We represent all things Bertoia & spread the legacy of Harry Bertoia.

Harry Bertoia Foundation is a 501(c)(3) public non-profit organization. We EDUCATE and INFORM the PUBLIC about artist HARRY BERTOIA and modern art in general. We collect historical documents of Harry Bertoia and distribute appropriately. We create and expand public displays and educational programs of Harry Bertoia artwork and music. We further the legacy of Harry Bertoia. See further details at Guidestar nonprofit directory here.


Our Team of Experts:


Celia Bertoia
Director & Founder

Celia, youngest daughter of Harry Bertoia, has a background in real estate and fundraising, and created the foundation in 2013. Her biographical book, The Life and Work of Harry Bertoia, came out in 2015. She is a fine arts appraiser as a member of the American Society of Appraisers (ASA). She teaches post war art classes, and lectures widely. You will find her at the St George gallery most days.


Wilbur Springer
Chairman of the Board

A previous gallery owner and real estate appraiser, in his retirement years Bill has never stopped dealing in and learning more about fine art, especially Bertoia. His assistance in inventorying estate pieces and his years of studying the art market have imparted valuable input for the foundation.

Carl Magnusson HB dot org pic

Carl Gustav Magnusson
Board Member

A Swedish born design guru who has worked with Charles and Ray Eames, spent decades as the Director of Design with Knoll, won design awards too numerous to count, has recently reopened his own industrial design practice in New York City. His expertise not only in all forms of design, but patent and trademark issues, business practices, and marketing makes him completely useful at the foundation. It was Carl who co-founded the Knoll Museum in East Greenville, Pennsylvania in which many original Bertoias, both sculpture and chairs, plus 60+ years of other archival furniture items, are displayed.


Mary Petrilli
Board Member

Mary has held various management positions at Mattel Toys which has given her broad insight into marketing and business practice. Her insightful suggestions and new ideas are nothing less than genius. She serves as bookkeeper and secretary for the Foundation. Mary carries passionate enthusiasm for Harry Bertoia.


William Shea
Board Member

Bill Shea, Senior Industrial Designer for Knoll Product Development for ten years, recently retired from his own design, development and engineering consultancy, Shea+Latone, Inc. Bill knows nearly everything about the Bertoia chairs and is working on a book about the same. He has a bloodhound-like passion for investigation, and has an impressive network of Bertoia aficionados to call upon for assistance. Combined with his dry sense of humor, he is a welcome addition to the Board.

Glenn Adamson - photo by Dietmar Busse

Glenn Adamson
Board Member

Glenn Adamson is currently Senior Scholar at the Yale Center for British Art, and Editor-at-Large of The Magazine Antiques. A curator and theorist who works across the fields of design, craft and contemporary art, he was until March 2016 the Director of the Museum of Arts and Design, New York. He has previously been Head of Research at the V&A, and Curator at the Chipstone Foundation in Milwaukee. His publications include Art in the Making (2016, co-authored with Julia Bryan Wilson); Invention of Craft (2013); Postmodernism: Style and Subversion (2011); The Craft Reader (2010); and Thinking Through Craft (2007).


Shannon Stratton
Board Member

Shannon is currently the Executive Director of the Ox-bow School of Art. She has acted as curator, writer, and educator at various impressive locations included the Museum of Arts and Design, NY. Her broad connections and sharp insights have been a boost to the Foundation.

Roger Wall
Board Member

Roger, just like his name, is straightforward and simple but very effective. He is the President of Spinneybeck, a home furnishings manufacturing company of natural materials who works closely with Knoll and other major furniture companies. His negotiating experience, contract knowledge and general business acumen have served the Foundation very well.


Marin R. Sullivan, PhD
Catalogue Raisonné Director

Director of the Harry Bertoia Catalogue Raisonné Project, Dr. Sullivan is a Chicago-based art historian and curator. She is very accomplished as a scholar, does an amazing job as CR Director, as well as a fine human being. Sullivan was recently Assistant Professor of Art History at Keene State College in New Hampshire, and also served as the Henry Moore Post-Doctoral Research Fellow at the University of Leeds. She is the author of Sculptural Materiality in the Age of Conceptualism (2017), numerous articles in publications including Art History, History of Photography, the Journal of Curatorial Studies, and Sculpture Journal, and is co-editor of Postwar Italian Art Today: Untying ‘the Knot’ (2018). She recently published Alloys: American Sculpture and Architecture at Midcentury, which has been supported by fellowships from the Smithsonian American Art Museum and the Crystal Bridges Museum of American Art.


Frequently Asked Questions:

How do I go about certifying the authenticity of a Harry Bertoia work of art?

