Editing Particle board (section)

== History and development ==
The history of particleboard is unclear. The nineteenth century saw many attempts to make use of sawmill by-products, including sawdust and wood chips, by manufacturing composite boards; conceptual references to processes of manufacturing wood composites similar to particleboard date from 1887.<ref>{{cite journal |last1=Katlan |first1=Alexander W. |title=Early Wood-Fiber Panels: Masonite, Hardboard, and Lower-Density Boards |journal=Journal of the American Institute for Conservation |date=1994 |volume=33 |issue=3 |pages=301–306 |doi=10.2307/3179639 |jstor=3179639 |url=https://doi.org/10.2307/3179639|url-access=subscription }}</ref> In 1935, Farley and Loetscher Manufacturing Co. became the first plant to manufacture particleboard.<ref>{{cite journal |last1=Bucher |first1=Charles |title=Dating Twentieth-Century Buildings by Means of Construction Materials |journal=APT Bulletin: The Journal of Preservation Technology |date=2012 |volume=43 |issue=2/3 |page=75 |jstor=23317191 |url=http://www.jstor.org/stable/23317191}}</ref> A particleboard industry developed over the course of the 1940s.<ref>{{cite book|last1=Rowell M.|first1=Roger|url=https://books.google.com/books?id=Kn_RBQAAQBAJ|title=Handbook of Wood Chemistry and Wood Composites|date=2005|publisher=Taylor and Francis Group|isbn=978-1-4398-5381-8}}</ref>

In 1932, ''[[Luftwaffe]]'' pilot and inventor [[Max Himmelheber]] patented a process for making particleboard without fully impregnating wood fibers with adhesive, distinguishing it from earlier wood composites.<ref>{{Cite web|url=https://patents.google.com/patent/CH182058A/en|title = Wood-like mass and process for its production}}</ref> This particleboard could be produced with waste products such as planer shavings, off-cuts, or sawdust, [[Hammermill|hammer-milled]] into chips and bound together with a [[phenolic resin]]. Hammer-milling involves smashing material into smaller and smaller pieces until they can pass through a screen. Most early particleboard manufacturers used similar processes, though often with slightly different resins. 

It was found that better strength, appearance, and resin economy could be achieved by using more uniform, manufactured chips. Producers began processing solid [[birch]], [[beech]], [[alder]], [[pine]], and [[spruce]] into consistent chips and flakes; these finer layers were then placed on the outside of the board, with its core composed of coarser, cheaper chips. This type of board is known as three-layer particleboard.

More recently,{{When|date=February 2020}} graded-density particleboard has also evolved. It contains particles that gradually become smaller as they get closer to the surface.