Editing Casein (section)

===Glue===
[[File:Casein glue preparation.jpg|thumb|upright=3|Preparing casein glue]]
Casein-based glues are formulated from casein, water, and alkalis (usually a mix of [[hydrated lime]] and [[sodium hydroxide]]). Milk is [[skim milk|skimmed]] to remove the fat, then the milk is [[sour milk|soured]] so that the casein is precipitated as [[milk curd]]. The curd is washed (removing the [[whey]]), and then the curd is pressed to squeeze out the water (it may even be dried to a powder). The casein is mixed with alkali (usually both sodium and calcium hydroxide) to make glue. Glues made with different mixes of alkalis have different properties. Preservatives may also be added.<ref>{{cite book |vauthors = ((Forest Products Laboratory, Forest Service, US Department of Agriculture)), ((University of Wisconsin--Madison)) |title=Casein glues : their manufacture, preparation, and application - Indiana State Library |date=April 1961 |url=http://link.library.in.gov/portal/Casein-glues--their-manufhttps://ir.library.oregonstate.edu/dspace/bitstream/1957/882/1/FPL_280ocr_rev.pdf |archive-url=https://ghostarchive.org/archive/20221009/https://ir.library.oregonstate.edu/dspace/bitstream/1957/882/1/FPL_280ocr_rev.pdf |archive-date=2022-10-09 |url-status=live |series=Information Reviewed and Reaffirmed | volume=280| language=en}}</ref><ref>{{cite web |title=Chemistry Casein Glue - Activity |url=https://www.teachnlearnchem.com/Matter_and_Energy/PDF/casein%20glue.pdf}}</ref>

They were popular for woodworking, including for aircraft, as late as the [[de Havilland Albatross|de Havilland ''Albatross'']] airliner in 1939.<ref name="fpl.fs.fed.us">{{cite web|url=http://www.fpl.fs.fed.us/documnts/fplrn/fplrn158.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.fpl.fs.fed.us/documnts/fplrn/fplrn158.pdf |archive-date=2022-10-09 |url-status=live|title=Casein Glues: Their Manufacture, Preparation, and Application|date=1967|publisher=[[United States Department of Agriculture|USDA]]}}</ref><ref>{{cite web|url=http://www.soyinfocenter.com/HSS/if_laucks_and_soybean_glue.php|title=Pioneering Soy Protein Companies: I. F. Laucks, The Glidden Co., Rich Products, Gunther Products, Griffith Laboratories| vauthors = Shurtleff W, Aoyagi A|date=2004|work=soyinfocenter.com|access-date=3 Sep 2015}}</ref>

Casein glue is also used in [[transformer]] manufacturing (specifically transformer board) due to its oil permeability.<ref>{{cite web|url=http://www.weidmann-electrical.com/en/markets-a-products/board/cellulose-based/laminated-board|title=Laminated Board|date=2011|publisher=WICOR HOLDING AG|archive-url=https://web.archive.org/web/20111222012222/http://www.weidmann-electrical.com/en/markets-a-products/board/cellulose-based/laminated-board|archive-date=22 December 2011|url-status=dead|access-date=11 Oct 2012}}</ref>

[[Elmer's Products|Elmer's Glue-All, Elmer's School Glue]] and many other Borden adhesives were originally made from casein. While one reason was its non-toxic nature, a primary factor was that it was economical to use. Towards the end of the 20th century, Borden replaced casein in all of its popular adhesives with synthetics like [[Polyvinyl acetate|PVA]].

While largely replaced with synthetic resins, casein-based glues still have a use in certain niche applications, such as laminating fireproof doors and the labeling of bottles.<ref name="fpl.fs.fed.us"/><ref>{{Cite book|title=Coatings Materials and Surface Coatings|vauthors=Lambuth A|publisher=CRC Press|year=2006|isbn=9781420044058|veditors=Tracton AA|pages=19-7–19-11|chapter=Soybean, Blood, and Casein Glues|chapter-url=https://books.google.com/books?id=HhUOI1-hhjYC&pg=SA19-PA7}}</ref><ref>{{Cite book|title=Tappi PLACE Division Conference|vauthors=Forsyth RS|publisher=TAPPI|year=2004|isbn=1595100628|location=Atlanta, Ga.|pages=33|chapter=Waterborne Adhesives for Bottle Labeling|oclc=57487618}}</ref> Casein glues thin rapidly with increasing temperature, making it easy to apply thin films quickly to label jars and bottles on a production line.<ref>{{cite web |title=Casein glues |url=https://www.intercol.info/en/?page_id=85 |website=Adhesives}}</ref>