catechu for toning cyanotypes

S_IZZO@guvax.acc.georgetown.edu
Tue, 28 Jan 1997 17:20:22 -0500 (EST)

In December there were questions about catechu. Terry King posted
a formula using it to tone platinum prints.

I found the following procedure using catechu to tone cyanotypes in
Ferric and Heliographic Processes: a handbook for photographers,
draughtsmen, and sun printers, by George E. Brown
NY: Tennant & Ward, London: Dawbarn & Ward
no date (but old, turn of century?)

cyanotype toner: Roy's Process (greenish black)
borax 70g:1000cc water
add sulphuric acid by drops till solution turns litmus paper red
add 10% ammonia till red color changes (it is faintly alkalai)
add 10g powdered catechu, shake, filter

I haven't tried this since I have no catechu.

Suzanne Izzo s_izzo@guvax.georgetown.edu