Name the soil before judging the result
Machinery described as grease-covered is rarely carrying one substance. Write down what is actually on the housing: fresh oil film; oil that has thickened and darkened in corners and around fasteners; dust and abrasive fines bound into that film; coolant or cutting-fluid residue; resinous or waxy build-up; rust-looking staining that may be a deposit rather than the metal. Each class behaves differently under heat, dwell and vapour, and a single pass verdict hides that. The trial record should carry one line per class, so a clean patch on the oil film is not counted as a win on the bound residue beside it.
Judge adhesion, coverage, heat and dwell separately
Operators who blame technique for every failure lose the useful signal. Separate four causes and record which one applies to each patch. Adhesion: the deposit is bonded, not merely sitting on top, and loosening is the real job. Coverage: the nozzle reached the surface, or the geometry blocked it. Heat: the vapour arrived with enough energy at the surface, which drops as the mass being cleaned grows cold and thick. Dwell: whether the vapour was held long enough for the film to respond. A patch that failed for dwell can be fixed on the next pass; a patch that failed for adhesion usually changes the plan.
Protect bearings, ways, drives, panels and openings first
Before any second pass, list what must not be wet and what must not be heated: shaft ends, bearing points, guideways and their covers, belt and drive areas, encoder and sensor heads, cable entries, junction boxes, nameplates, and any opening that drains somewhere you cannot see. Note how each was shielded, and whether the shielding survived the pass. Heat-sensitive items are reviewed twice, because a surface that looks unharmed can have lost grease from a bearing or lifted a label. Anything that had to be masked, bagged or blocked is itself a finding: the more of it, the more the method costs in preparation.
Trace every drop of run-off and condensed water
Steam looks tidy and is not dry. After each patch, follow where the water went: off the housing into the base, along a seam into an interior, into the drain or nowhere at all. Check under the machine, behind panels, in cable troughs and in any recess that holds liquid. Condensation on cold surfaces above the work is easy to forget until it drips onto something finished. A pass that leaves clean housings and a wet base is a failed pass, and this is the single review item operators most often skip because the machine looks finished.
Review residues, film and re-lubrication, not just cleanliness
Removing soil is half the job. Inspect what remains: smeared film on a vertical face, residue pushed into a seam and left there, streaks that will show the next time the surface is inspected, and dulling or discolouration on painted or plated areas. Then check what the heat removed that should have stayed — a lubricated point that now reads dry, a seal that sweats after warming. Record whether surfaces had to be dried, re-oiled or re-greased after cleaning, and how long the machine stood before it was safe to run again. A method that trades cleanliness for a dry bearing has simply moved the cost.
Score the trial by water, labour, utility and training load
Record what the pass actually demanded. Water use and disposal, since run-off carrying oil and fines has to be handled somewhere. Labour around the pass: shielding, waiting, wiping, drying, and the cleanup after. What had to be available — a power point in reach, a water feed, a place to stand, clearance around the machine. Then the human side: how long a new operator needed before the pass looked the same as the first one, and whether the outcome held when someone else held the nozzle. A method that works in careful hands and fails in rushed ones is not yet a routine. That is the point at which teams weigh industrial steam cleaning equipment against the methods already on site.
Decide per surface family, and know when to stop
Do not let one verdict stand for the whole machine. Split the outcome by family: open painted housings, horizontal decks, seams and joints, cast and machined surfaces, guards and covers, electrical and instrument areas. A method accepted on the first three and refused on the last two is a normal, useful answer. Set the stop conditions in the same record: the same class of deposit surviving a second pass; run-off reaching an opening that cannot be sealed; a sensor, seal or label affected; a prep time that exceeds the cleaning time. If two of those appear, stop and change the plan rather than adding another pass.
The handover that makes a trial worth running is a short written standard: which machinery families are handled this way, which deposits it clears, which deposits it does not clear, what must be shielded, how run-off is routed, what is checked before the machine runs again, and which findings end the pass. For plant where oil and cutting fluid are the standing problem, that document is also the honest way to describe factory machinery degreasing to the people who will run it, and the right moment to ask for customized steam cleaning equipment sized to the machinery you actually have. Review the trial this way once, and the next cleaning plan arrives with evidence instead of impressions.
