can be done carefully. Only one of them is what we are describing when we say soft wash.

The service this belongs to is House soft washing.