This wrinkling effect can occur when paint dries too quickly, forming a surface skin before the paint underneath can dry properly. Overcoating a previous undercoat or gloss too soon can also cause this problem, as can applying oil-based coatings too quickly at low temperatures. Before attempting to smooth out the wrinkles, allow the surface to dry and harden, then rub down using wet and dry abrasive paper with warm water and detergent. Rinse thoroughly with clean water and allow it to dry before repainting. If still wet/soft then scrape off and if this is extensive, strip all off.