Q&A: Our Steam Bending Technique
You asked...we listened.
Here at Tom Raffield we receive so many great questions regarding our pioneering steam bending technique that we thought it was about time that we answered them for you.
Q: How long have you been steam bending wood for?
TR: My fascination with steam bending wood began whilst studying at Falmouth College of Art and I continued to explore the process whilst studying 3D Design at Falmouth University. So, I guess about 16 years or so.
"The vision for many of my designs came from my primary interest in structural materials, wood and its changeable states. Years of research and experimentation allowed me to develop a new steaming method to make my designs."- Tom Raffield, Founder.
Q: What else can steam bent wood be used for?
TR: Steam bending is an ancient process that's been used across a number of industries for centuries. The steam bending process is most commonly used for making instruments such as violins and guitars, walking canes, bending the hull of boats and of course, furniture making.
Q: What kind of steamer do you use?
TR: When I first started steam bending wood and reading up on the topic I was struck by how long the lengths of wood needed to be for traditional steamers. The designs I wanted to create were much smaller, so I tried to reinterpret the steam bending technique to make it more applicable for my lighting and furniture ideas. I developed a steam-filled bag technique that would allow me to work on smaller sections of wood.
Q: How long do you leave each piece of wood clamped in the jig after you've steam bent it?
TR: It depends on the thickness of the wood and which of our products we are creating. A thicker piece of timber will take more time to dry out after the steaming process than a thinner piece. We have a drying room at our workshop that all steam bent products enter for a minimum of 24 hours. Some dry within a few hours of this time, some take the full day.
Q: How hot does the steam have to get?
TR: Our steamers are controlled and set at 80 - 100 degrees. Technically 100 degrees is the boiling point of water, and in theory, any temperature above this would be using an unnecessary amount of energy. Our steamers take a little while to reach optimum temperature so sometimes they are loaded before hitting the 100 degrees mark.
Q: Which types of wood are best for steam bending?
TR: As a general rule, hardwoods tend to yield the best results - for us anyway. We use air dried ash and oak for our solid wood furniture products but other woods that work well include cherry, birch and maple. We also use walnut for our lighting ranges. You can steam bend soft woods (including pine, cedar and spruce) but if you were attempting this, again it would be best to use air dried wood - as kiln dried wood tends break or snap more easily during the bending process.
Q: How long do you steam the wood for?
TR: It depends on the piece of wood in question. We use different lengths and thicknesses for every product that we make, it's a kind of trial and error process! There's no set rule or calculation to be honest, it's best to experiment and keep note of what seems to work best for you.
Q: Does the timber ever splinter when you are bending it? If so how do you prevent this?
TR: Unfortunately, yes! Wood is such a natural material and each piece so different to the next. Some pieces have more knots than others, have grain run-out and/or irregular grain patterns.
The key is ideally to use wood with a straight grain (European oak for instance is renown for having a straighter grain than British, mainly due to the warmer temps and quicker growing speed) but that's not always possible.
To prevent splintering when we are attempting complex bends we support each piece of wood with a steel strap whilst it's being bent. The strap hugs the wood and supports the compression, if we don't use straps the wood can break out at different angles because of the tension it's being put under.
Q: What's the difference between a strap, a jig and a clamp? Can you explain the lingo you use?
TR: A strap is a long piece of thin steel, normally a couple of mm wide. The length of the strap will depend on how long the piece of wood you are bending is. For instance, we use longer straps to bend our Arbor Armchair than pieces like our Harlyn Mirror.
A jig is a metal or wood structure that you are bending the wood around or into, it's normally a 3D structure of some kind, a jig is made of solid material that holds its form - it's robust. We design our jigs in house, they then go to our local fabricator to be made and come back to us to be assembled.
A clamp is what you use to attach the strap to the wood whilst you are bending it and also what holds the bent wood to the jig whilst it's drying out.
Q: What's the favourite thing you and your team have steam bent?
TR: That's a good question. We've done lots of incredible projects spanning over a decade. Some of the more recent ones though would have to be our house that appeared on Channel 4 Grand Designs in 2016 and last year's Chelsea Flower Show Pavilion (below) which had an enormous steam bent bench (probably the biggest free standing structure we've built to date).
Last year we also made a reception desk for the Institute of Physics and created a bespoke planter for Horatio's Garden. That's aside from our current product ranges, which are all skilfully made by our talented team in the workshop.