What do all the codes on an artists' paint tube mean?

Two tubes labelled the same colour from two brands can contain completely different pigments, behave differently, cost different amounts and last different lengths of time. All of that is written on the tube in a standardised form that almost nobody is taught to read. It takes five minutes to learn and it will save you money for the rest of your painting life.

Step by step

1. Find the pigment code.Usually printed small on the tube: a letter for the family and a number. PY is pigment yellow, PR pigment red, PB pigment blue, PG pigment green, PV violet, PBr brown, PBk black, PW white. So PB29 is ultramarine and PB15 is phthalo blue, whatever the brand chooses to call them.
2. Prefer single-pigment paints for mixing.A tube listing one code mixes predictably. A tube listing three is a convenience mix, and mixing it with something else drags in all three, which is a fast route to mud. Convenience mixes are fine to use directly and awkward to mix with.
3. Read the lightfastness rating.Usually a scale — ASTM I and II are excellent and very good; III and below will fade. Some brands use their own star or A-to-C system. For anything you intend to sell, exhibit or keep, restrict yourself to the top two grades.
4. Treat hue as meaning imitation.Cadmium Red Hue is not cadmium red. It is a cheaper, usually less opaque mixture chosen to look similar, often for cost or toxicity reasons. It may be perfectly good paint; it will not behave identically in mixing or in coverage.
5. Check the opacity or transparency symbol.Usually a small square: filled means opaque, half-filled semi-transparent, open means transparent. This matters enormously in watercolour, where transparency is the point, and in oil, where transparent colours are used for glazing.
6. Note the series number and understand what it means.Series 1 to 5 or A to E indicates price band, driven by the cost of the raw pigment. It says nothing about quality — a series 1 ultramarine is not a worse paint than a series 5 cobalt, just a cheaper pigment.
7. Check for staining and granulating notes.In watercolour especially, some pigments stain the paper and cannot be lifted, and some granulate into a beautiful mottled texture. Brands often mark these, and both properties change how you can use the paint.
8. Compare across brands using the code, not the name.If you like a colour and want it cheaper, find its pigment code and look for another brand's single-pigment version of the same code. It will not be identical — binder and pigment load differ — but it will be much closer than matching by name.

Tips

• Student ranges typically use less pigment and more filler, and substitute cheaper pigments behind traditional names. That is why student paint can look chalky and weak when mixed with white — there is less pigment to go round.
• Some historic pigments are genuinely hazardous — cadmiums and cobalt in particular carry warnings. Do not sand, spray or eat them, keep them off skin, and never point a brush with your lips.
• Fugitive pigments are still sold, particularly in cheap sets and in some brilliant pinks and violets. A picture painted in them can visibly fade within a few years in daylight.
• The same pigment code in oil, acrylic and watercolour gives you a consistent colour across media, which is very useful if you work in more than one.

Common mistakes

• Buying by colour name across brands — Names are marketing, not specification. Two tubes called Sap Green can be entirely different pigment mixtures with different lightfastness.
• Ignoring the lightfastness rating on a picture you intend to keep — Fading is invisible until it is not, and it is irreversible. It is the one property you cannot judge by looking at the paint now.
• Mixing several multi-pigment convenience colours together — You can easily end up with five or six pigments in a mixture, which neutralises to grey almost regardless of what you intended.

Questions people ask