Technically Speaking - Page 1Stay up to date with the latest technically speaking features from the global wood based panel industry
Latest Technically Speaking Update
Pre-Pressing Pre-pressing compresses the raw mattress of a panel before it enters the main hot press. Dr Mark Irle explains the benefits
Density The market demands low density panels – but density affects mechanical strength. Manufacturers must therefore keep tight control over their process lines. Dr Mark Irle gives guidance.
Panels for health Articles in the general press on wood based panels (WBP) often tend to be rather negative and present our products in a poor light. Commentaries on things like formaldehyde and VOC emissions, dust and noise from factories inevitably put the industry into a defensive stance. One reason for this is the links these issues have with social wellbeing.
The fibre market could be warming up I am writing this article in early January; a time that is normally quite cold, but is, at the time of writing, rather mild in France and across western Europe as a whole. Even so, I am glad to be inside a well-heated and insulated building.
New ways to recycle The wood recycling sector is still relatively young so its collection and processing are still maturing.
Size matters Commercial hot presses are very large compared with typical laboratory-scale ones. It would be nice to have a big press in the laboratory, but then I would need a big forming station, a larger blender and so on.
All of us, at one time or another, have probably counted the number of growth rings in a tree in order to determine its age.
Ring width is associated with the growing conditions, which can...
A new use for old MDF MDF has been manufactured commercially since the 1970s and is a great commercial success.
A question of fibre My research is generally applied research and closely linked to industrial problems. Sometimes, however, fundamental data is required. I am currently involved in a project called ECOMATFIB. The aim of the project is to develop novel fibre-based products.
In the zone The manufacture of plywood requires large sheets of veneer. A typical panel is 2.44 x 1.22m (8 x 4ft), with the face veneer grain direction parallel to the longest edge of the panel. Such a structure requires veneers that are cut from logs, or more correctly bolts, that are more than 2.44m long for the faces and 1.22m long for the inner cross veneers.
The story of knots The appearance of knots in sawn wood and veneer is caused by grain deviation to accommodate the wood found inside the branches of trees.
Stop-per & think! Cork is a fascinating material with quite amazing properties. We are all familiar with its uses as stoppers for wine bottles, flotation devices and insulating materials, but not many know where it comes from and why it has these superb characteristics.
VOCs explained In the last issue I defined VOCs (volatile organic compounds) and in this issue I shall give an overview of the VOCs that are emitted from wood products. As I am sure readers will know, wood consists almost entirely of organic components and this fact is behind the excellent environmental credentials of wood products. The volatile components are almost exclusively derived from the extractives.
Surface tension Persevere with this article on how adhesive properties affect glue/wood bonds: the reason for the definitions at the start will become clear by the end (I hope!).
Heating matters I think I am right in saying that the manufacture of wood based panels, except those bonded with cement or other inorganic compounds, always involves a hot pressing step. The hot press is needed to transfer heat to the panel so that the adhesive can polymerise rapidly.
Talking about the weather..... The weather has been a much discussed topic in Europe as the cool, wet spring continues to cause problems for farmers and travellers alike.
It’s all about energy Nearly everyone knows that wood shrinks and swells, but very few understand why it does so. If I place a dry piece of wood in a sealed chamber that also contains a beaker of water, the moisture content of the wood will increase and it will swell. Do you know why the water molecules travel from the beaker to the wood? If not, then read on.
pH and why you need to know it As many of you will know, the vast majority of wood based panels are made using formaldehyde-based resins. The curing rates of such resins are very dependent on the pH of the environment in which they cure and so the pH of the wood species used can have an effect on adhesive cure.
In a recent practical class on adhesive bond quality, my students remarked on the waviness of the poplar and beech veneers being used. The distortions are due to differential shrinkage during...