💎 Epoxy Resin Calculator

Temperature is everything—work in 75-85°F environment. Cold resin is thick, traps bubbles, and can fail to cure properly. Hot resin (over 90°F) cures too fast, yellows, and can crack from exothermic heat. I keep my workspace at 77°F year-round with a space heater in winter and AC in summer. When I started, I poured in my 60°F basement and battled endless bubbles and slow cures. Moved to a temperature-controlled room and my success rate jumped from 70% to 98%. If your resin bottles are cold, warm them in 100-110°F water for 10-15 minutes before mixing.

Mix by weight, not volume, for ratios other than 1:1. A 2:1 ratio "by volume" seems straightforward, but resin and hardener have different densities. Pour 100ml resin + 50ml hardener looks right, but might be off when weighed. I ruined a $200 river table pour because I mixed a 2:1 resin by volume when it needed weight-based mixing. The piece never fully cured and stayed tacky in spots. Now I use a scale for ANY non-1:1 ratio—zero the cup, add resin, note weight, calculate hardener weight, add exact amount. Professional brands specify "by weight" vs "by volume" clearly; cheap Amazon resins often don't, so test small batches first.

Stir for 3-5 minutes minimum, scraping sides and bottom constantly. Under-mixing is the number one cause of uncured spots. Set a timer and actually mix for the full duration, not "I think it's mixed." Scrape the cup sides where unmixed material hides. Then do the "two-cup method"—pour into a clean cup and mix another 30 seconds. This catches any unmixed resin clinging to the original cup. I learned this after six failed pours with tacky sections. Turns out I was mixing for maybe 90 seconds and calling it done. Started timing myself at 4 minutes with constant scraping, and cure failures dropped to near-zero.

Don't exceed maximum pour depth or your piece will crack from heat. Epoxy generates heat as it cures (exothermic reaction). Pour 2 inches of fast-cure resin in one go and you might hit 200°F+, causing cracks, yellowing, or warping. For thick projects, use deep-pour resin (slower cure, less heat) or layer thin pours. I poured 3 inches of art resin into a mold once, heard cracking 6 hours later, and found a massive spider-web fracture from the heat buildup. That blank cost $85 in materials. Now I follow the manufacturer's max depth religiously—1/4\" for regular art resin, 2\" for deep-pour formulas.

Account for 10-15% waste EVERY TIME—you'll thank yourself. Resin clings to mixing cups, stir sticks, and pouring edges. You always lose some to spillage. Calculate for exactly the mold volume and you'll run short 80% of the time, leaving you with a half-filled mold and no mixed resin to top it off. I've learned to mix 15% extra religiously. Sometimes I have leftover—great, I pour it into a small silicone mold for bonus pieces. Better to have 2oz extra than to be 0.5oz short and ruin a $40 project. This single habit solved my most frustrating resin problem.