The secret to successful natural dyeing of cellulose fibres, yarns and fabrics such as cotton and linen is thorough scouring. The scouring process removes natural oils, waxes and pectins from the fibre so that the dyes can penetrate the fibre more readily.
Phaeolus schweinitzii fungi produces Yellow, gold natural dyed yarns
A selection of Natural Dyes and Mordants
How To Make a Tin Mordant recipe
A simple how to recipe for making an alum mordant, used for natural dyeing
Learning to use natural dyes