Mixing guide
Oil tinting strength: why a little blue goes further than a little white
Tinting strength is how far one tube moves a mix per unit of paint. In oil it varies by more than an order of magnitude between pigments, so equal blobs never mean equal influence. A phthalo blue at 4 per cent of the mix can outweigh a white at 86 per cent.
What tinting strength actually measures
Tinting strength comes from how strongly a pigment absorbs light relative to how much it scatters. Phthalos and quinacridones absorb hard and scatter little, so a trace of them dominates. Earths and most whites scatter far more than they absorb, so they move a mix slowly and predictably. This is why the painterly instinct of adding equal amounts fails: you are matching volume when the mix responds to absorption.
Worked example: sky blue in oil
Target #8CB8DC. Chromilla's oil solve returns Titanium White 86 per cent, Ultramarine Blue 10 per cent, Phthalo Blue 4 per cent. It lands at #87BBE6, delta E 1.9, a 95 per cent match. Read those numbers again: the two blues are 14 per cent of the paint by volume and they are doing all of the hue work. Double the phthalo to 8 per cent and the mix goes past the target into a hard cyan. Double the white and almost nothing happens except a small lift in value.
- #87BBE6
Sky blue, oil
- Titanium White86%
- Ultramarine Blue10%
- Phthalo Blue4%
95 per cent match, delta E 1.9 against #8CB8DC.
- Add strong pigments with the tip of the knife, not the flat of it.
- Put the weak pigment down first and bring the strong one to it.
When two strong pigments meet
Target #4A6588, a greyed denim blue. The oil solve returns Titanium White 58 per cent, Alizarin Crimson 21 per cent, Phthalo Blue 21 per cent, at 97 per cent match and delta E 1.4. Here the crimson and the phthalo are both strong, so the ratio between them is nearly one to one and the mix is far more forgiving to small errors than the sky blue above. Strength mismatch, not pigment count, is what makes a mix twitchy.
What Chromilla cannot do here
Chromilla works in percentages of the mix, not grams, and it has no way to know how much paint ends up on your knife. If your palette knife carries a heaped 4 per cent of phthalo, the mix will overshoot and no recipe can prevent that. For strong pigments, mix a small batch first and scale it, rather than trying to hit the ratio in one pass.
Sample mixing ratios
- Sky blue (oil)
- Titanium White 86% + Ultramarine Blue 10% + Phthalo Blue 4%
- Denim blue (oil)
- Titanium White 58% + Alizarin Crimson 21% + Phthalo Blue 21%
Ratios are calibrated as a starting point. Pigment tinting strength varies by brand - use Chromilla's color mixing calculator to recalibrate for your specific tubes.
Try it on your tubes
Open the mixer in oil
Chromilla weights each tube by its measured strength, so the percentages already account for this.
Open Chromilla →Frequently asked questions
- Which oil pigments have the highest tinting strength?
- The phthalos (PB15, PG7) and the quinacridones sit at the top, followed by dioxazine violet. Earths, Naples yellow and most whites sit at the bottom.
- How do I stop a strong pigment taking over a mix?
- Pre-tint it. Mix the strong pigment into white first, at roughly one part to ten, then add that tint to the mix in normal amounts.
- Do the percentages mean volume or weight?
- Chromilla's ratios are proportions of the mix by volume. They are stable when you scale them up, but they assume you measure rather than eyeball the strong tubes.