How Wood Veneers Are Made
The beautiful veneers in your home undertake quite a long journey from the moment they are felled as a tree log in the forest. A lot of hard work goes into producing these beautiful pieces of wood and here we go into more detail about how wood veneers are made, helping you to appreciate them even more.
Step 1: Classification
After the tree log has been felled in the forest and packed onto the lorry, it is then sent to the log yard where it can be classified by species and stored in optimal conditions. To keep the timber in good condition it needs to be exposed to the right level of humidity by spraying water or by soaking it in water ponds. This will help to stop the log from degrading, which often happens when it is not given enough moisture.
Step 2: Debarking
The next step is to debark the log. Specially designed machines come into play here to carefully strip all the bark off the wood, taking care not to damage the core, which is where the veneer will eventually come from.
Step 3: Softening
With the log now stripped, its moisture content now needs be raised. This will soften the fibre of the wood which makes it easier for the next stage of the process. Steamers with a temperature ranging between 80°C to 100°C are used to place the logs into and it can take anywhere from 18 to 72 hours to complete. Because the log can quickly dry out again, it must be cut within one hour of this process to maintain its quality.
Step 4: Log cutting
The slicing method being used to produce the veneer will dictate how and where a tree log is cut. Each log already has its own identification marker, which makes it easy to see the various cuts that are being used. The log will also need to be peeled, so in preparation for that stage it will be cut in half or into quarter pieces.
Step 5: Peeling
Here, the tree logs are sliced into veneer sheets, which can be done in a variety of different ways. The most common is a flat slice, with the cut occurring parallel to a line through the middle of the log, producing a neat, uniform sheet. The rotary cut is another method used, with the cut following the annual growth rings of the log, which produces a wide sheet. Quarter slicing ensures the blade cuts into the growth rings at the right angle to create a series of straight lines. You also have the rift slice, which produces a comb affect, or a half round slice, which is a cross between a flat slice and a rift cut.
Step 6: Drying out
The natural order of the log is maintained after the veneer sheets have been cut and before they are carefully entered into the dryer. It only takes a few minutes for each sheet to be dried as they are exposed to extremely high temperatures of up to 320°F, with the heat blasted onto the surface of the material. However, the veneer won’t be completely dry as this process ensures that around 10% of the moisture content is maintained.
Step 7: Quality checks
To verify that the logs have been cut, peeled and dried to the required standard, quality checks are carried out after they have left the dryer. Each sheet is reassembled to form the structure of the original tree log before undergoing several identification checks. The wood veneer is closely examined and classified by an expert whose job it is to ensure that the veneers being sent out to customers are of a high enough standard.
Step 8: Clipping
Next, a clipper is used to create sheets of even length before the process is repeated to ensure they are also of the correct width. This is a vitally important stage as the precision and angle of the cut will heavily influence the final quality of the veneer panel. Once completed, the panels can then be transferred to the glue machine which is used to bond the veneer sheet edges.
Step 9: Splicing
This is where the matching process takes place, so the final product has the right level of consistency throughout. There are several matching methods that can be used, including booking matching, slip matching, running matching, balance matching, reverse slip matching, end matching and many more.
Step 10: Packing
The final stage of the process involves the packaging of the sliced veneers so they can be transported onto the next stage of the supply chain. This involves measuring and labelling the stock so there is a clear indication of the width, length and other key information. They are then loaded onto pallets and wrapped with protective polyethylene, before being loaded onto lorries and sent to their next destination.
How thick are veneers cut?
The thickness of the cut depends on the mill producing the veneer, but for general commercial purposes they are sliced into sheets that are 1.5mm thick, down to 0.4mm. At the thinner end of the scale these types of veneers are used for manufacturing economy products, while the thicker veneers are used for higher end objects.
A thickness of around 0.6mm tends to offer good strength and reliability, particularly for home projects. For constructional uses, 1.5mm to 2.5mm is the recommended thickness to look for.
What are veneers glued to?
All veneers must be glued to a flat, smooth, stable substrate that will not expand or contract when exposed to changes in temperature or moisture levels. The most common type of veneers used include:
This is a cost-effective option that is smooth, flat and very reliable and easily accepts a veneer being glued onto it.
While not as reliable as MDF, it is still a good choice. Baltic birch plywood may be a better option than heavier MDF for large doors, although warping can be an issue with this type of wood.
Another good option is particle board, although you will need to sand down boards that have a melamine surface to allow the glue to properly bond.