Monday, 29 October 2007


Some of the UK's forests were created hundreds of years ago as places for the rich to ride their horses...and now anybody can do it.

There are several jobs involved in working with horses in the forest and maintaining the bridalways. For small tree harvesting operations and tree thinning it is often best to use the traditional methods of horse logging. Horse loggers can move up to 10 tonnes of timber in a day leaving hardly a trace, and making hardly a sound. The big shire horses work best on flat lowland forests, while forests with hills and steep banks require smaller, more agile, horses. Horses are also used to move materials and equipment and to control invasive weeds like brambles and bracken.

Sunday, 28 October 2007

How trees are harvested

Think you know what a lumberjack is? A big guy with a beard, a checked shirt and an axe? Possibly saving girls in red hoods from wolves dressed as grandmothers? Well think again...

For starters the people (men and women) who take down the trees are called loggers or harvesters...and its all part of forest management, which also includes tree planting, silviculture, landscaping and a range of other 'forest operations'.

Technology has changed the job considerably from the days of yore. Chainsaws started to replace axes back in the 1920s, but these days most of the trees grown for timber in countries like the UK are felled by machines a bit like the ones you see on construction sites. These machines can cut a tree, strip the branches and cut the logs to length in a matter of they have a lot of other fancy gadgets GPS to locate the trees marked for felling. Other types of specialised machines are used to get the logs to the road and on to the sawmills.

All this is done while causing minimum damage to the forest floor and to young trees. The forest owners don't want their future timber crops to be put at risk...or any income they get from other uses of the forests such as recreation and tourism.

In some areas the land is so inaccessible that other methods have to be used, such as horses and helicopters ...or even submarines and machines that walk on legs!

Thursday, 25 October 2007

Reg Kehoe and his marimba queens

This one is a special educational content except the observation that marimbas are usually made of wood!

The bars for the lowest pitched notes are wider and longer, and gradually get thinner and shorter as the notes get higher.

Like the bars of a xylophone, the bars of a marimba are most commonly made from rosewood, but they can also be made from padouk and various synthetic materials.

Rosewood is the name given to a number of different timbers which have a rich dark red colour and a sweet smell. They are heavy and have strong resonance making them good for musical instruments. Unfortunately, many rosewoods, like Brazilian rosewood (Dalbergia nigra), are endangered due to over exploitation and should not be used.

The story of a forest ranger

This is another film from the excellent Prelinger Archive. This one was made in 1954 and looks at the job of the forest ranger in the USA. Again, you might recognise parts we used for our own videos.

Notice how the forests are talked about as a resource...but also how emphasis is placed on sustainable forestry and protection of the environment...even back in the 50s! Notice also how they stress the importance of avoiding forest fires. Back then many people smoked and lots of fires were started accidentally. Forest fires are still a big issue...all over the world (the UK included).

Monday, 22 October 2007

Wood for war - wood for peace

Ironically, the fact that we now have so many well managed forests in the UK is down, in part, to two of the most destructive events of the 20th Century: the two world wars.

During the First World War (1914 to 1918) Britain had great difficulty meeting the demands on timber - particularly for coal production and trench warfare. Britain's forests had been on the decline since medieval times and had been put under enormous pressure by the industrial revolution. Timber had been imported in large quantities for hundreds of years, but the war meant this supply was no longer reliable.

In 1919 the Forestry Commission was created and charged with reforesting the country with the help of private foresters. The idea was to improve the productivity of the forests and to create a large reserve of wood that could be called on in times of emergency.

Such a time came only a couple of decades later with the Second World War (1939-1945). During the war, the Commission's forests produced nearly one and a half million cubic meters of wood and nearly ten times more came from private estates.

These were times of great social change too. The 'lumberjills' were the forestry equivalent of the land army girls, but they weren't just felling trees - they were planting too...and the forests have been growing in size ever since.

Over the last 40 years or so the Forestry Commission has included conservation, ecology, recreation and tourism within it's objectives...and that's why we have today's multipurpose forests.

This is a video from the Prelinger Archive that was made during the Second World War looking at the same things from the American perspective. You might recognise parts we used in our videos.

Wednesday, 17 October 2007


Words cannot describe how much we love catapults. Some work because of the springiness of the wood (its elasticity) and some rely on its strength. The awesome trebuchet is in the second category.

Trebuchets work as huge levers. The short arm of the lever has a large counterweight on it and the longer arm has the projectile - which weighs a lot less. The potential energy of the counterweight is turned into kinetic energy of the small projectile. It's all in the physics - the bread and butter for engineers.

Warwick Castle has the world's largest. Check out their website with loads of historical facts and a flash game you can play.

If you're looking for a woodwork project why not try building your own mini trebuchet these kids did. The cola bottle is so cool! (8 minutes in)

Be safe though...not like the 'eccentric' guy in the third video!

Tuesday, 16 October 2007

Mountain biking

Have you watched our videos about Forestry Civil Engineering? Well this is one of the benefits of the work they do - mountain biking trails! Forests are very important to recreation, heath and tourism as well as being 'factories' for growing wood. If you live in Scotland check out 7stanes.