Let’s find out exactly what your needs are.  Are you looking for:

  • A casual opinion of whether or not you have (or are considering purchasing) a real Bertoia?
  • An off-the-cuff opinion of what your Bertoia might sell for at a gallery or at auction?
  • An official Certificate of Authenticity from the HarryBertoia Foundation?
    Each certificate is the product of detailed research and expertise, and establishes the art as an authentic Harry Bertoia. Fees for authentication begin at $400.
  • A professional appraisal of value from our in-house Bertoia expert and fine art appraiser?
    An appraisal determines the type of valuation necessary for your specific situation, i.e. estate taxes, divorce settlement, insurance coverage, possible future sale, etc. and produces a 20 to 40 page report detailing both the current market environment, and the artwork and its value. Comprehensive analysis and explanation pertaining to your situation and the piece are included. The fee for an appraisal can range from $500 to $5,000 or more, depending on the number of pieces in your collection and the depth of research necessary for each piece. Click here to visit Fine Art Appraisal for more information.

We hope this helps you determine what you need. All of the above are available through the foundation. If you are looking for an auction house or gallery to sell your piece, browse our resources.

Let us know how we can help you further by emailing our staff at Info@HarryBertoia.org to set up an initial consultation.


We would be happy to authenticate your Bertoia art (if everything looks to be in order, of course). The base fee is $400. If further or extensive research is required, we will discuss an additional hourly fee. We can often work from high resolution photos but in some cases will need to see the piece in person. It can be shipped to us or you can opt to pay for our travel to you. Insurance is your responsibility. We will send an invoice via PayPal (or you can pay by check). You will receive a formal document and any related archival files (if available).​

An unsigned electronic version will be sent followed by a signed hard copy.​ We use our best judgement and thorough research but you should be aware that there is still a chance of error.

We will need the following via email:

  • Dimensions to closest 1/4″: total height, base width and length.
  • For Sonambient, number of rods and configuration of rods (i.e. 81,9 x 9 or 30,single row of 30)
  • Type of metal, if known, of rods, tops (if any) and base
  • Date created, if known
  • Any damage, scratches, marks; condition as you see it
  • Provenance, history of ownership as far as known
  • Why you believe it to be a Bertoia
  • Copy of receipts or related documents, if any
  • Photos, hi-res, from several angles and bottom, front, side and back and detail of welds
  • Any other pertinent details important to the piece
  • Your mailing address and correct spelling of your name

Thank you

How do I go about getting a Bertoia work of art repaired or cleaned?

First, congratulations on your good taste and wise investment!

How to best care for your piece depends on the condition it is in. Click on any of the sections below to learn more.

Dust & Grime

Unless you have a fragile or delicate piece, gently washing the sculpture will not harm it. Take it outside, turn on your spray hose and rinse it down. Immediately dry the metal thoroughly and completely with a clean cloth. If it is still not clean to your satisfaction, take a dab of mild dish soap (such as Ivory Liquid) and mix with warm water. With an old toothbrush or other soft-bristle brush, lightly scrub your sculpture. Rinse with plain water and dry immediately. Most metal sculptures are fairly robust. Unless you use intense chemicals, you probably won’t hurt it.

Discoloration, Rust, White Spots

The foundation recommends the cleaning product CLR (Calcium, Lime, Rust) to remove light spots. Follow the instructions on the container. Do not let it sit on the surface for too long as it may begin to eat away at the metal or the patina. Do not use sandpaper or a metal brush – it is too rough and will destroy the surface of the metal. If your sculpture has acquired the green patina of weathered copper or bronze, applying CLR as directed should remove it, if desired.

Non-Patinated Metal

If you have a sounding sculpture that was once shiny and bright but has darkened considerably, you may wish to shine it up again. If you plan to sell it, place it in an exhibition, or display it publicly in the near future, we recommend that you check with your auctioneer or museum director before polishing. The metal polish MAAS (available at MAASinc.com) has worked well for us. Follow the package directions. Make sure you get all the polish off and rub with a soft, clean cloth.

Centennial Table Tonal

These limited edition sculptures are not patinated and can be polished as desired, as specified above for non-patinated metal. If your piece has collected dust or pet hair between the rods, take a strip of cloth or Q-tip and slide it back and forth until the dust is removed.

Bent Rod

If a rod of a tonal has accidentally been bent out of place, disrupting the orderly placement, you can attempt to bend it back with patience and gentleness. Carefully pull the out-of-place rod(s) in the opposite direction, slightly past the desired original location, until it stays in the right spot. Make sure you don’t mistakenly include a previously straight rod, and do it in small increments. If the rods are too damaged you will need to have a professional repair it.

Professional Repairs

If your art is badly damaged or in need of serious conservation, there is hope. Look for capable metalsmiths or art conservators in your area, or contact the following experienced Bertoia repair sources:

We have found good results working with both companies.


