How can lithopone be distinguished from other white pigments?
If lithopone is poured with dilute hydrochloric acid, hydrogen sulfide will be formed.
How can you distinguish heavy spar and barite white from other white pigments?
Heavy spar (baryt) and artificially produced barite white are insoluble in all bases and acids.
How can the special anti-corrosion protection capabilities of mini-lead can be explained?
Lead minium forms with fatty acids oil-containing binders very water-repellent lead soaps. This reduces the swelling of binders containing oil under the influence of water.
Because red lead is alkaline, it can passivate acidic agents, conducive to corrosion. This passivation is done independently of any binders.
Please provide active, anticorrosive effect of zinc dust pigments
If in the shell is by weight at least 92-95% zinc dust, it is in contact with an electrolytic solution that a galvanic cell is formed. As a result of electrochemical reactions, the pigment with zinc dust erodes and thus protects the steel substrate.
Please present the possible modes of action of active pigments, giving relevant examples
Active pigments can interact in very different ways:
1. Pigmenty zasadowe mogą tworzyć z kwasami tłuszczowymi spoiw olejnych bardzo wodoodporne mydła. As a result, the water swelling of the oil binders is also reduced. An example here may be, first of all, lead minima and lead white.
2. Pigmenty zasadowe, np. mini lead, can passivate acidic products, conducive to corrosion.
3. Wskutek galwanicznej różnicy potencjałów cynku i stali następują procesy elektrochemiczne powodujące erozję cynku, and protect the steel from rusting. Zinc dust pigments can provide such cathodic corrosion protection, however, the content of zinc dust in the painting material must be min. 92-95%.
4. Niektóre pigmenty, np. calcite and quartz, they can form silicates with water glass and thus act as active pigments. These pigments and fillers are used in silicate paints as silicification-promoting additives.
What special properties do tar pigments have in comparison with mineral ones?
Tar pigments are more resistant to acids and alkalis. Simultaneously, tar pigments show a greater coloring capacity, but they cover worse and usually have lower resistance to high temperature.