Urea-Formaldehyde is commonly used as the adhesive to make ply wood for interior use. It is a non transparent, thermosetting polymer. Ply wood for exterior use is generally manufactured using Phenol-Formaldehyde resin, which is a more water resistant polymer. Phenol-Formaldehyde is not being discussed here.
I spent the day yesterday researching and trying to understand how Urea-Formaldehyde is produced.
The purpose of this post is to try to explain how I believe urea-formaldehyde is generally manufactured, in order to to establish what it is made from. I am craftsman, interested in the materials that I use. I am not a scientist. This means that I can only explain this subject on a simplistic level. It also means that I am interested to hear feedback from people with a greater scientific understanding of this subject. For example; Are there any sections of the manufacture process that I am misunderstanding?
If I’ve got this right though, It all starts with the fossil gas methane, and coal.
Urea-Formaldehyde resin is made with urea and formaldehyde. The reaction of these two compounds in such a way that they form resin that can become a stable polymer, involves 2 stages. Before this can happen though, the urea and the formaldehyde need to be produced.
Urea occurs in nature as the end product of protein metabolism by mammals, which excrete urea in urine. The manufacture of synthetic Urea begins with the mining and extraction of the fossil fuel Methane. Hydrogen is separated from the Methane through a process called ‘Steam Reforming’. This involves steam, high temperatures and high pressures and a nickle catalyst to separate the hydrogen from the carbon in the methane. A by product of this process is carbon dioxide, which is generally collected because it is required further down the line to make Urea. I wonder how effeciently the carbon dioxide is collected?
Having been extracted from the methane, the hydrogen is then combined with atmospheric nitrogen to make synthetic ammonia. This artificial nitrogen fixation process is called the Haber-Bosch process and once again uses a metal catalyst and high temperatures and pressures. Inteerstingly, Carl Bosch, one of the inventors of this process, was the nephew of Robert Bosch, who who pioneered the development of the spark plug and founded the multinational company Bosch.
The next step is called the Bosch–Meiser urea process and involves 2 stages. The first is carbamate formation: the fastreaction of liquid ammonia with gaseous carbon dioxide at high temperature and pressure to form ammonium carbamate. The second is urea conversion: the slower decomposition of ammonium carbamate into urea and water
Formaldehyde occurs naturaly throughout the universe. It is a simple chemical compound made of hydrogen, oxygen and carbon. All life forms – bacteria, plants, fish, animals and humans – naturally produce formaldehyde as part of cell metabolism. However for industrial purposes it is manufactured.
The creation of formaldehyde uses the Formox process which requires methanol and oxygen.
The methanol is made from hydrogen and carbon monoxide. The carbon monoxide is often obtained through the partial combustion of coal with air.
On an industrial scale, like in the manufacture of urea , the hydrogen required is predominantly produced from the natural gas methane by reforming the gas with steam, followed by the high pressure catalytic conversion of the synthesis gas to methanol. The result is a clear, liquid, organic chemical that is water soluble and readily biodegradable.
The liquid methanol is then subjected to the Formox Process; The catalytic oxidation of methanol at a temperature of 250-400oC. This produces the Formaldehyde required to combine with the Urea to make Urea-Formaldehyde Resin.
The actual reaction of urea and formaldehyde to form urea-formaldehyde resins gets pretty complicated. If I understand correctly it’s a 2 step process. Firstly, an alkaline methylation at a high formaldehyde to urea, consisting of the addition of up to 3 molecules of formaldehyde to one molecule of urea. This is then followed by an acidic condensation, meaning that water and an acid are formed as a by product.
The chemical composition of urea-formaldehyde (UF) polymer is [(O)CNHCH2NH]n in repeat units
Worldwide, about 20 million metric tons of UF are produced annually. Over 70% of this production is then put into use by the forest-products industry for bonding particleboard, MDF, plywood, and laminating adhesive.
It’s also used in agriculture as a slow release nitrogen fertilizer.
Valchromat is a moisture resistant MDF ( medium density fiberboard). It is unusual because the boards are coloured throughout, with organic dyes. This is important feature, because when it is cut or routed,the colour is still visible on all the exposed surfaces.
The colour choices are:
Who Makes it?
A company called Investwood designed Valchromat and manufacture it in Portugal. Whenever possible they use wood that is a by product from other production process’s. While they are still separate, the wood fibres are impregnated with organic colouring agents, which is why the boards are coloured throughout. After they have been dyed, the coloured wood fibres are chemically bound to one another using a special resin. This is a different method of production to the MDF that is commonly used in the building industry today, which uses a formaldehyde based adhesive to glue the fibres together.
Sound interesting to you? Have a look at the following video, posted by James Latham Timber. In it the presenter explains some of the properties and applications of Valchromat.
Valchromat as Biomass
According to the video above, at the end of the life of a Valchromat product, it can be recycled. Or it can be used as biomass. I find this fascinating, because most man made boards, produce toxic fumes when they are burnt. This means that, unlike untreated timber, they can’t safely be used as biomass without polluting the environment.
I wanted to know more about this and so I contacted Lathams timber.
I asked for more information about using Valchromat as biomass and they contacted Investwood for me. The response email read;
Please see the reply from Valchromat below.
We can confirm that the product is used as biomass for our hot air generator, we are self-sufficient with regard to biomass for the production of steam and hot air for the manufacturing process.
Well that’s a smart section of a production line! The waste is recirculated to provide some of the energy required to manufacture the product.
