sighten

From sight +‎ -en.

sighten (third-person singular simple present sightens, present participle sightening, simple past and past participle sightened)

1. (transitive, calico-printing) To add a fugitive colour to (a paste), to enable the printer to determine whether the figures are well-printed or not.
   • 1830, Samuel Frederick Gray, The Chemistry of the Arts:

     The iron liquor should be sightened with logwood.

   • 1849, Edward Andrew Parnell, Dyeing and Calico-printing, page 132:

     Annexed is a specimen of calico in this stage of the process, the mordant on which is red liquor, “sightened” with a little decoction of peach-wood or similar dye-stuff.

• sightening

• se'night, nighest, thinges, singeth, Hengist, Githens, Thesing, signeth