recycled timber

Hardwood and Softwood, what is the difference?

red elm end grain

Hardwood is not necessarily a harder material (more dense) and a softwood is not necessarily a softer material (less dense).

Different types of construction projects call for different kinds of timber, both hardwood and softwood are used for everything from structural to decorative.

Softwood and hardwood are distinguished botanically in terms of their reproduction, not by their end use or appearance. All trees reproduce by producing seeds, but the seed structure varies.

Softwood trees are known as a gymnosperm. They reproduce by forming cones which emit pollen to be spread by the wind to other trees. Pollinated trees form naked seeds which are dropped to the ground or borne on the wind so that new trees can grow elsewhere.

A hardwood is an angiosperm. Angiosperms usually form flowers to reproduce. Birds and insects attracted to the flowers carry the pollen to other trees and when fertilized the trees form fruits or nuts and seeds.

The hardwood/softwood terminology does make some sense. Evergreens do tend to be less dense than deciduous trees, and therefore easier to cut, while most hardwoods tend to be more dense, and therefore sturdier. In practical terms, this denseness also means that the wood will split if you pound a nail into it. Thus you need to drill screw or bolt holes to fasten hardwood together. But structural lumber is soft and light, accepts nails easily without splitting and thus is great for general construction.

To sum up

Hardwood tend to be darker, heavier, more expensive, last several decades, naturally resistant to weather.
Softwood tend to be lighter in color, lighter weight, cheaper, last for a decade or so and can be weather resistant but needs to be treated.

Reclaiming or not reclaiming

Indonesia is a treasure chest of biodiversity; it is home to between 10 and 15 per cent of all known species of plants, mammals and birds. Orang-utans, elephants, tigers, rhinoceroses, more than 1,500 species of birds and thousands of plant species are all a part of the country's natural legacy.

The mass destruction of Indonesia's rainforests and carbon-rich peat lands threatens this and is the main reason why Indonesia is one of the world's largest emitters of climate changing greenhouse gases.

The lives of millions of Indonesians who depend on the forests for food, shelter and livelihoods are also changing beyond recognition as the forest disappears.

This destruction also threatens our wider world; peatlands are perhaps the world's most critical carbon stores, and Indonesia's peatlands are vast, storing about 35 billion tones of carbon. When these peatlands are drained, burned and replaced by plantations, carbon dioxide is released and the conditions are set for devastating forest fires, which were responsible, for instance, for Singapore's "haze wave" in 2013.

In Kaltimber we aim to provide 100% reclaimed wood by knowing the origin of all our stock.

New owner

As per December 1st 2016 Kaltimber has a new husband-and-wife owner team!

After many years of hard work and constant improvement Yoga and Alex are going for new adventures while Guillaume and Siti are taking over!

On January 1st 2017, Kaltimber will resume its activities on decking, flooring, paneling, counter-top and other B2B oriented objects (in-house design or custom design).

  • Our production team; still is the same so you will continue to find this unique quality Kaltimber has to offer.
  • Our sourcing team; still is the same so you will continue to find quality reclaimed hardwood from ethical and legal sources.
  • Our sales team; still is the same so you will continue to find precise and professional information, quick reply and this forever smile.

We are looking forward to meet all of you to discuss and assist you on your projects, no matter how big or small they are.

Finish your wood with flair and care part 1.

Finishing wood in an appropriate way is exceedingly important if you want to get the best out of your wood. In this two-part series, we survey different types of wood finishes and look at what is right for you.

Before and after... teak chair finished with Woca oil

I have touched on this topic before, but really it deserves a book’s worth of attention. Little information is available to Indonesian consumers about wood finishes, and what is out there is by no means comprehensive, clear, or particularly accessible. For those of you with experience in this area, you may have noticed there are limited choices available on the local market. Your average local builder will tend to offer the standard polyurethane-based finished that they know, interchangeably called “plitur” or “Mowilex” (a brand-name). Sometimes a varnish traditionally made from resins called “sirlac” (Shellac) but nowadays made from pulmerised petro-based oils is used for finishing teak. Another product we can pick up in large Indonesian supermarkets is ‘fake’ teak oil, made from to petroleum distillates such as kerosene. The good stuff is usually made with a linseed oil base.

The sheer number of timber finishes available on today’s market can sometimes be a tad overwhelming! In Indonesia we are a way behind some of the European, Australian and American advances in timber finishes, however in recent years more options have become available. I will look at these products in the upcoming issues, but first, let’s look at some basics.

There are four different ways to treat or finish wood: oil, wax, varnish or pigment (paint or stain). The first three don’t add any colour to the wood, whereas pigment does. Let’s look at some pros and cons of the various types.

