Pre-treatment & Cleaning Technician - Senior

Soak Cleaner Temperature And Concentration Window: How to Diagnose and Fix It Right | QLQ Guide

Why this keeps coming up

Soak Cleaner Temperature And Concentration Window is one of the recurring questions on finishing forums — and answers online usually jump to a single fix. There isn't one: the symptom has several causes, each confirmed differently, each fixed differently. This is the diagnostic sequence our lines run.

soak cleaner temperature and concentration window - Live line operation - QLQ workshop photo
Live line operation — QLQ workshop photo

Triage: symptom → confirm → first move

SymptomLikely rootConfirm byFirst move
Oily films after cleaningConcentration low or cold bathTitration + thermometerRebalance to card range
Etched or dullened partsConcentration too high / too hotWeight-loss checkDilute; verify card
Cleaning slow all dayBath exhausted by oil loadTitration trendDump on trend, add overflow
Fumes/boiling at tank edgeTemperature over specThermostat checkCut heat; verify control
Stains after dryingRinse drag-out from cleanerRinse conductivityCounter-flow rinse audit

The fix set with windows

  • Fix 1 — the card window — Alkaline soak typically 40–60 g/L at 55–70 °C for steel; card per alloy — brass and zinc run milder
  • Fix 2 — titration 2× per shift — Additions by titration, not by scoop; log every result
  • Fix 3 — temperature discipline — Thermostat + visible thermometer; 'feels hot' is not 60 °C
  • Fix 4 — oil management — Skim daily; overflow strips floating oil; oil load dictates dump timing
  • Fix 5 — time by soil — Heavy stamping oil needs soak time, not stronger chemistry; add agitation

Case method

A line fought adhesion failures 'randomly' for months. The cleaner ran 15 g/L under card and 8 °C cold — titration had drifted to weekly. Restoring the window and 2× per shift titration ended the failures within two weeks. (Method illustration: your own titration history will show the drift.)

On the floor: recognise, record, escalate

You seeYou doYou never do
Water beads after cleanerRun titration now, log itSend parts forward anyway
Bath smells/looks exhaustedReport trend for dump decisionDump the tank yourself
Parts look etchedNote concentration and tempNeutralize in rinse and continue
New part familyAsk for its cleaning cardCopy the last family's window

Engineer notes

  • One variable per corrective action; verify with the confirm-by column.
  • Records beat memory: log every trial on the tank card.
  • Two failed actions in a row is a senior call — escalate with your log.
Safety: Safety: hot caustic cleaners burn skin and eyes badly. Face shield and apron at addition, add chemicals to water, stir-in fully before loading parts.

FAQ

How do I know the cleaner is strong enough?
Titration — twice a shift, on the card. Color and smell lie; the titration doesn't.
Titration says fine but parts bead water — next?
Oil load saturation: skimming and overflow; the bath can read in-range and still be exhausted.
Dump decision — what rule do you run?
Titration trend: when additions stop holding range, dump; calendar dumping wastes chemistry.
What does a weak cleaner really cost?
Adhesion failures downstream — the cheapest stage on the line causes the most expensive claims.
Alkaline Zinc Adhesion Failure: How to Diagnose and Fix It Right | QLQ Guide