If your pieces are all sticky after 12 hours, that's an indication that the mix proportion was off. No matter your batch size, you should always mix Little Windows with 2-parts resin (Part A) to 1-part hardener (Part B). If only some of the pieces within your batch are sticky and others set up fine, that means the mixture was not fully blended. Be sure to mix for the full 2-1/2 minutes, scraping the sides and bottom of your mix cup, then allow the mix to rest for 5 minutes before pouring. This allows continued blending on a finer level, so the chemicals can begin to bond.