Dyer's knotgrass

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Knotweed Polygonum spp.


A natural dark blue dye obtained from the Polygonum tinctoria plant native to China, Japan and Manchuria. The colorant in dyer's knotwood is Indigotin. Traditionally in Japan, cloth was dyed in a hot water solution containing knotgrass and millet jelly (Mizuame) after which it was dipped in cold water to precipitate the indigotin (Shimoyama et al 1996).

Synonyms and Related Terms

knotgrass blue; knotweed; ai (Jap.); Polygonum tinctoria; pileurt (Dan.); Knöteriche (Deut.); renouée (Fr.); duizendknoop (Ned.); rdest (Pol.);

Knotweed Polygonum spp.

Resources and Citations

  • H.Schweppe, "Indigo and Woad", Artists Pigments, Volume 3, E. West FitzHugh (ed.), Oxford University Press: Oxford, 1997.
  • S.Shimoyama, Y.Noda, S.Katshuhara, "Non-Destructive Analysis of Ukiyo-E Prints" Dyes in History and Archaeology, No.15, Paper presented in Manchester England, Nov. 1996.
  • Helmut Schweppe, Schweppe color collection index and information book