1. OIL

Permeates timber cells and simultaneously seals and protects. Oils are not affected by moisture content fluctuation of wood (they are elastic). Many wood oils are plant-based and hence environmentally sounder. Types include: Unblended Wood Oils (tung, linseed, soy, candlenut, castor), Polymerised Wood Oils (specially processed oils that have been heated to help them dry faster which create a harder surface film and a more durable glossy luster) and Pigment Oil-Based Stains (contain oil which enables the stain to penetrate the wood)

2. Wax

Fills all of the cavities in the wood to achieve an even finish that is polished. Wax doesn not achieve a film on the surface, as oils do. It creates a flat surface which allows you to polish the wood. Many oil finishes benefit from a light liquid wax coating , especially floors.

3. Varnish

Creates a transparent film coating over the entire wood surface. There are penetrating varnishes and non-penetrating varnishes. There are approximately 60-70 different types of varnish out there. In Indonesia there are probably around 10 different kinds, but many different brand names. Types include: Polyurethane Coatings (generally petro chemical-based which are thinned with petroleum distillates to enable easy application. They create a glossy finish and are easy to apply, however have potential health risks as, depending on the brand, they contain a high level of solvents/ chemicals. They can crack and darken over time, and provide a surface coating only, similar to a plastic film). Resin based varnishes made from tree sap.

4. Pigment

There are two kinds of pigment: paint, which puts a non-transparent film over the wood surface, and stain, which colours the wood but leaves the grain exposed. Pigmented Paint will protect wood indefinitely; however it will cover the wood so characteristics are not displayed. Also, some paints in Indonesia contain lead. Environmentally speaking, paints are one of the worst pollutants in the world. The best solution is using timbers appropriately, i.e exterior grade timbers outside, and softer interior grade timbers inside and accept that timbers grey with age as do we.

The type of coating that you use should be determined by timber type, use, desired gloss level or appearance, and your own personal preferences. Of these, there are more ‘natural’ choices and more ‘sythetic’ solutions.  Decide on final look first, and then move on to available options.

Stay tuned for the next issue, where I will review wood finishing products available on the Indonesian market. Till next time!

Designing for longevity: getting better life out of your wood

Naturally eroded end grain of a mahogany log... ain't she beautiful?

Two unavoidable factors that will impact upon wood in an exterior application are sun and rain. Why is it so important to consider these factors from the outset, and what can you do to minimise their impact?

We love the sun for generating solar energy, warming our bodies, growing trees and drying clothes. We love the rain for feeding food crops, watering plants and filling up dams for drinking. Both the sun and the rain are essential life giving forces on our planet. But when it comes to timber, the sun and the rain can be a powerful factor in shortening the potential lifespan of our timber structure.

Wood that is kept dry and away from sunlight in an indoor application will last indefinitely. But what happens when wood is exposed to the sun’s rays and moisture from the rain? In simple terms, the surface of the wood starts to break down and decay, and the wood begins to split, rot, warp, lose its rich colouring and literally fade to grey.

Decay and degradation in timber is caused by a variety of factors: attack from fungi and bacteria, attack from the sun’s UV rays and from moisture, and biological attack including termites and borers. We call these ‘biological hazards’. Timber is usually rated against its ability to withstand these biological hazards, and it is wise to explore timber durability and strength gradings before you start building to choose the best timber for the right application to maximise the life of your structure (see end section for references). One of if not the best timber to use in Indonesia for external applications is Ulin (Kalimantan ironwood -Eusideroxylon zwageri) as it is highly resistant and durable.

Solar degradation or weathering occurs when UV light from the sun causes chemical changes in the wood cells and breaks down the lignum and cellulose in timber making it brittle, whilst also dying out and shrinking the surface of timber in comparison to its inner section, causing the timber to split. The best way to protect against this is by simply ensuring that you use an exterior grade timber with an interlocking grain to reduce splitting, and a dense oily consistency to resist drying out. Another essential consideration is to build out solar attack by designing your structure so that east and west timber walls are shaded from setting sun and that all other timber elements are shaded from above. Adequate eaves can greatly increase the life span of your timber.

Rot occurs when timber is continuously exposed to excess water causing slow decay, with rot, mould and fungus slowly but forcibly degrading the timber. To protect against rot, make sure timber is kept free from direct ground contact. Use an exterior grade timber in exterior applications as per above. And make sure end timber is covered from above. Most water intrusion occurs at the ends of sections of timber or in joints where water can pond. The best builders paint inside their joints prior to assembly as well as designing joints so water can naturally drain from them.

A common building technique in Indonesia is to cut large, flat mortise joints into post and beam construction (see pic below). This is a big fat no-no in the wrong application such as a two story structure as besides weakening the timber, the joints are rarely snug-fitting hence water can gather in the mortises and causes decay.

