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Wired - The Bertoia side chair

Updated: Nov 20, 2023

Originally designed in 1951 the model 420 wire side chair formed part of a series of chairs designed by Harry Bertoia for Knoll Associates. It was introduced in 1952 and became an instant success; and has been in constant production ever since. Here we celebrate 70 years of the side chair, the most famous wire chair ever created, and look back at its design, production and place in design history.

Set of 6 Bertoia wire chairs

Bertoia side chair - at a glance

Designed in 1951 by Italian American designer Harry Bertoia.

Part of a collection of 5 wire chairs and a slatted wooden bench for Knoll Associates.

Constructed of heavy gauge steel wire rods, teased, curved and welded into a lattice framework.

Open free flowing, sculptural form that is both lightweight and strong.

…and looks a little bit like a repurposed shopping trolley.

The Man

Harry Bertoia (pronounced “Ber-Toy’a”) was born in San Lorenzo d'Arzene, Pordenone in the North of Italy in 1915 and moved to Detroit when he was just 15 years old. Over the next 7 years he studied art and design at various institutions and also excelled as a jewellery maker. In 1937 he enrolled at The Cranbrook Academy of Art, and although he had no idea at the time, this turned out to be the pivotal moment in his life that set him on the path to greatness. At Cranbrook he met a number of key future 20th Century designers including Eero Saarinen, Charles and Ray Eames (who’s wedding rings he designed) and also Florence Knoll.

His interest and obvious talent in working with metal led to Cranbrook inviting him to reopen the metal work department there in 1939. He taught metal forming and welding techniques before eventually moving to California in 1943 with his new wife, Brigitta Valentiner. Once happily settled in the sunshine he took up a position working with the Eames’ on creating plywood prototypes and to start experimenting with sound sculptures. His true calling was as a sculptor and artist, but he had to wait a further 13 years to settle into his groove.

Portrait picture of Harry Bertoia

The project in California didn’t work out as planned and by the late 40s he was starting to get disillusioned with his position there. In 1950, he was invited to move to Pennsylvania by Hans and Florence Knoll to work within their studio where he was given free rein to do, literally, anything he liked. There was no pressure or commitment at all, it just seemed that the Knoll’s knew he would produce something of value if he was given the opportunity; and sure enough he did. From 1950-1952 he designed five wire chair pieces that became known as the Bertoia Wire Collection – but in actual fact there were 6 because many people overlook the beautiful slatted wooden and steel bench he created at the same time.

Harry Bertoia for Knoll Associates five wire chairs

The chairs were: the Diamond Chair, Side Chair, Bar Stool, Bird Chair and the Asymmetric Chaise. Note that the Asymmetric chaise was only prototyped at that time and did not go into full production until 2005; long after Bertoia’s death in 1978.

Harry Bertoia for Knoll Associates wood and wire slatted bench

But perhaps the most astounding thing you’ll ever learn about him is that he only ever designed one set of furniture in his life, and then gave it all up.

The Chair

It’s occasionally been rather unkindly referred to as ‘the shopping trolley chair’ and as the metal shopping trolley was invented in 1937, with the full on slide and stack model we know today being introduced in 1946, you can see why. There’s no doubt that the resistance welded (spot welding) lattice framework and construction method influenced both the Charles and Ray Eames 1951 DKR chair as well as the model 420.

Whereas the Diamond and Bird Chairs had swooping, fluid lines the side chair and bar stool had a more utilitarian form. At a time when the vast majority of chairs were still being produced in wood, metal was Bertoia’s material of choice. He considered it be both more practical and flexible, attributes that allowed him to create a wire grid concept that he could shape at will. This not only allowed him to generate a range of free flowing designs made of woven metal but also allowed him to create sculptural forms that whilst slight, also had great structural integrity.

Construction method for Bertoia and Knoll wire chairs

As he said at the time "If you look at these chairs, they are mainly made of air, like sculpture. Space passes right through them."

He had many years of experience welding metal in all its forms; from sheet metal to rods and wire. This not only helped him to conceive of the chairs but to also devise the production jigs to allow his own form of practical art to be replicated.

The other major advantage of metal, although not obvious until you think about it, is that it's timeless.

