What makes certain inks permanent and others washable? And why does "permanent" ink still dissolve in water.
Certain inks are classified as permanent or washable based on their chemical composition and properties. The main factors that determine the permanence of ink are the solvents used, the type of pigments or dyes present, and the binder or carrier substances that hold the ink together.
Permanent inks typically consist of pigments or dyes that are more resistant to fading or running when exposed to water, light, or chemicals. These inks often use stronger solvents, such as alcohol or acetone, which dissolve the pigments or dyes more effectively and help them bind more permanently to the surface. The binder or carrier substances in permanent inks are also designed to be more durable, preventing the ink from easily washing away or smudging.
On the other hand, washable inks are formulated to be easily dissolved and removed when exposed to water. They generally use weaker solvents, such as water or glycol, which allow the pigments or dyes to disperse and wash away more readily. The binder or carrier substances used in washable inks are less resistant to water, enabling them to be easily cleaned off surfaces.
It is worth noting that even "permanent" ink can dissolve or fade when exposed to certain conditions. While permanent inks are more resistant to water, they may still break down or disperse to some extent when immersed in water for an extended period of time. The specific chemical properties of the ink and the length of exposure to water can affect its stability. Additionally, some types of permanent inks may be partially water-soluble, allowing them to be partially dissolved or spread when in contact with water.
In summary, the permanence or washability of ink is determined by the chemical composition of the pigments, dyes, solvents, and binders used. While "permanent" inks are designed to be more resistant to water and fading, they can still dissolve or fade to varying degrees depending on the ink's specific formulation and exposure conditions.