A pair of knitting needles, 1940s
Source
MoDiP.
History
Apparently unused with original paper binding still in place.
Material
The needles are made of the featured material, casein formaldehyde. The end pieces are of urea formaldehyde.
Degradation
Warped.
Degradation typical of the material not visible in this example
Can crack if kept in too dry conditions.
Treatments
Casein is a relatively stable plastic but requires higher humidity storage than other materials as water acts as a plasticiser. Storage of these needles in a humid environment might help them straighten out. Unlike with other plastics it would not do any damage.
Display and storage
No special requirements except ideally to be kept in higher humidity than other plastics (e.g. 55-65% RH). Make sure it is not very dry (e.g. under 40% RH).
Downloads
Images from March 20151.61 MB
Images from September 20151.12 MB
Images from March 20161.03 MB
Images from September 20161.06 MB
Images from March 20171.01 MB
Images from September 20171.07 MB
Images from March 20181.07 MB
Images from September 20181013.1 KB
Images from March 2019427.67 KB
Images from September 2019520.29 KB