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Newsletter 05-2016

Kremer Pigmente

Alizarine Madder Lake
 

Alizarine is an organic compound that is historically important as a prominent dye. It is an anthraquinone originally derived from the root of the madder plant. In 1869, it became the first natural pigment to be duplicated synthetically.


Madder was used in ancient Egypt, Greece, and Rome for dyeing textiles and, to some extent, for making pigments. It was said to have been introduced into Italy by the Crusaders. By the 13the century, madder was being cultivated on a fairly large scale in Europe, but there is not evidence of its use in medieval or Renaissance painting. Madder lake was most widely used in the 18th and 19th century, though never as extensively as the ruby-like lakes made from kermes, cochineal, brazilwood, and lac.
 

In 1826 two French chemists, Robiquet and Colin, isolated the coloring principles of madder – alizarin and purpurin – by treating the root with sulfuric acid. The resulting extract, known as garancine, was used to make madder lakes, rose madder and madder carmine. Prior to this improvement, madder lake had been so costly that its use was confined to miniature painting. For fifty years afterward, no other ruby-red or rose-pink coloring matter gave better or more permanent results.
 

Synthetic alizarin was first made in 1868. In the following years, madder lake was superseded by alizarin crimson, a pigment superior to it in every respect. Synthetic alizarin did not replace natural madder immediately. The French government attempted to protect its madder-growing industry by making it mandatory to use madder in dyeing trousers for the army. Since many 19thcentury painters believed that alizarin did not have the delicacy of subtlety of rose madder, the latter continued to be available into the 20th century. Today, most painters prefer alizarin, but a few artists ́ colors made from rose madder can still be found among the European brands. In typical form, rose madder is a very pale pink powder; in oil and watercolor, it seems like alizarin crimson enormously reduced with alumina hydrate. When viewed by transmitted light, paint films of rose madder have a pronounced bluish undertone.

Both the old natural alizarine madder lake as well as the modern alizarine are completely non-toxic.

 


Coloring Concrete

Only very alkaline-stable pigments can be used to color concrete or cement-based mortars.
Please check our suitability list for cement-stable pigments!

Particularly suitable for this application are the iron oxide pigments as well as Manganese Gray (#47510) and Manganese Black (#47501). The amount of pigment depends on the desired color, but more than 4 weight% of pigment should not be added to pure cement. If a mortar is supposed to be colored, that amount may already be too much, because the mortar will also contain aggregates and will not be able to bind as much pigment.

The pigment powder has to be mixed thoroughly with the cement powder. Color pastes can be added to the cement together with the water. For light colors it is preferable to use white cement. Another possibility is to add selected white quartz sand, cristobalite or colored stone powder.

Mind to mix the pigment thoroughly with the pigment, because pigment agglomerates could cause bleeding of the color. Synthetic organic pigments are not suitable for outdoor applications, because they can be washed out in contact with water.

The cement matrix will react different to different pigments:

1. The pigment particle reacts with the cement and stabilizes the matrix: all red, brown and black iron oxide pigments

2. The pigment behaves like a sand particle: most metal oxides, inorganic pigments such as cobalt pigments, nickel-titanium-yellow, titanium dioxide

3. The pigment particle is a foreign body within the cement and will weaken the structure: all synthetic-organic pigments, clay minerals and similarly swellable materials.

The ratio between concrete and pigment depends on the particle size of the pigment. We recommend using the cement particle size distribution curve as a reference, since a certain ratio between cement and aggregate is required for concrete. When a very fine pigment is added, the amount of cement has to be increased. Coarse-grained pigment should rather be regarded like sand.

 

Swedframe® Canvas Frame

Swedframe® Canvas Frames set new quality standards at a professional level. They give stability and angularity and have no warping. The bars themselves distinguish by their unique profile.

The aspen wood is free of knots and has the “FSC” and “Rainforest Alliance” seal.
 

#883381 Canvas Frame Swedframe® 2 x 5 cm

#883382 Canvas Frame Swedframe® 2,5 x 6 cm

#883383 Canvas Frame Swedframe® 3 x 7,5 cm


Prices upon request. We will pleased to submit you an offer.

  

"Fifty Shades of Red"

from 13th May till 2nd July 2016

Galerie Renate Bender
Türkenstraße 11
80333 Munich / Germany

Bender Talk "Fifty Shades of Red

von Azaleenrot bis Zinnober“ mit Dr. Georg Kremer

Vortrag in der Galerie Bender von Dr. Georg Kremer im Kontext zur aktuellen Ausstellung „Fifty Shades of Red“

Thursday, 2nd June 2016 at 7:00 p.m.

Please register at galeriebender@gmx.de

or by phone +49 (0)89-307 281 07!


Special offer: Sico-Pigments

#99415 Sicoplast blue

PB 15, very lightfast

#99416 Sicomix purple

PB 23, very lightfast

#99417 Sico red PRL

quite ligthfast

#99418 Sico yellow HR

quite ligthfast