Seeing the wood for the bricks - Wood-fired kiln

Wood Focus magazine
,
17 Dec 2012

At HG Matthews, wood is being used to fire the portraits of 18th Century bricks. Eoin Redahan reports. 

Psychologists call it reduced plasticity. As we get older, our thought processes stiffen and we are less open to new ideas. But manufacturers cannot afford to slip into entrenched thought. If they don’t adapt to the changing economic climate, austere winds will blow them out of business. 

Jim Matthews and his colleagues at brickmakers HG Matthews in Buckinghamshire, UK, are among those seeking solace in specialist areas. ‘We were driven out of the lower end of the market, and [found it] increasingly difficult to compete in the middle end because of the cheapness of brick in those sectors.’ Having realised it was futile to compete with companies 100 times larger than his, Matthews veered towards top-end construction. 

However, the moment of woodfired epiphany only came about after a chance conversation with master craftsman Dr Gerard Lynch. ‘We’ve always been very keen on the idea of doing a wood-fired clamp just for fun. Dr Lynch was involved with the Colonial Williamsburg foundation in Virginia, USA, and invited one of their kiln burners over for a visit. He brought him over to visit our yard and showed us photographs of the clamps.’ 

With his curiosity suitably piqued, Matthews joined Lynch and his peers at Colonial Williamsburg in putting together a wood-fired clamp for a brick conservation open day. ‘When the bricks came out of the clamp, they were just so extraordinarily beautiful,’ he said. ‘They looked just like bricks from the 18th Century. We made the decision on the spot. We had to do this as a long-term product rather than as a one-off.’ 

Matthews realised that he needed plenty of help if his company was to make wood-fired bricks for a living. ‘The technique had died out in this country, and there was absolutely no tradition of that particular skill left in industry. So, we pretty much had to start from scratch with the invaluable help of Gerard [Lynch], and Jason Whitehead and Bill Neff from Colonial Williamsburg.’ 

To start with, the team at HG Matthews built a wood-firing kiln, which was smaller than a standard kiln to compensate for wood’s lower firing temperature. They secured a mixture of local hardwoods and trained their staff in a firing method that is quite different to firing with oil or gas. ‘An oil kiln takes about 22 hours to fire, whereas a wood kiln can take three or four days,’ Matthews noted. ‘It involves a lot of heavy manual work – cutting and splitting the wood, as well as stoking the kiln.’ 

While using coal, oil and gas drove down costs, an important facet of the craft almost vanished. ‘What was left behind was the extraordinarily attractive bricks that are produced only by firing with wood,’ he explained. ‘As the smoke rises through the kiln, you get glazing and other features on the surface. You get a very rustic effect, which is a perfect match for older builds. Builders of the past used [these] patterns in their bricklaying to create beautiful effects, [such as] using a glazed header within Flemish bond brickwork or diaper patterns.’ 

While the experts at Colonial Williamsburg passed on 75% of the necessary skills, Matthews and his colleagues had to smoke out the remaining 25% themselves, as the local clay they dig from the Chiltern Hills behaves differently when fired. ‘We’ve basically had to tune the process they taught us to our particular circumstance. One of the fantastic things about traditional British brickmaking is that the clay varies so much within the country. Traditionally, bricks were extremely idiosyncratic to their locality, because each type of clay behaved in a different way and came out in slightly different colours. This is a fantastic feature of old buildings that has largely been lost.’ 

Unsurprisingly, HG Matthews’ bricks are used in conservation work, from recladding old farmhouses to supplying bricks for the Royal Military Academy Sandhurst. ‘It’s only ever going to be a niche market, because it is an ultra-authentic product for the conservation sector,’ Matthews said. ‘The cost of production means the sales price is very high. We’re currently charging £1,750 per 1,000 bricks, while 1,000 cheap, machine-made bricks sell for about £250.’ 

Nevertheless, he noted that they have sold every single brick they have made to date. ‘We’re getting interest from specialist building companies producing top-end, oneoff newbuilds. These bricks give unmatchable grandeur to a building because it looks like they come from a bygone era.’ 

HG Matthews may have come a long way in a short stretch of time, but it is still demystifying the wood’s smoky wiles. ‘You get bewildering, chaotic effects,’ he added. ‘We’re slowly identifying what does what. Just like the early brickmakers and wood firers, we’re learning by serendipity as well as intelligent guesswork.’ 

Further information 
To watch a video of wood firing, visit www.hgmatthews.com  

Tough treatment for softwoods 
TRADA and BRE have begun a research project to assess the durability of softwood species from different regions in the UK. The study will involve laboratory tests to determine whether place of origin influences natural durability, and to see whether information can be used to predict the service life of incised timber. The study will also assess the effect incising and pressure treatment have on the performance of softwoods in ground contact applications. www.trada.co.uk 

Countering fire power 
The Loss Prevention Certification Board (LPCB) is revising two door standards to ensure door sets, shutters and smoke/fire barriers are fit for purpose. LPS 1197 now includes the inspection of fire doors and the maintenance of security doors and shutters, while both standards require that installations follow the LPCB Certificates of Conformity. Download a free pdf version of the standards at www.redbooklive.com