Monday, 15 October 2007

Wood and the environment

Today is "blog action day" so a good time to look at how the forest and timber industries impact on the environment.

Is using wood good or bad for the environment?

Well the answer is that it can be the moment.

OK, environmental issues are complicated so I'm afraid your going to have to concentrate while I try and explain this.

We all use wood products in our daily lives...and so it is very important that everyone understands this: there is good wood and there is bad wood.

Let's start with bad wood. Thankfully most people these days are aware that forests are being destroyed in some areas of the world. Some of this is because of logging for timber and some of it is because land is being cleared for other uses. This is a bad thing...for all sorts of reasons. As well as being the "lungs of the planet" forests provide homes to lots of animals and plants...and people too. Deforestation contributes to climate change and can also lead to landslides and floods. We hear a lot about the rain forests in South America, Africa and Asia, but forests are threatened in other areas as well...including Europe. Bad wood is wood that comes from:

  • Forests that are logged faster than they can regrow

  • Old growth forests, which contain important and rare habitats and which can't recover from logging

  • Forests that provide homes to endangered plants and animals

  • Logging that is linked to crime and poor treatment of native people

  • Logging that causes pollution or damage to the land

Buying bad wood is like buying a panda fur coat...and you wouldn't do that would you?

Now let's look at good wood. Wood is one of the few truly renewable materials we have. If we are careful about how we manage forests we can grow new wood to replace the wood we use. So long as forests are managed carefully they can provide wood forever. Indeed, thanks to responsible forestry for wood, the UK has more forests now than it had 100 years ago...and the forests are still growing.

Also, as trees grow they take carbon dioxide out of the air helping to combat climate change. When that wood is used to make products like furniture and houses the carbon is stored away and doesn't get back into the atmosphere until the wood product decays or is burnt...and that might be decades or even centuries. What's more is that we can make things out of wood that we would otherwise have to make from materials that cause environmental problems when they are made - like metals, concrete and plastics.

Forests can be factories for producing wood...and also provide lots of other good things too like homes for wildlife and nice places to go and exercise in.

So how can you know what's good wood and what's bad wood? Well, this is something that has been given a lot of thought in the last few years. There are now several "certification schemes" which aim to identify good wood. One of the best known is the Forest Stewardship Council (or FSC) which is supported by environmental organisations like Greenpeace, WWF and Friends of the Earth. You can find more information here and here. There is also an excellent virtual tour of a Finnish Forest explaining some of what is involved in sustainable forestry. And you can also learn a little more about the sustainability of different species by playing our timber trumps game.

Buying certified wood is a good encourages people to look after their forests. So look out for the certification marks.

Friday, 12 October 2007

Wood shrinkage

This is a delightfully retro video looking at the microstructure of pine wood and why it shrinks when it dries. It gets quite complicated with the terminology but has good visuals that help show how things work even if you don't understand the words. The things that look like air bubbles are meant to represent water droplets.

You might also want to look at our video about the chemistry of wood (on the firrs webpage).


Many people live in places where there is a risk of earthquakes. Timber is a good choice for houses in these areas because wooden construction is able to absorb a lot of movement and energy. Materials like brick and concrete are very stiff and crack easily so it is more complicated to make earthquake resistant buildings from them. Steel bolts and welds can also crack in situations like this.

In most cases the buildings won't actually be designed to survive a big earthquake without any damage at all. The most important thing is for the building to stay standing long enough so that people can get outside. People often choose to build their houses from timber because it makes them easy to repair after a natural disaster.

The first video shows a timber frame building and the second video shows a concrete frame building. Notice how this timber building is able to recover after large movements, whereas this concrete building can't.

Lolly stick bridges

We found loads of videos on the web of people's lolly stick bridge competions - from highschool science classes to engineering students at university...and in every single one people were having a lot of fun!

Now you could do this with lolly sticks (or popsicle sticks as the americans call them), modelling matches (the ones without heads), balsa wood, or with the wooden coffee stirrers you get in fancy coffee shops - you can buy a box of those quite cheaply. For fixings you could use glue, sticky tape, drawing pins, or even string.

Standing on the bridges looks a little bit risky - not least because everyone gets to know how much you weigh. Instead you could be more scientific and hang a bucket of weights off the bridge. The figures in this video are in pounds. There are 2.2 pounds in a kilogram.

There are lots of other things you can do instead of about cranes, towers, roofs or even fighting walls. You can even make a lolly stick bridge using no fixings at all - just lolly sticks and nothing else! Maybe one day we'll show you how...

Wood colour and chemistry

Here's a fun little video from the WoodWhisperer talking about how the colour of wood can change over time. This is all down to chemistry and something called oxidation. That's the same process that turns a sliced apple brown.

Sapwood is the outer part of the tree trunk - the wood that the tree is using to transport sap. The heartwood is the inner part of the tree trunk - the part of the wood that the tree uses to store waste chemicals...the extractives mentioned in this video.

