Mix ratio

Epoxy cures by chemistry, so an off-ratio mix leaves unreacted resin or hardener behind. That shows up as tacky spots, soft pours, or cloudiness, and it never goes away. Ratios are stated either by weight or by volume. Because resin and hardener have different densities, 2:1 by volume is not 2:1 by weight. Enter your ratio exactly as the data sheet gives it, plus the amount you know, and you'll get both parts in grams and millilitres.

Notes

1. The defaults (resin 1.15, hardener 0.95) are typical values, not your product's. Resin usually falls around 1.1–1.2 and hardener around 0.95–1.05. The real numbers are on the technical data sheet (TDS), under "specific gravity" or "density". The SGs only matter when you convert between weight and volume.
2. Millilitre totals assume the two parts' volumes add exactly. Real mixes shrink very slightly. Mass doesn't change, so weighing on a scale is the more precise method.
3. Scale by weight when you can. Measuring cups hide 2–5% errors in their graduations and in what's left clinging to the cup wall.