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Doug Neckers on Stereolithography


Stereolithography was named by Hull and his colleagues in San Gabriel, CA in 1986 – 87 to explain what he was doing in forming an additive print assembly from individual layers of materials that were shaped, and formed, using a photochemical polymerization. (I emphasize Hull and his colleagues to point out that I met four persons in that warehouse in January, 1987 one of whom, Stuart Spence, gave the impression that the name for the technology had been open for some discussion before they came up with stereolithography.  Spence and Chic Lewis were working for 3D at that time. They did not survive after sales of machines began though Chuck Hull, in particular, found this distasteful. Alan Herbert, I believe, from 3M came up with the notions of additive and subtractive modeling so that idea was not Hull’s either.) 

Hull was a single minded inventor. He managed two extraordinary things - he found a way to make the to make three-dimensional print technology work, and he – with Ray Fried – began to develop the markets. It should no go in passing that photopolymerization with polyolacrylates and methacrylates, which is what Hull was using in the beginning, was the invention of Louis Plambeck at DuPont.  Plambeck (US 3,046,127 July 24, 1962 – Photopolymerizable Compositions, Elements and Processes - ) following a patent 2,367,660 Process of Photopolymerization by Courtland Agre also to DuPont, Application December 31, 1941 who, though living in Minneapolis, assigned the patent to DuPont. In it, he described “polymerizable ethylenically unsaturated organic compounds, i. e. the polymerizaiton thereof under the influence of light.” Agre says the photopolymerization of "certain ethylenically unsaturated compounds has long been known…” but is "not yet commercial.” Kodak work from the hands of Louis Minsk in Rochester, taught polymer hardening and crosslinking with poly(vinyl cinnamate) but this technology, of low resolution, never caught on after its first generation.

What did catch on was the photopolymerization of acrylate and methacrylate monomers though there were model integrity issues with them. Hybrid photo polymerizable resins were introduced for stereolithography by Steinmann, Wolf, Schulthess and Hunziker in US 5476478, December 19, 1995 “Photosensitive Compositions.”  A hybrid stereolithography resin was a formulation with both a photopolymer formed by free radical reactions, and another formed by cationic polymerization in the same mixture. The former conveyed speed; the latter conveyed the integrity of the shape.

At this point, 3D printing has become a technology for which the outer bounds have not yet begun to be explored. I have put several  of my articles in this file. I am a photoscientist, and only expert in, or competent to comment on, photopolymerization as in SLA systems. Other technologies are cheaper; produce objects from more functional materials; can be affected at higher resolution. But I plan to keep track of the technology using photopolymerization on web site – I hope the readers will enjoy what I find. -Doug Neckers


"Doug Neckers: Pioneer in Stereolithography" from SPIE (International Society for Optics and Photonics) 2013 Profile on Doug Neckers: 


















Doug Neckers' Spectrum article in 1989:














"Chuck Hall: Pioneer in Stereolithography" from SPIE (International Society for Optics and Photonics) 2013 Profile.


"Automatic Method for Fabricating a Three-Dimensional Plastic Model with Photo-Hardening Polymer" from AIP, December 2013.


Rapid Prototyping Patent 


More 3D Printing in the News:

"3-D Printing Moves Closer to the Mainstream" from The New York Times "Bits" section, January 20, 2014. 

"3D Systems and Hershey Team Up To Deliver 3D Printed Edibles" from 3D Systems, January 16, 2014.  

"House Votes to Extend Gun Law Without New Provisions for 3-D Printed Firearms" from The New York Times, December 3, 2013.

"Plastic Kills: Undetectable Firearms Act set to Expire" from The Toledo Blade, December 3, 2013.

"3D Systems CEO Named to Fortune Magazine's 2013 Top 50 People in Business," December 9, 2013.  

"Who Made That?: 3-D Printer" by Pagan Kennedy, The New York Times Magazine, November 24, 2013. 

"Beyond 3-D Printers' Magic, Possible Legal Wrangling" from The New York Times, November 23, 2013. 

"The Expiring Ban on Guns" from The New York Times, November 19, 2013. 

"How 3-D Printers are Now Making Guns" from The New York Times "Bits"  section, March 27, 2013. 

"Live and in 3-D: Stem-Cell Printouts" in The Wall Street Journal, February 5, 2013.

"Disruption: With a 3-D Printer, Building a Gun with the Push of a Button" from The New York Times "Bits"  section, October 7, 2012.