Scope of this guide
Junior version: what you will see, what you record, and what you never touch. Recognise early, escalate fast.
This series answers a top recurring question from finishing forums with platingclub line practice. Parameters are industry-standard starting ranges — confirm against your supplier TDS.
Triage: symptom → confirm → first move
| Symptom | Likely root | Confirm by | First move |
|---|---|---|---|
| Milky haze, wipes off | Rinse contamination / bath oil | White wipe cloth test | Skim + check rinse overflow |
| Gray haze, will not wipe | Low bath temperature or CrO3 drift | Thermometer + Ba titration | Hold 50–60 °C; correct ratio 100:1 |
| Haze in recesses only | Throwing power limit | Position map of parts | Aux anode or reduce load width |
| Iridescent yellow-blue | Catalyst ratio off ( sulfate ) | Hull cell panel | Adjust sulfate 0.8–1.2% of CrO3 |
| Haze after nickel, not on nickel | Nickel passivated before chrome | Timing check transfer | Cut transfer time; re-activate |
Recognise, record, escalate
| You see | You do | You never do |
|---|---|---|
| Milky film | Report with photo, note tank temp | Add chromium acid yourself |
| Gray parts | Compare with first article of the shift | Re-plate immediately without report |
| Only recesses hazy | Record rack position on sketch | Load racks tighter to 'fix' it |
| Haze wipes off | Flag rinse tank overflow check | Wax or oil the part to hide it |
Engineer notes
- One variable per corrective action; verify by the confirm-by column.
- Records beat memory: log every trial on the tank card.
- Escalate when two consecutive actions fail — that is a senior call.
Safety: chromic acid mist is a carcinogen and burns skin. Mist suppressants, local exhaust and face shield are mandatory; report any chrome burn to first aid immediately.
FAQ
Why does my chrome look milky after rinsing?
Usually a contaminated rinse or an oil film — it wipes milky. Report it; do not add anything.
What temperature should the chrome tank hold?
Decorative chrome runs 45–50 °C. The log card shows the set point; report drift.
Can I re-plate a hazy part?
After stripping, yes — but the haze cause stays. Record the batch so the senior can trace it.