Metal is not associated with a particular era (other than the 20th and 21st Centuries) in the way that fashion in wood furniture design is. For example we think of oak as 18th and 19th century, burr walnut as Art Deco and teak and rosewood as predominately mid century. There's therefore no doubt that this is one of the major reasons why his designs have enjoyed such longevity.

However, once the initial design went into production it soon became apparent that like buses, having waited a lifetime for a wire chair to come along, two arrived at the same time…

The Rivalry What started out as a friendship turned into a rivalry that some believe was the reason why Bertoia turned his back on furniture design in the mid 50’s. Charles, Ray and Harry had known each other from their Cranbrook days and whilst he was a teacher there Charles Eames was director of the Department of Experimental Design, so had seniority. The three later collaborated on the Eames’ project at Evan’s working on plywood moulding techniques, but it was very much as employer and employee, which didn’t sit well with young designer. This came to a head when Harry, having played a major part in the design of the shell for the Eames Lounge chair (LCW), felt that his contribution had been overlooked in the credits for the chair design and left shortly after.

They were not to meet again until after he had started at Knoll and Charles Eames accused him of having copied elements of the design of the Eames DKR wire chair that was launched in 1951. This resulted in a law suit between Herman Miller (the manufacturer of the Eames wire chair) and the Knolls, who produced Bertoia’s version. The main element of contention, apart from the similarity in using wire rods in the design, was the use of a double wire rim to enclose the ends of the metal filaments – a detail that had been patented by Eames. As such Herman Miller won the case and the Knoll team (which also included an up and coming Richard Schultz) had to change the design of all their wire chair variants to eliminate the double wire rim.

Eames DKR and Bertoia 420 double wire rim

The Truth

It’s impossible to know the sequence of events for sure. What is clear is that that Charles and Ray Eames were a powerhouse design team who created numerous unique concepts that have stood the test of time. That’s not to say that leaders in their field don’t occasionally ‘borrow’ ideas from their contemporaries. However, it’s known that they were working on metal frame designs to aid them in creating their fibreglass chairs as far back as 1946. For example, the La Chaise prototype, which premiered at MoMa in 1948, was known to have been initially constructed with a wire structure, and it does bear a striking resemblance to Bertoia’s Asymmetric Chair designed much later in 1952.

On the flip side Bertoia was also a person with a highly creative mind and it is possible that two people can have the same idea at the same time, especially when working with new materials. He also had extensive knowledge of metalwork and in that respect had far more experience of metal structures than either of the Eames'.

In many respects the issues highlighted by Eames are very reminiscent of the legal wranglings between Mart Stam and Marcel Breuer over the design of the tubular metal cantilever chair back in the 1920s. Both came up with virtually identical designs in the same year, although it was later decided that Stam had precedence.

The New Design

Eames/Herman Miller winning the court case was a bitter pill for him to swallow given their history. However, as can often be the case, triumph can come out of adversity and the new design adaptation resulted in an improved aesthetic. The double wire rim on the DKR is a practical resolution to how the wires were terminated at the edge, but it’s not an elegant one as it broadens the profile. On this basis the Knoll team had to find a new way of finishing the wires at the edge and also attaching them to a single rim.

They did this by changing two elements: the first was the thickness of the perimeter wire, and the second was how the cross wires were terminated. The only way to do it effectively, without potentially resulting in a sharp edge, was to weld the wire end and then to file it to a smooth chamfer. The result was a more refined form that looked lighter and more sophisticated than the Eames chair; and it also became a key way to identify an original.

Welding technique for Bertoia wire chair

Fake or Fortune?

Well, they’re not worth a fortune, but a good vintage set will still set you back a few bob; so how do you tell an original? Post 2004 all Bertoia wire chairs had (and still have) a Knoll stamp embedded into the stretcher on the back of the chair, so that’s pretty easy to spot. But once you’re looking at the vintage versions of the chair things get more confusing. This is because the side chair has not only evolved in design over the years but has also been produced in 10 different countries. This means that not only has the gauge (thickness) of the metal changed (pre 1986 and post) but also the base and seat connectors can have one of three different ‘official’ design configurations AND the wires can terminate both over the top of the perimeter wire at the front or under, as both are official variants.

