Some artists claim that tube paints have a more vibrant color than pan paints, but I have not found that to be true - even when I measure the color difference digitally. I suspect difference may simply be due to the fact that it is easier to achieve a high concentration of paint and water with tube paints. Indeed, some artists use the paint straight from the tube.

The disadvantages are that it's hard to judge exactly how much paint you need for any painting, so you usually end up with excess paint on your palette, which dries out anyway. And once tube paints are contaminated with other colors (particularly one of the phthalos), they are difficult to retrieve.

Tubes are not a perfect packaging solution. Pigment and vehicle separate if the tube is infrequently used or has spent a long time hanging in the retailer's paint rack. The cap sticks if it is gummed up with paint. The tube can burst or the paint can dry out from prolonged exposure to heat or improper sealing. And tubes are bulky — they contain mostly water and gum arabic, and only 5% to 50% actual pigment.

Dry pan colors have different advantages. They are quick to set up and paint with — just open your paint box and wet the cake - and very easy to clean up. If protected from moisture and extreme temperatures, they will store indefinitely. There is no wasted color, other than what you lose in your rinsing tubs or leave in your mixing areas. They are easy to clean if you pollute them with another color (villain phthalo again). And they are marvellously compact and easy to transport.

The disadvantages of pan colors are that they require more fussing to moisten and mix up.* They yield small quantities of color at first (though more when thoroughly moistened). Some pigments (such as earth pigments, viridian or rose madder genuine) form hard cakes that are more difficult to work with, and sometimes produce streaky color mixtures. The frequent rubbing of the cake required to moisten it or pick up paint can be hard on brushes, especially with the abrasive cobalt pigments. And pans are expensive for the amount of pigment they contain - anywhere from three to five times the cost of tube paints.

Don't make the mistake of thinking that tube paints are for "real" artists and pans are for students or children. David Cox, Winslow Homer, J.S. Sargent, John Marin, Edward Hopper and Philip Pearlstein, to name a few, are among the many artists who preferred pan colors to tube paints, even in the studio. 

By Bruce MacEvoy      www.handprint.com

* White Nights pan watercolours are produced by a different method than dry extrusion. They are much softer than dry cakes and can be easily pick up with a damp brush without any pre-wetting.

Watercolours

...Any pan watercolours are in 3-5 times more concentrated than tube ones. The White Nights Artists full pan (2.5 ml) is equal in a pigment load to about 8.5 ml tube of an artists' grade.

... The White Nights Artists' pan paints can be lifted very easily with a damp brush without pre-wetting as they aren't ordinary dry cakes in plastic pans but rather softer pan watercolours.

Oils

...MasterClass Artists' Oils are restoration oils and used to restore old paintings from the State Hermitage museum (St.Petersburg), the State Tretyakov gallery (Moscow) and many others.

...About 30% of MasterClass Artists' paints (18 out of 64) are very lightfast and permanent  Natural Earths.

... Among MasterClass Artists' Oils  there are two unique green Natural Earth paints - transparent Volkonskoite and Glaukonite paints.

...Oil paint has a higher pigment load because it is able to absorb substantially more pigment than acrylic because linseed oil has a smaller molecule than does acrylic binder.

Pigments and the size of the pigment particles

Spectrum colours: infrared->red ->orange->yellow->green<-blue<-dark blue<-violet->ultraviolet

Particle size: bigger -> smaller <-bigger

...The grinding of pigments can lead to the colour shift towards the centre of the visible spectrum (green colour). For example, a pigment may change its colour from red to orange or from blue to green. Sometimes, this is the way to get two different coloured paints out of the same pigment.

...But sometimes, an original lively colour of a pigment can become dull and uninteresting if overground. It happens with lapis lazuli (natural ultramarine) when it loses its brilliant dark blue colour and becomes pale greenish blue.

... Colour would be more pure and intense if a pigment had uniform particles of about the same optimal size.

Pigments vs Dyes

...Pigments are colorants that are insoluble in water and most other solvents used as vehicles and binders (water, gum arabic, linseed oil, acrylic polymer, etc.). Actually, pigments must not be soluble in water at all. Otherwise, they cannot be called  'pigments' but rather 'dyes'.

Vladimir Zhikhartsev  is a plein air watercolour artist who lives and works as a painter, ice sculptor and art tutor in Alaska, USA.                    www.vladimirzhikhartsev.com