The high quality of our window joinery is no coincidence but the result of a well-thought-out and multi-stage quality control process. Sylwia Kowalkowska, Quality Control Specialist at Bertrand, walked us through the process in practice.
Although this time we’re focusing on wooden products, it’s worth noting that similar standards apply to the production of PVC and aluminum joinery. See how we ensure quality at every stage of production.
Quality control begins with raw materials
The quality control process starts the moment the raw material is received. When scantlings – specially prepared pieces of wood for further processing – arrive at the warehouse, we check their compliance with the order. We verify the wood species and dimensions. We also verify moisture content, which plays a key role in the future stability of the window frame.
The next stage involves cutting the scantlings to size. The operator checks the accuracy of the cut and dimensions. Then, the wood undergoes an initial machine sanding followed by processing on a milling machine. After machining, we inspect the wood structure for any previously hidden defects – such as cracks, knots, or internal discoloration.
Once verified, the components are glued into complete frames and sashes. There is no room for randomness here either – we check dimensions, angles, thickness, compliance with technical documentation, and the structural stability of the assembled elements.
Precision at every stage of production
The fitted elements are then machine-sanded in preparation for painting. This ensures the lacquer adheres evenly and durably. After that, the surface is finished with manual sanding for added precision.
The prepared frames go to an automatic paint line where protective and decorative coatings are applied. Once the lacquer has dried, we inspect the quality of the finish – checking for drips, surface uniformity, and aesthetic compliance. If necessary, corrections are made.
When the frames and sashes are finished, we install hardware, gaskets, and glazing units. At this stage, functional tests are carried out. We check that all components work properly, that the window opens and closes smoothly, and that the glazing is properly seated.
After assembly, we apply silicone to seal the structure. This is the moment for a final, comprehensive quality inspection – we assess the appearance, order compliance, and functionality. Any irregularities are immediately corrected.
Final quality control and assurance of the highest quality
The finished product is carefully packaged with special protection for components most susceptible to transport damage. This ensures the window or door reaches the customer in perfect condition – ready for installation.
Quality control in our company is not just an obligation. It’s a daily practice and a standard upheld by every employee. Everyone is responsible for their stage of production and approves only those products that meet the required criteria. Thanks to this, we can be confident that we deliver durable, aesthetic, and fully functional joinery to our clients.