Bertoia wire chair chamfered edge profile

That said there are three main aspects of the design that has never changed: these are the radius of the top corners and radius of the sled base curves - and of course the chamfered edges on all the perimeter wires, courtesy of the Eames and Herman Miller law suit. I won’t bore you with the exact angles and descriptions but after a while you know when one is ‘right’ or not. Further details on how to identify an original Bertoia wire chair can be found on the Harry Bertoia Foundation website HERE.

What's wrong with it?

Put bluntly; waffle butt! Although the chair is ergonomically designed and is inviting to sit in, it’s not great for extended periods without seat pads. After a while the wire does dig into your behind and whilst you can buy official Knoll seat pads to add some comfort they are eye wateringly expensive. If you’re therefore picking up a set 2nd hand without pads have a look on Etsy or Ebay for cheaper alternatives, with a good set only you'll know the difference. The most comfortable option is the full seat covers with a foam insert, but then you lose the entire aesthetic of the chair as it becomes a more solid form rather than the light and airy structure Mr. Bertoia originally intended.

The other major problem on vintage models, especially pre ’86 before the wire gauge was increased, is broken wires and welds – plus corrosion on the chrome versions and flaking of the coating on the white and black variants. All these issues can be repaired, but at a significant cost as the coatings need to be stripped first and the only effective way to repair the welds is with silver solder - which is more what an experienced jeweller does rather than a traditional welder. Broken wires are more problematical as this is likely to have led to distortion of the frame profile which is not easy to fix. Unless these are repaired with skill and precision you'll end up with a wonky chair as the rods nearly always break on the base connection joints where they are under the most stress.

What's right with it? The aesthetic and durability, but also its presence and it’s iconic pedigree. It’s a chair that was cool in the 60’s, was funky in the 70’s and rocked the 80’s; it's such a pure and simple piece of design that it's still as relevant today as it always was.

The chair seems to have a chameleon like presence that enables it to blend with a huge variety of decors and settings, making it one of the most used, and recognised pieces of mid century furniture ever designed. Interior designers also love it because the wire frame not only gives the impression of space but casts dynamic shadows in light.

Bertoia wire chair dining table a dining room set

All that said, it’s easy to pass this chair by and not give it a second glance. And that’s not because it’s not worth your attention, but only because it’s been such an omnipresent piece of design over the last 70 years that it’s likely that you’ve already seen it a 100 times. You’d therefore be forgiven for thinking that it’s just a piece of cheap mass modern design; but it’s so much more than that, plus at around £1,000 a pop for a new original, it’s actually more expensive than entire suite of furniture from Ikea.

Harry Bertoia collage showing his art and sculpture

Bertoia after Knoll Bertoia was always at heart an artist and we were lucky that the Knoll’s fostered his potential to design furniture first; albeit for only 2 years. By 1956 the rights to his designs and all the potential future royalties to them were rolled up into a generous lump sum payment from Knoll Associates. The money allowed him to buy a Pennsylvanian farmhouse which gave him the space to pursue his love of art. He stayed there until his death in 1978 working on his metal and wooden sculptures, paintings and Sonanbients.

Unlike most artists Bertoia did not sign or title his artworks, believing that they were part of the universe that God designed. His work can be found in a number of museums around America including the Smithsonian. Occasionally his artwork and sculptures come up at auction and usually sell for 10’s of thousands; and justifiably so.

As Knoll historian Brian Lutz once said;

“Bertoia’s paintings were better than his sculptures. And his sculptures were better than his furniture. And his furniture was absolutely brilliant.”

David Rokov - November 2023

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Amanda Jane Wilde
Amanda Jane Wilde
Jan 07
Rated 5 out of 5 stars.

Great read & there's also some added insight from Bertoia himself on the design process for the chair at the bottom of the Knoll website page... 😊


Dec 23, 2023
Rated 5 out of 5 stars.

Insightful and informative, this is a fascinating read by someone who clearly knows his stuff!


Dec 11, 2023
Rated 5 out of 5 stars.

Love this. You really bring everything to life!


Dec 01, 2023
Rated 5 out of 5 stars.

Fascinating and honest review of this love it or loathe it design classic. Who knew a simple wire chair could have such an interesting and turbulent history! Excellent read.


Nov 20, 2023
Rated 5 out of 5 stars.

Another enjoyable and very informative read. I really appreciate the objective view provided, including the plus/minus points to be aware of. It's great to be able to get the story behind the design, which neatly fills in the gaps (literally!) of the Bertoia side chair.

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