Yellowing complaints arrived from three customers in one quarter, yet every shipment passed the color check at packing. The domes darkened weeks after shipment, not at the gate.
This management case guide closes the loop: a cure log that proves full cure, an aging test that predicts yellowing, and supplier gates that stop weak resin batches at the door.
Common Mistakes and How to Avoid Them
| Mistake | Why It Happens | Practical Fix |
|---|---|---|
| 1. Packing check only | Yellowing appears later | Add aging test to release |
| 2. Cure guessed | Under-cure yellows fast | Log time and temperature |
| 3. Oven variance | Same setting, different cure | Verify part temperature per batch |
| 4. Resin batch changed | UV stability shifts | Gate every resin batch |
| 5. No retention samples | Complaints unprovable | Keep samples per batch |
| 6. Rejects treated one-off | Pattern missed | Review complaint log monthly |
| 7. Hardener stock old | Color drift over time | Rotate stock by date |
| 8. Supplier data trusted | Certificate differs from batch | Test incoming batches |
| 9. No feedback loop | Same complaint repeats | Close the loop with data |
Best Practices
- Log cure time and temperature for every batch
- Run a 7-day aging test before release
- Gate incoming resin with UV stability checks
- Keep retention samples per batch for six months
- Review the complaint log monthly
- Close each complaint with batch data
Implementation Roadmap
| Step | Frequency |
|---|---|
| Cure log | Per batch, per oven |
| Aging test | 7-day sample per batch |
| Supplier gate | UV stability per delivery |
| Retention | Sample per batch, six months |
| Complaint review | Monthly pattern check |
Yellowing control flow
- Cure - Log time and part temperature. (Unlogged cure drifts batch to batch.)
- Age - 7-day 60°C sample test. (Packing checks miss late yellowing.)
- Gate - UV stability per resin batch. (Supplier certificates can differ.)
- Close - Complaint to batch data. (One-off fixes hide the pattern.)
Yellowing is a cure and material story, not a packing story. | Retention samples turn disputes into data.
Yellowing control data
Reference values for dome yellowing management.
| Parameter | Reference | Why It Matters |
|---|---|---|
| Cure temperature | 60-80°C per resin spec | Under-cure accelerates yellowing |
| Cure time | Per cure curve, logged | Shorter cure means weaker aging |
| Part temperature | Verified inside the oven | Oven setpoint differs from parts |
| Aging test | 7 days at 60°C | Predicts months of field life |
| UV stability | Per resin batch gate | Supplier batches differ |
| Retention | 6 months per batch | Proves or closes complaints |
| Hardener rotation | First in, first out | Old stock drifts color |
Yellowing complaint log
| Quarter | Complaints | Common factor | Action |
|---|---|---|---|
| Q1 | 3 | Shortened cure shift | Cure log added |
| Q2 | 1 | Old hardener stock | Stock rotation |
| Q3 | 0 | None | Supplier gate |
Release gate card
| Gate | Check | Pass criteria |
|---|---|---|
| Cure log | Time and temperature | Matches spec |
| Aging test | 7 days at 60°C | No yellow shift |
| Supplier batch | UV stability | Certificate matches |
| Retention | Sample stored | Six months |
Case 1 - three complaints closed by a cure log
Scenario. Three customers reported yellowing 3-8 weeks after delivery while packing checks passed; a shift had shortened the cure cycle to recover time.
Action. A per-batch cure log with part temperature was started, the shortened cycle was reversed, and a 7-day aging test was added to release.
Result. Yellowing complaints stopped within two quarters, and the cure log proved every disputed shipment.
Case 2 - a supplier batch that failed the plant gate
Scenario. A resin delivery from a new lot passed the supplier certificate but yellowed in the plant's own aging test after domes were already dripped.
Action. The supplier gate moved to the plant's 7-day test, the failed lot was quarantined, and retention samples were kept for six months.
Result. No yellowing reached customers, and the gate now catches weak lots before production.
Frequently Asked Questions
Why do domes yellow after shipping?
Under-cure or low UV stability in the resin batch; both age into yellow.
Why does the packing check miss it?
Yellowing develops over weeks; the check sees only the day of packing.
What cure log is needed?
Time and actual part temperature per batch, not just the oven setpoint.
How to predict yellowing?
A 7-day aging test at 60°C approximates months of field exposure.
Why gate the supplier?
Resin batches vary in UV stability even with the same certificate.
How long keep retention samples?
Six months covers the complaint window and matches customer claims.
Does hardener age matter?
Yes - old hardener drifts color behavior; rotate stock first-in first-out.
How to close a complaint?
Pull the cure log, retention sample and aging test for the exact batch.
What is the yellowing target?
Under 1 percent rework and zero confirmed yellowing complaints per quarter.
What Would You Like to Solve?
Tell us your cure schedule, resin batches and complaint pattern, and a cure log plus aging test usually closes yellowing cases within a quarter.