Use Titanium oxalate
Using titanium oxalate as a post mordant will give bright to medium shades of orange. It gives a different range of shades than when alum is used as a mordant.
Dye your material without mordanting then proceed thus:-
- Dissolve the titanium oxalate with some warm water and add to the dye pot with sufficient water to cover the material being used. Stir well.
- Add your wetted material and gently heat to a temperature of 80 degrees C for an hour stirring regularly.
- Turn off the heat and allow to cool completely.
- Dry in the shade.
Titanium oxalate has a marked reaction to tannin and is popular with artists involved in botanical prints. Leaves that contain high amounts of tannin will produce a more orange/yellow result than if using alum as a mordant.
It is also more lightfast than alum.