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Steam Bending Misconceptions Q&A with Tom

Your most-asked steam bending questions and queries answered...
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Experimental, innovative, unique. Our signature steam bending technique sits at the heart of everything we do. With so many myths, misconceptions and frequent queries about this ancient process, we caught up with Tom to answer some of your most-asked questions.

 

You must need lots of equipment…It’s not something I could try at home myself.

TR: The beautiful thing about steam bending is its simplicity – the low-tech process has been around for over a thousand years and can be adapted for small and large-scale projects. I tried steam bending for the first time at home; I distinctly remember holding a small piece of wood over a boiling kettle and tying to see how the steam manipulated the grain allowing it to twist and bend.

In its most basic terms, a steam bending set up requires a box, chamber or bag which is being fed by constant steam and of course, wood. Once the wood is steamed, just try twisting it with your hands (gloves recommended). It’s amazing that a hard piece of oak can behave like rubber having been exposed to steam for a short amount of time.

For creating more complex bends, suited to projects, there are a few options for setting the wood in its final shape (depending on the bend you want to achieve and how thick the wood is). You can use a bending jig or former to help pull the wood around and hold it in place, or even special compression straps for tighter bends to stop the wood from splitting.

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Steam bent timbers are clamped to a custom-made round wooden jig.
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Short lengths of timber and clamps are used to support a large-scale steam bent bench handcrafted from over 300 meters of solid ash wood.

It takes a very long time, from start to finish.

TR: Finding a successful method that works for you, setting up the equipment, prepping the tooling, heating up the steamers and developing jigs for designs is time consuming, but the actual time it takes to physically bend the wood into place is comparatively quick. It has to be quick - once the wood is steamed, you have a very short window to bend it into place before it cools down and becomes less pliable and supple to work with.

After the wood has been bent it needs to dry out in a really warm space for a number of days to remove the moisture content that’s created by the steam. Once dry, water marks and stains must be sanded and removed from the wood to create an even, smooth finish. As wood is a natural, organic material each piece is different; it has its own characteristics, grain pattern and markings that mean every bend requires different work to get it to the finished product stage. There’s no set time from start to finish really, there’s too many variables and every wooden product we create is entirely unique. That’s what makes it special.

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Bent pieces of wood are carried to our on-site drying room to be kept at a consistent warm temperature for a minimum of 48 hours.

You can only steam bend oak wood.

TR: You can actually steam bend lots of different woods, to different effects. Some will be more successful than others due to their moisture content, species and grain. Any temperate hardwoods can be bent and in fact, oak, which is the wood we use the most often is one of the most difficult to bend. I love bending ash wood because it’s very susceptible to the steam and creates amazing curves. Ash wood also grows fast and straight – which in turn makes the grain straight – and very enjoyable to steam bend successfully.

Do you have to have steam, or could it just be heat?

TR: There are actually many ways to bend solid wood. I’ve heard of makers wrapping wood around hot plates, but this is not as efficient or eco-friendly due to the power required to heat it. Furthermore, I’ve seen wood heated in a microwave (dangerous but quite fun!), you can also use ammonia – but I wouldn’t recommend this as it’s not a pleasant aroma! For musical instruments makers often use hot pipe bending but you still need to dampen the wood first and the process is supposedly only suitable for smaller bits of wood.

We have found bending with steam to be the most versatile and adaptable for our product ranges. It’s efficient in terms of material wastage, power usage and time…and definitely by far the most fun. The possibilities with steam bending are endless!

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Billowing steam escapes from our handmade steamer and fills our workshop space.
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Tom carefully checks the progress of steaming wood to see if it's ready to be bent around our custom jigs.
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Lengths of timber are quickly extracted from the steamer ready to be bent by our workshop team.

There is a lot of waste wood from snapping and splitting.

TR: Once you have practised and learnt the technique you become very connected to the wood and can tell how far you can push it before it’s likely to split or break. It’s very intuitive. We aim for 100% but have a 95% success rate on most bends we do.

However, I’ve spoken to countless people who have had a go at steam bending and failed; in theory it’s a simple process but there is a lot that can go wrong. It takes years of practise and understanding to get good at steam bending and know why something is not working. If you find that you’re bending with high levels of splitting, try bending at different speeds or using certain clamps in specific places to hold tension. Sometimes you may have to bend the wood as far as allows then reheat a section to allow you to push that little bit further.

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Bending particularly thick pieces of wood sometimes requires extra pressure applied in the form of wooden off cuts, which add leverage.

The wood is very fragile after steam bending.

TR: Bending wood with the flow of its grain, as opposed to against, makes it stronger and structurally sound. Steam bending was primarily used to make weapons and boats, so it’s a great process to try if you want to make something durable that’s going to last a long time.

You can get the same effect from cutting solid wood.

TR: You would need very large pieces of wood to create the same effect. Naturally this method would produce a higher level of wastage and off cuts and the joins could become structurally weak over time. Steam bending is a much more ecological alternative.

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Fluid shapes can be created using different types of jig and wood type.
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Ash wood is particularly pliable when steamed at an optimum temperature and for a long duration.

You should use a soft wood as it’s more flexible...

TR: We would argue that hardwoods bend to better effect. However, it is not that easy to generalise as a rule, some hardwoods don’t bend well at all and some soft woods bend to great effect. Certain species of wood bend much easier than others; the more open the wood grain, the easier it responds to being steamed (which makes sense as the steam can penetrate the open pores more easily).

It’s worth noting that the molecular structure in softwood is different to temperate hardwoods, so it does not bend in the same way. Tropical or softwood species do bend, but you can only create very gentle bends and even then, the failure rate is very high. The only wood that defies all of this is yew; it bends really quite nicely but is hard to come by.

Deciding what wood to steam bend will be determined by the end use: whether it will be inside or outside, how strong it needs to be, if it needs to be rot-resistant etc.

 

The wood will unbend itself straight unless its supported afterwards.

TR: Generally a solid piece of wood will retain its curve if it’s dried properly. Steam bent wood can be prone to moving slightly if it’s exposed to damp conditions – but our designs cater for this unlikely outcome by including a supported or joining section that can balance out any warping or tension.

If we create a product with an unsupported bend, we make sure that the bend severity and the wood thickness is so strong that any movement would be minimal and not effect the longevity or aesthetic of the piece.


Q&A: OUR STEAM BENDING TECHNIQUE

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.

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