---
title: Blue stain on veneer
description: “Blue stain” spots on the veneer sheets are a reaction of tannic acid from the wood and the iron in the steel of the knife and/or the pressure bar.
image: https://www.tkmgroup.com/hubfs/Blue%20stain%20on%20veneer-1.png
---

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Plywood Industry

# Blue stain on veneer

![](https://www.tkmgroup.com/hubfs/Blue%20stain%20on%20veneer-1.png)

 14.12.2020 [ TKM ](https://www.tkmgroup.com/en/troubleshooting/author/tkm)

## Blue stain on veneer

"Blue stain” spots on the veneer sheets are a reaction of tannic acid from the wood and the iron in the steel of the knife and/or the pressure bar.

This phenomenon can be found in wood species with high tannic acid content such as red or white oak, cherry and walnut.

To avoid blue stain spots on the veneer sheets:

- Use [TKM NOVACROM](https://www.tkmgroup.com/en/machine-knives-and-saws-for-the-wood-industry) quality for knives
- Use TKM stainless steel for pressure bars
- Always keeping the cutting tools as clean as possible

### Relevant articles

- [
  
  
  
  ##### Clipper knives
  
  
  
  ](https://www.tkmgroup.com/en/troubleshooting/clipper-knives)
- [
  
  
  
  ##### Varying Thickness of Veneer
  
  
  
  ](https://www.tkmgroup.com/en/troubleshooting/varying-thickness-of-veneer)
- [
  
  
  
  ##### Rough Veneer Surface
  
  
  
  ](https://www.tkmgroup.com/en/troubleshooting/rough-veneer-surface)

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| --- | --- |

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