Knowledge Base › Troubleshooting Atlas › H&E staining
Bluing step fails (nuclei stay reddish-brown)
What it looks like
Nuclei appear reddish-brown instead of the expected blue after the bluing step.
Where it usually appears: Typically observed after the hematoxylin and eosin staining process.
Likely causes
- Insufficient bluing time
- Incorrect pH of the bluing solution
- Inadequate rinsing after hematoxylin
- Old or ineffective bluing reagent
- Over-decolorization of hematoxylin
Immediate checks
- Verify the pH of the bluing solution
- Check the timing of the bluing step
- Inspect the rinsing technique after hematoxylin
Corrective action
- Extend the bluing time if too short
- Adjust the pH of the bluing solution as needed
- Rinse slides thoroughly after hematoxylin
Preventive action
- Regularly check and calibrate pH of bluing solution
- Use fresh bluing reagent
- Train staff on proper rinsing techniques
This atlas is for educational purposes for laboratory professionals. It does not replace your institutional SOPs, manufacturer instructions, validated protocols or pathologist judgment. Adapt any action to your laboratory and equipment.
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