If desired, microcrystalline Renaissance Wax may be added as a protective coating. Many museums use it. The wax does not collect dust, protects your piece, and also prevents age patination.

How do I identify a Harry Bertoia chair?


Harry Bertoia (1915-1978) moved to Pennsylvania from California to work for Knoll in 1950. Knoll is the manufacturer and copyright holder of all Bertoia chairs. Chairs, based on steel grid wire forms, were designed by Harry Bertoia between 1950 and 1951 and further developed for production by Harry and the development team consisting of Richard Schultz, Don Pettit and Bob Savage in 1951 – 1952. They were first introduced in December 1952, and have enjoyed steady continuous production since 1953. To state the obvious, nearly all products that have been in production for over 63 years undergo evolutionary changes over time.  Most are a response to field failures, structural improvement or cost reduction.  Others are a response to external forces.

For the sake of discussion, one can consider all Knoll Bertoia chairs as being either early style (1986 and earlier) or late style (1986 and later).  Prior to 1986, all Bertoia chairs were manufactured in East Greenville, Pennsylvania, or overseas by Knoll subsidiaries or under license.  At various times, Bertoia chairs were manufactured in Argentina, Belgium, Finland, France, Germany, Italy, Japan, Sweden and Switzerland.  All chairs of pre-’86 manufacture are very similar and are often only distinguishable by the wire diameters used (close metric diameter equivalent to US standard wire gauges.) See Photo 1 with yellow tags. It must be noted that, since foreign-made Bertoia chairs were never imported to the US, that it is very unlikely to encounter them here in the US.

All chairs made before 1986 are characterized by lightness and transparency.  Harry liked to think of his chairs as being “mainly made of air.”  That changed when the manufacture of the entire Bertoia line was shifted to Italy. At that time, the collection was retooled and major changes were made. Most obvious was the significant increase in wire diameter used throughout which changed the character of the chairs from transparency to form. See Photo 2.

PHOTO 1Note the balanced corner radius as well as the thin wire diameter (“mainly made of air”) on this early style side chair. Compare this with the thicker wire diameter of the chair in the next image.

PHOTO 2Note the thicker wire diameters of the 1986+ Italian made chairs of the late style, and the horizontal nature of the upper corner cells. Compare the light and transparent early chair with the thicker-wired form chair post 1986. All authentic Knoll Bertoia chairs have the single rim wire.

Other changes include altering the seat-back angle, the addition of a “waterfall” at the front edge and the use of the “paperclip-type” base connectors.

Many other minor changes have taken place over the years.  Most of the comments below are specific to the 420 Side Chair but apply to other models as well. These include:

  • GLIDES – Various glides have been used over the years… or no glides at all.  The first ones were extrusions that snapped on (and unfortunately snapped off).  Later ones are injection-molded with an integral pin that is driven into a blind hole on the bottom of the base.
  • “KNOLL” STAMP – In 2004, Knoll began to discreetly stamp the word “Knoll” on the upper part of the base.
  • UPHOLSTERY – All chairs are available with or without upholstery, either in the form of a seat pad or fully upholstered.
  • LINE ADDITIONS – During the 1950s and 60s, a number of additions were made to the original scope.  These included the 427 fiberglass version of the 420 shell, the 425 (child-size 420 chair), the 426 (baby-size version of the 425, and the 428 barstool (in two heights).  During the 2000s, two more designs were added.  The Asymmetric Chaise, which was part of the original scope but never produced, was finally put into production in 2005. In addition, a new scaled-down child’s version of the 421 small diamond chair (never part of the original scope) was also introduced.  Finally, an injection-molded polypropylene version of the long discontinued 427 shell (side chair) was reintroduced in 2016.

Tips for recognizing authentic Knoll chairs

Despite the evolutionary and more revolutionary changes (newer Italian production) that have taken place over the years, it’s surprisingly easy to spot the originals.  While the comments below are specific to the 420 side chair, they generally apply to the others as well.  We look at two places which 99% of the time positively identify genuine Knoll chairs from the knock-offs.

First is the upper back.  On the Knoll chairs, the top basket wire is a fair curve that mimics the curvature of the top of rim wire.  The top corners are perhaps the most critical clue.  The corner radius is neither too “soft” nor too “tight” (compare to above photos of Knoll chairs for a reference).  Also, the “cell” described by the basket wires (both horizontal and vertical) and the rim wire at the top corner is horizontal in character (very unlike nearly all knock-offs).

Second is the base.  The inside bend radius is very tight on all Knoll chairs.  A 1/2” diameter dowel should nest neatly on the inside of any base bend (knock-offs have a much more generous bend radius.)

Another detail on the Knoll chairs is that the grid wires are cut at an angle (some knock-offs have a straight blunt cut of the grid wires). See Photo 3.

