To qualify for the NTR Control, the certification system for treated wood which entitles products to carry the NTR mark, companies must implement a functioning internal quality control system. The purpose of these internal quality controls is to be able to control treatment processes in such a way that they will produce the required product quality.
In addition to the special requirements and demands of the NTR-documents, there are other conditions the internal quality controls have to meet, such as those required for certification according to ISO 9002 and the SFS 1998:901 directive on companies’ own internal controls. Larger companies in EU must meet the requirements in Industrial Emission Directives and the related BAT conclusions.
The most important points that need to be covered by internal quality controls are:
- Inspection of the wood before treatment
- Inspection of the treatment solution before treatment
- Selection of the appropriate treatment process as well as documentation of the entire course of the process
- Checking the results (penetration and retention of the treatment solution) after the treatment process
- Labelling of the treated wood
- Checking correct fixation and the storage of treated wood
- Treatment protocols
These requirements is described NTR- documents and in the publication Factory Production Control.
To enable the internal quality controls to be carried out in the best possible way, it is imperative that the operating staff and the supervisors are properly trained and that they show their interest and commitment to production and quality issues and that they are authorised to remedy any shortcomings or defects should they arise.
Further reading and education
Advice and Guidelines for the internal quality control of vacuum pressure treatment plants is a comprehensive document that introduce best practice to a treatment plant and it staff.
These guidelines are directed primarily at wood treatment foremen and works managers at treatment plants using water-soluble wood preservatives in compliance with NTR norms. It is to be hoped that these guidelines will find widespread use and acceptance and contribute to the improvement and efficiency of treatment companies’ internal controls as well as to the production of even better and more consistent quality in treated wood.
As these guidelines are to be further optimised in future, any proposals for improvements will be gratefully accepted.