How to measure paint mixing ratios in parts
What a part is
A part is any unit of volume you can repeat: a pea-sized blob, a knife-tip, a 1 ml syringe stroke. Parts by volume are what PaintMixLab and most published recipes mean. Weight is more precise but pigments have very different densities, so a gram of Cadmium Red and a gram of Titanium White are not the same volume.
Four ways to measure
- Knife blobs. Squeeze equal-length beads from the tube (a 1 cm bead is a fine unit) and cut them with the palette knife. Good to about ±20%, which is plenty for most mixing.
- Syringe. A 1 ml or 3 ml plastic syringe with the tip cut off draws paint cleanly and gives true volume. Best for recipes you will repeat, and for the white in light mixes where small errors show most.
- Measuring spoons. ¼ teaspoon works for larger quantities (backgrounds, skies). Level them with the knife.
- Scale. A 0.01 g jewellery scale for calibration work. Convert using approximate densities (white ≈ 1.9 g/ml, earths ≈ 1.6, organics ≈ 1.2) if you need volume.
Reading a recipe like 4 : 2 : 1
Put out the largest part first, then add the smaller ones into it. Mix thoroughly — streaky mixes read lighter than they are. Keep a swatch of the result next to the target, in daylight, before you commit. If the value is slightly dark, which is the common case, add white in half-parts and re-check rather than guessing.
When precision matters
Light tints (skies, skin, pale neutrals) — a dab too much of the colour swings them badly. Large areas you will have to re-mix tomorrow. Anything with a strong tinter in it. For a dark, saturated mix you will adjust by eye anyway, so blobs are fine.
Questions
How do I measure paint mixing ratios?
Are paint ratios by weight or volume?
Does PaintMixLab give recipes in parts?
