Zoya Renew is formulated to thin out polish, top and base coat formulas of 3 free nail polishes. Toluene, formaldehyde and DBP are chemicals that it is now common to omit from nail varnish because of potential toxicity problems. But, without these additions, users have found their varnish is thickening prematurely. This is such a great idea from Zoya - it claims to give an extra 50% of life to your lacquer. £9.95.