Thursday, September 27, 2012

From Old Holland - Pigments


 September 21, 1993


Before starting to write about brushes, canvas, paper, mediums or colours (paints) I start with the hart which is the pig­ment.

By adding different liquids into the same pigment you obtain: watercolour-eggtempera-oilcolour-postercolour or gouache-poly­mercolour-alkydcolour-acryliccolour-soft pastel-oilpastel etc.
The quality of the pigment and the quantity of cheap fillers on one side and the kind of liquid indicates the type of colour mentioned here above. And that colour has more quali­ties as classic, artist, student and schoolquality.

The pigments can easy be divided in two sections:
1. organic pigments: chemical complexes
2. anorganic pigments: elements from earth

The chemical complexes are created during this century and carry names such as: pthaloblue, pthalog­reen, azoyellow, naphtolred, quinacridone-rose etc. These colours you find be labeled under fantasienames as
Old Holland blue, Winsor blue, Grumbacher red, Scheveningen rose, Rembrandt blue, Hortensia blue (LB) etc.

The elements form earth carry names as cadmium, cobalt, iron­oxide, chromium oxide, zinc, lead, manganese etc. Those co­lours carry names as cadmiumyellow, cadmiumred, cobaltblue, cobaltvio­let, cobaltgreen, marscolours, persian-indian-en­glish-venetian reds, chrome-oxidegreen and viridian, zincwhi­te, lead- or Crem­nitzwhite, manganese blue -and violet. If you see a label with one of the above names followed by imitation or hue it is allways a cheaper replacement for the good pig­ment.

After we know now the two basic sections organic and anorganic, the quality of the pigment is next. Pigment-manufacturers can deliver the SAME shade $ 6,00 and also $ 70,00 a pound. Why­??
The difference in price is caused by the next six points:
1. lightfastness (no colourchange in the sun by ultraviolet light)
2. colourpower or tintingstrength (a lot of white with a little bit of colour)
3. brightness (the colour stays clean even mixed with a lot of white)
4. intensity (the deepness of the colour close to the flo­wer)
5. coveringpower (pure cadmium must cover at once even you paint thin)
6. filler which is already in the pigment (decreases the co­lourpo­wer)

Cadmiumpigment can be obtained from the pigmentfactory pure or mixed with bariumsulfate which is a cheap filler like chalk. If this cadmium contains 50% filler the name is cadmium bari­um. This gives no guarantee for the label in your shop. I have tested tubes of cadmium barium which contained more pure cadmium as tubes with the name concentrated cadmium.
How is this possible? The manufacturer used 10% pure cadmium and added the filler by himselves and the truth is "he used concen­trated cadmium". To solve this problem for the artist the most easy way is to compare the different brands cadmium bij mixing into the same white by volume. The deepest is the most powerful. Fillers are bringing all six above mentioned properties DOWN.

In TEACHING LETTER 2 I will explain the different liquids added into the same pigment to get different kind of paints.

Please keep this and the following letters in file,
so you build an extraordinary serie of professional art advices.

Prof. Th. de Beer