Two story Ulin post and beam construction showing mortise join which weakens the wood structure - a big fat no-no

Two story Ulin post and beam construction showing mortise join which weakens the wood structure - a big fat no-no

It is much better to attach beams to posts using galvanized screws and bolts, using two per join on a diagonal (much stronger than one and better earthquake resistance - see pics above). Another builders trick, is to cut the corners off the ends of timber sections to reduce the direct end grain surface. This is why you often see posts chamfered around the top, or rafters cut off at an angle towards the end.

Showing beam bolted to post using screws, the correct way to attach beams

Showing beam bolted to post using screws, the correct way to attach beams

For both rot and weathering prevention, you can apply a finish such as a paint, oil or a stain. I won’t go into great detail here as timber finishing is a huge topic that will be covered in an upcoming edition. In brief, the best protection against weathering is really pigment as it effectively blocks the ultra violet rays from the sun. This is why when you remove the paint from a 100 year old timber house, the timber underneath looks new. However, it is not particularly practical for wood lovers as the downside is you can’t see the beautiful properties of the wood. Another option is a permeable finish such as wood oil. The benefits of using wood oil is that unlike a polyurethane finish, it penetrates into the wood cells and expands and contracts as the wood swells and shrinks in response to changes in the weather. The downside is it doesn’t provide lasting protection and you will need to re-apply the oil every year or so. We recommend a high-quality natural permeable oil-based sealer such as Tung oil which can be bought in Bali at Little Tree (

Remember it’s the combination of water and timber that cause most trouble, so design your house so the timber stays nice and dry and preferably out of the sun.

More info on timber durability and strength grading:

Thanks to Dave Hodgkin and Sam Shultz for input into this article.

Avoiding destruction in your construction

This 8km, 15 year old road in East Kalimantan is due to be shipped off to Bali and replaced with new illegal Ulin wood

This 8km, 15 year old road in East Kalimantan is due to be shipped off to Bali and replaced with new illegal Ulin wood

In today’s ever-globalising world, it is hard for the discerning consumer to know where the wood they buy comes from. How do we get reliable information the wood’s origins, particularly when production is increasingly less localised and further away from the point of sale?

It is not easy, but it is possible.

The current laws for both new and reclaimed wood are, quite frankly, not that great and wide open to loopholes, as a recent trip to Kalimantan showed me. Exploiting a 2008 regulation from the Ministry of Forestry on inter-island trading of Ulin (Kalimantan Ironwood), I met with traders who were busy setting up deals with communities to replace their 15 year-old Ulin roads and bridges with new Ulin, only to sell the old stuff to the Bali reclaimed wood market! The old wood was pulled up as the new stuff was being simultaneously laid down. As one trader said, ‘We can’t send it out of Kalimantan, but we can replace the old wood with new and send that out instead!’

Much of this imported reclaimed wood ends up in the yards of reclaimed wood wholesalers in Denpasar, who supply raw material to many projects and retailers on Bali.

What concerns me is the possibility that the demand for reclaimed wood in Bali and elsewhere is actually fueling greater destruction of the forests, instead of the reverse. We got into the reclaimed wood trade because we saw it as a way to re-use an old and valuable material, thus reducing demand on the need for new wood. The average punter we meet generally buys recycled timber in an effort to help the planet.

The government was obviously concerned to when in mid 2007 in an effort to ward off the extinction of Ulin, it froze all harvesting and trade of the species and instigated an island-wide inventory of remaining stands in natural forest. The moratorium on the harvesting and trade of Ulin lasted until mid-2008, when it was replaced by a new law that limited export of Ulin only to a handful of Kalimantan-based timber companies who had existing stocks of Ulin in their forest concessions.

Current regulations require that Ulin traders obtain an endorsement from the BRIK (Forest Industry Revitalisation Agency) and a permit (PROKALINDO) to export Ulin out of Kalimantan. Only a handful of companies currently hold this permit. This has made it very difficult for new Ulin traders to find export markets for their wood.

Reclaimed wood exports require all sorts of permit processes of their own, including site inspection by the forestry department, police and forestry permits and so on. But generally speaking, it is relatively simple for the trained eye to differentiate new wood from recycled.

The big issue is of course sustainability. It was unsustainable and rampant exploitation that led the government to implement a law to restrict Ulin trading in the first place. Ulin has a 50 year in ground rating, which means we can expect a heartwood post to last 50 years, or more if it above ground. Growing at around half a centimetre a year, a 5 x 20 board would be cut from a tree that is at least 40 years old. Roughly speaking, a sustainable cutting cycle for Ulin would need to be at least 50 years. We are all for wood being used by local communities for appropriate applications. But what will this community do when in another 15 years when the roads need replacing again and there is no wood left?

So here are the three things you need to make sure your wood is legitimate reclaimed wood:

  1. Ensure your supplier can provide evidence of the original structure the wood came from and its location (photographs or documentation)
  2. Ensure that the original structure was not replaced with new wood when it was demolished
  3. Only buy from trusted suppliers that can comprehensively and satisfactorily respond to your queries