It’s excellent news to me as a carpenter working with the product, because the sawdust created when cutting it (which I collect using a dust extractor) is non toxic. I too can use it as biomass, and maybe even, I’ll be able to find a secondary use for this by product?
What can you build with it?
Valchromat can be used to build furniture, including chairs, tables and cabinates.
It serves a duel purpose when used as flooring, or wall panels because it has acoustic insulation properties. What’s more, it can be used for load bearing purposes, so it can be used to build staircases. I would love to build a multi coloured set of stairs!
It’s moisture resistant, therefore it can be used to make bathroom vanity units and kitchen cupboards. It is incredibly easy to make a door from Valchromat because it can be cut to size from 1 piece, only requiring a quick sand to finish the edges.
Also, because it is non toxic, it makes splendid toys for children.
In Conclusion, Valchromat is a colourful, non toxic building material with a wide range of uses and I would definitely recommend experimenting with it .
The term ‘ply wood refers’ to engineered boards of wood, that are manufactured by gluing multiple very thin sheets (veneers) of wood together. Each adjacent layer is rotated, often by 90 or 45 degrees, so the grain of the wood runs in different directions. This adds strength, reduces shrinkage and expansion, and greatly reduces the chance of the wood splitting when it is screwed through. The number of layers used depends on the final thickness of the board, and it is commonly available from suppliers in the UK in sizes ranging from 3.6 to 25 mm thick. A standard full size board is then 1220 wide by 2440 mm long. Smaller boards are available pre-cut and larger, thicker, and thinner boards can be bought, although generally take a bit more searching for.
The veneers of wood are cut from using a rotary lathe. This machine turns logs against a long very sharp blade that peels the wood in one continuous, or semi continuous roll. This technique of ‘peeling’ logs was invented by a guy called Immanuel Nobel in the mid 18 hundreds. One major positive factor for processing lumber in this way is how efficiently it uses up the wood from the tree, compared to milling it into planks.
All sorts of different types of wood are used to make ply. The choice people make depends on the requirements of the project the wood is to be used for, for example, if it’s for furniture, or a buildings structural construction, and whether its going to be used on the interior or exterior of a building. Sometimes the final outside layer of the wood will be an expensive, slow growing hardwood, such as walnut, cherry or oak. This is a very cost effective way to produce a fine finish for furniture or doors.
Once the veneers have been cut, they are dried and then glue is spread over the sheets. They are then layered and then pressed together while the glue dries. The types of glue used, once again vary, depending on the use of the plywood. Often for exterior used the glue is phenol-formaldehyde based and for interior use it is urea-formaldehyde based. One concern in using plywood is the potential off gassing of the glues chemicals long after production, and the possible health concerns that may arise because of this. Many manufacturers now use a low formaldehyde emitting glue, and some are experimenting with producing plywood using soy based glue. Large suppliers stock plywood that comes with an emissions rating, much like a paint’s Volatile Organic Chemical’s (VOC’s) rating. In my opinion this is something to be aware of.
In the plywood production process, once the sheets have been pressed and the glue has dried, the rough edges of the boards are cut away as they are trimmed to size, and then they are graded and packed, ready to be sent out to the wholesalers.
Plywood is produced all over the world from Finland to India and is classed as an environmentally sustainable building material. Certainly, if the manufacturers are using 100% traceable wood from responsibly managed forests, this section of the production is sustainable. As for the glues used, I will research further, and discuss in another blog post as this is extensive subject in itself and worthy of careful consideration.
There is no doubt that ply wood is a highly versatile building material with multiple uses, that simplifies many woodworking projects, compared to making the same thing from solid wood. If it is used correctly, that is; the right type for the job is selected, it is worked with care and finished suitably, it can be used to produce splendid items that should last for many, many years.
Here’s a short video I’ve made demonstrating cutting a dovetail joint using a router and and a trend dovetail jig. The joint is cut into 18mm plywood and has been used along with 3 other similar joints to connect the sides of a desks drawer.
I chose to use the company Super Skills who provide training and assessment in many areas of the constitution industry.
The assessor sent me a list of information that I would need to demonstrate a good knowledge about and number of 1st and 2nd fix carpentry tasks that I would need to complete. These included: hanging doors, installing door frames, architraves and skirting boards, putting in floor joists, laying floor boards and building stud walls.
On top of this I needed to provide photographic evidence of appropriate use of various power tools including: circular saw, router, planer, chop saw and drills.
When I had collected all of the evidence needed, the assessor came to meet me on site to meet me In the workplace and carried out a 3 hour interview. He went away with the portfolio I had prepared for him and then got back to me, to let me know I had provided him with everything he needed to award me with an NVQ2.
I recently took apart and rebuilt an traditional, old pine door. I have been told it was left for too long in a stripping vat and this caused the wood to shrink and crack and the joints to come loose leaving the door sagging on its hinges and dragging on the ground as it attempted to swing.
It was a fairly fiddley process that took about 12 hours. All the tenons had to be reconstructed, for which I used various pieces of hardwood. I also filled some of the major cracks with slivers of wood, and for the minor ones I made up a paste from, Lakeland Paint’s natural wood filler and their wood glue, also some fine sawdust and coloured acrylic paint to blend it in with the rest of the door.
Anyway, once it had been cleaned up, glued (also from Lakeland Paint) and clamped and left to set, it came out as a sturdy door with character, and hung again beautifully.