Robust appearance matching with filtered component analysis

A process for preserving green colored plant tissues and in particular coniferous needles, holly and low fiber leaves such as mosses, lichens and ferns in which selected leaves are immersed in a solution comprising (by volume) 35-45% water, 20-30% 2-propanol, 5-12% propionic acid, 5-10% sulphurous acid, 5-10% formalin, 2.5-5% formic acid, 1-5% ethylene glycol, and optionally minor amounts of compounds selected from the group consisting of cupric sulphate, cupric chloride, 20-20-20 fertilizer, citric acid, DBE, magnesium sulphate, acetic acid, cupric acetate, cupric nitrate, sodium phosphate, sodium sulfite, butylated hydroxytolulene and glycerol, for a sufficient time to exchange the naturally occurring water in the tissues with the "chemical water" of the solution and thereby permanently retain and biologically fix the green color of the leaves.