Liquid hardening

A curable liquid medium comprising:

• a) from 1 to 90 wt % of an alkyd-based resin;
• and,
• b) from 0.0001 to 0.1 wt % of a siccative, wherein the siccative is an iron or manganese complex of a tetradentate, pentadentate or hexadentate nitrogen donor ligand, wherein the ligand is:
• wherein each R is independently selected from:
• hydrogen, F, Cl, Br, hydroxyl, C1-C4-alkylO—, —NH—CO—H, —NH—CO—C1-C4-alkyl, —NH2, —NH—C1-C4-alkyl, and C1-C4-alkyl;
• R1 and R2 are independently selected from:
• C1-C24-alkyl,
• C6-C10-aryl, and,
• a group containing a heteroatom capable of coordinating to a transition metal;
• R3 and R4 are independently selected from hydrogen, C1-C8 alkyl, C1-C8-alkyl-O—C1-C8-alkyl, C1-C8-alkyl-O—C6-C10-aryl, C6-C10-aryl, C1-C8-hydroxyalkyl, and —(CH2)nC(O)OR5
• wherein R5 is independently selected from:
• hydrogen, C1-C4-alkyl, n is from 0 to 4, and mixtures thereof;
• and,
• X is selected from C═O, —[C(R6)2]y- wherein Y is from 0 to 3 each R6 is independently selected from hydrogen, hydroxyl, C1-C4-alkoxy and C1-C4-alkyl.