PHOTO 3The “paperclip type” base connector, angle-cut grid wires, and the front rim wire on top of grid wires in a “waterfall” identify an authentic Knoll Bertoia chair.

Tips for identifying a knock-off

It’s truly amazing that any company choosing to knock off an iconic product such as the Bertoia collection should be so sloppy in detail and make so many changes that scream knockoff!  But such is the case.

Descriptive words such as “Bertoia style,” “in the manner of Bertoia,” “inspired by Bertoia,” or “Bertoia reproduction” are a sure tip-off that it’s a copy. If the word “Knoll” is mentioned, it is still no guarantee as to its authenticity.

Many manufacturers of knock-offs utilize a “double rim-wire.”  While the double rim-wire was used for small number of 420 production chairs in early 1953, they were quickly replaced with a single larger diameter rim-wire.  Very few double rim chairs were shipped to customers.  Note that a double wire rim has always been used on the ottoman and asymmetric lounge and a partial double-rim has always been used on the 423 “Bird chair.”  Every new double-rim side chair is a knock-off.

PHOTO 4An early double rim wire
original, rarely found today.

PHOTO 5From left: 1953 double edge wire, 1953 double edge two tone thick plastic with original seat pad, early black thin wire, another early black thin wire with wide
clip connectors, white with short leg extensions, post 1986 with front edge waterfall and thicker wire – all authentic Bertoia side chairs.

The top corner tells a lot.  Most knock-off side chairs have “soft shoulders”; a much larger corner radius that lacks definition.  The top corner cell is nearly always more square or vertical than horizontal (as it should be).  Also, the top (horizontal) basket wire is often visually clumsy compared with the Knoll version. See Photo 5.

Finally, the base.  All knock-offs have a much larger bend radius than the authentic Knoll versions.  It must be noted that all pre-1986 chair bases consist of two pieces (upper and lower) and are resistance welded in an overlap condition.  Most knock-offs are “butt welded” with no overlap.  It must be noted that some Italian made Knoll chairs are made in a similar way but the welds are much neater.

It’s quite instructive to simply Google “Bertoia furniture knock-offs” and compare with pics of the real Knoll chairs.

PHOTO 6 Modern double rim wire plus no base/leg
overlap and an overly generous corner radius;
all sure signs of a current knock off.

A few other notes

chair_article_photo_9_compactEames vs. Bertoia There seems to be some confusion on the Eames wire chair vs. the Bertoia wire chairs. Harry Bertoia worked with Charles Eames in the late 1940’s and was toying with, and making drawings of, the wire grid concepts. Eames carried this idea to fruition. Below is the Eames wire chair first produced by Herman Miller in 1950. The Bertoia chairs have a similar same wire grid concept but came out in 1952.

PHOTO 7: Eames wire chair, not to be confused with the Bertoia wire chairs (photo courtesy Herman Miller)

Why is authenticity important? Why is it important to get an authentic designer chair? Why not get a reproduction that looks roughly similar and costs half the price? There are several reasons to get the real deal when it comes to designer furniture. First of all, by purchasing from the authorized manufacturer you are honoring the designer and getting a piece of his energy. He (Harry Bertoia or any designer) was an artist and had specific intentions for his design. The authentics are faithful to the designer’s original vision, while knock offs are not. Secondly, you will get a quality product with customer service behind it if you buy the authorized models. We’ve heard horror stories of offices or homeowners buying the cheap versions and being disappointed in the durability and comfort of their purchases. Welds fail and the chairs are simply not comfortable. And finally, an authentic designer purchase will hold its value much better than a knock-off. One Knoll chair is always more desirable than many China-made or European copies. Would you rather have one Picasso or twenty photocopies of a Picasso?

KNOLL or HarryBertoia Foundation? If there are questions about chair care, photos rights, replacement parts, manufacturing or prices, please contact your nearest Knoll representative (knoll.com). The HarryBertoia foundation (harrybertoia.org) can help with history, timeline, design aspects, Harry’s philosophy and non-material questions. For assistance on authentication of rare or unusual Bertoia chairs, contact the foundation and we will direct you to our expert Bill Shea. A fairly comprehensive chair history can be found in Celia Bertoia’s book, The Life and Work of Harry Bertoia, 2015, Schiffer. An even more extensive history of Bertoia chairs is being compiled by Bill Shea right now.

We hope these pointers will help you in your search for authentic Bertoia chairs.

Bill Shea, formerly Senior Industrial Designer for Knoll Product Development, recently retired from his own design, development and engineering consultancy, Shea+Latone, Inc.  Celia Bertoia is the Director of the HarryBertoia Foundation and author of The Life and Work of Harry Bertoia.