Working with and casting resin
Resin is fast and versatile, but moisture, ratio, bubbles, exotherm, fillers, and cure conditions matter.
Casting resin turns a liquid system solid through chemical reaction. Polyurethane, epoxy, polyester, and acrylic-mineral systems differ in viscosity, working time, strength, odor, UV behavior, moisture sensitivity, and mold compatibility.
Control the variables
Measure by the specified weight or volume ratio. Mix thoroughly, scrape the container, and pour within working time. Warm material flows differently. Moisture can foam urethanes. Large masses can generate dangerous exothermic heat.
Pressure compresses bubbles; vacuum removes entrained air before pouring. Neither fixes poor venting or a mix that has begun to gel. Slush casting, rotocasting, solid pours, filled systems, and laminated shells serve different forms.
Design casting and cleanup together
Place gates and vents where they fill well and can be repaired. Consider walls, reinforcement, inserts, color, settling, post-cure, paint, and outdoor exposure before choosing resin.
Resin can sensitize skin and lungs. Use ventilation, compatible gloves, eye protection, technical data, and responsible waste handling. Low odor does not mean harmless.