TECHNOLOGY FOCUS - POLYMERS - Preferred Process: The method comprises (i) providing the two components (a) and (b) in open or closed mold, (ii) hardening the polyurethane and (iii) removing the polyurethane from the mold. The method, subsequent to step (iii), comprises: annealing the polyurethane at 80-160 degrees C; and treating the polyurethane with infrared before or after the annealing step. Preferred Components: The isocyanate content of the component (a) is 10-30 (preferably 15-25) wt.%. The component (b) is a polyether alcohol, which exhibits a functionality of 2-5, and a hydroxyl number of 350-950 mg KOH/g. The polyether alcohol is prepared by adding ethylene oxide and/or propylene oxide (preferred) to 2-5 functional alcohols. The component (b) is a mixture of at least two polyether alcohols. The component (b) comprises: (b1) a polyether alcohol exhibiting a functionality of 2-5 and a hydroxyl number of 350-950 mg KOH/g and (b2) a polyether alcohol exhibiting a functionality of 2-5 and a hydroxyl number of 50-200 mg KOH/g; or (b1) and (b3) a polyether alcohol exhibiting an average functionality of 2-8 and an average hydroxyl number of 350-500 mg KOH/g. The component (b) comprises 45-99 wt.% of (b1), relative to the total of (b1)-(b3). The amount of the components (b2) and (b3) used is 1-45 wt.%, relative to the total of (b1) and (b2). EXAMPLE - Polyol component (comprising 64 wt.% of polyether polyalcohol having a hydroxyl number of 860 mg potassium hydroxide (KOH)/g prepared by reacting trimethylolpropane with propylene oxide, and 32.1 wt.% of polyether polyalcohol having a hydroxyl number of 160 mg KOH/g prepared by reacting trimethylol propane with propylene oxide), tin catalyst, stabilizing and blocking agent (3.8 wt.%) and isocyanate (comprising trimerized aliphatic polyisocyanate based on isophorone diisocyanate and hexamethylene-1,6-diisocyanate having isocyanate content of 20.2%) were heated at 80 degrees C, mixed in a high pressure mixer, annealed at 90 degrees C and molded in a closed mold to obtain the compact, transparent polyurethane after 2 minutes.