Scope of this guide
Intermediate version: symptom-to-cause triage with the confirm-by column — find the variable, run one change, verify.
Series: finishing.com recurring questions answered 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 |
|---|---|---|---|
| Peels in sheets, bare steel shows | Surface contamination pre-plate | Water-break + peel map | Pre-clean audit before dosing |
| Blisters after bake | Hydrogen entry + baking missed | Bake log vs spec | Enforce bake window per spec |
| Adhesion fails on high carbon steel | Substrate-specific prep needed | By-alloy pattern | Stronger activate for that alloy |
| Peel at edges after storage | Post-dip/rinse contamination | Storage test samples | Rinse quality check |
| Random scattered failures | Cleaner bath exhausted | Cleaner titration log | Rebalance or dump per trend |
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: alkaline zinc baths are caustic and hydrogen from pickled steel can ignite. Caustic-rated PPE, no flames near freshly pickled loads, eyewash at the line.
FAQ
Water-break test — where exactly?
After the last cleaner stage, before acid: beads mean oil remains; sheeting means clean.
Which fails first: cleaner or activate?
Usually cleaner: exhausted cleaner hands oil to the activate, which cannot fix it.
Why do high-carbon steels peel more?
Surface chemistry differs; they need their own prep card and activation strength.