Knowledge Base › Troubleshooting Atlas › H&E staining
Stain precipitate / deposit on sections
Also known as: haematoxylin scum, surface deposit
What it looks like
Fine dark granular deposit or a metallic sheen on the section surface, unrelated to tissue structures.
Where it usually appears: Unfiltered oxidised haematoxylin or a dirty stain bath.
Likely causes
- Surface oxidation scum on haematoxylin
- Unfiltered or old stain
- Debris in the stain bath
Immediate checks
- Filter the haematoxylin before use
- Skim surface scum
- Rinse the affected slide in acid alcohol and re-stain
Corrective action
- Filter/replace the stain and re-stain the slide
- Clean stain vessels
Preventive action
- Filter haematoxylin daily
- Keep lids on stain baths
- Change stains on schedule
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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