As a tree ages the inner part of the sapwood slowly turns into heartwood. Heartwood provides structural support to the tree, but not much else and with very old trees it is common for the heartwood to be decayed away.

Different species of tree produce different extractive chemicals which explains why they can have such different colours.

Wednesday, 10 October 2007


Pykrete is a frozen mixture of water and wood fibre. Normal ice has very little tensile strength - it's brittle and cracks easily. The wood fibre helps spread the stress and bind together the ice making it many many times stronger.

It seems like a strange curiosity...but these days it is common to mix wood fibre with other materials like plastic and glue to make "composite materials" with improved properties.

Helicopter logging

There a several ways to get timber out of the forest, but perhaps the most spectacular method is by helicopter. This video shows a helicopter in action in Canada where the large distances and remoteness of the forests make this a viable option. It has been tried in the UK...the first time was in 1956 at Glenduror, near Fort William by the Forestry Commission.

Traditional timber frame 2

Here is a nice contrast to the "traditional timber frame 1" video. Again it's a class of students in the USA, but this time they are using modern machine tools for their carpentry. The most interesting bit is towards the end where you can briefly see some computer controlled robotic saws in action.

Timber frame DIY

It's possible to buy a timber frame kit house and to erect it yourself. Here is a video showing a photo montage of just that. The kit is made of small and light components that can be lifted into position without a crane. Timber frame is a very popular choice for people who build their own homes.

The green stuff is a special membrane that helps the building "breath" - a bit like a gore-tex jacket.

The stages of construction you can see here are:
1) The foundations (which would include all the drainage and other services)
2) Ground floor preparation (to get a nice surface and keep the water out)
3) The walls of the ground floor erected
4) The floor placed on the ground floor walls
5) The upper storey walls erected
6) The roof trusses erected
7) The windows installed
8) The outer brickwork laid
9) The roofing installed

Tuesday, 9 October 2007

Traditional timber frame 1

This video shows a group of students at a workshop in the USA building a traditional timber frame "post and beam" house using hand tools. Buildings like this are still being made (check out Carpenter Oak in the UK), but only for special projects. They require skilled craftspeople and large pieces of timber so are not practical for everyday houses... but can be very beautiful.

In contrast, a modern timber framed house is usually made from pieces about twenty times smaller in size! ....but that doesn't necessarily mean that a modern house won't last as long. The timber is used in a different way that allows for the forces to be carried by a larger number of smaller pieces. The wood is almost always a softwood like spruce, pine or fir which is dried in a kiln before it's used for building.

In this video it looks like the wood is a softwood, but post and beam houses are also often made from hardwoods like oak. In both cases, the timbers tend to be too big to be dried before use, so the connections must all be made to allow for the timber to shrink as it dries out as the building ages.

Check out "Traditional timber frame 2" to see the same sort of thing, but with modern power tools.

Japanese fighting walls

OK...we admit we don't know an awful lot about what is going on here because these videos are in Japanese.

What we think is happening is that people (engineering students?) are competing to create the strongest timber wall made with traditional carpentry joints. The walls are made to "fight" each other in pairs by putting a hydraulic jack between them that pulls them together (like tug of war in reverse).

The first video shows the construction of the walls and the second video shows the walls in action (perhaps the best video of the three). The third video shows the final stages of the competition.

The forces must be huge to cause these walls to break ...but you could stage your own miniature competition by making walls out of wooden lolly sticks or coffee stirrers.

Timber kit timelapse

This video shows a short timelapse of a timber frame house being looks like this was a demonstration during an exhibition. Many houses are now built like this in the UK. The timber kits are made as wall and floor panels in a factory and transported to the building site on a lorry in the right order for them to be placed on the foundations. A normal sized house can be put together like this in a matter of hours ...but this speed doesn't mean poor workmanship. In fact factory prefabrication (or so called "modern methods of construction") allow much tigher quality control than is possible outdoors on a busy building site.

Normally the house is then clad with brickwork to keep the wind and rain out...protecting the timber as well as the people living in the house. As far as most people can tell, the finished house looks like it is made from bricks.

The video seems to freeze 3 seconds in so you may need to drag the playhead to get it started again.

Friday, 5 October 2007

The walking harvester

A Finnish company owned by John Deere has developed a tree harvesting machine that walks through the forest like something out of a science fiction film. Even the wheeled and tracked harvesting machines are like a cross between a space ship and a sports 4x4.

The machine is useful in areas with difficult terrain ...where land has been turned to forestry because it can't be used for much else. Notice how lightly it treads...allowing forests to be managed for timber with the minimum of environmental impact.

The video shows the harvester in slow motion - it would be interesting to see how quickly it can really move!

Tuesday, 2 October 2007

Launch of the firrs DVD

In October we will be launching the "firrs DVD" - over two hours worth of videos about the science and technology of wood and the people involved a whole load more cool stuff.

If you live in Scotland you qualify for a free copy, which we can post to you if you let us know where you live.

We will be launching the new DVD at the Forest Education Initiative and Forest Schools Networking Event in Pitlochry on the 4th and 5th of October.