What makes certain inks permanent and others washable? And why does "permanent" ink still dissolve in alcohol?
Certain inks are classified as permanent or washable based on their chemical composition. The main difference lies in the types of ingredients used. Here is an explanation of what makes these inks different:
Permanent Ink:
Permanent inks are typically made of pigments suspended in a solvent-based solution. They contain dyes or pigments that are resistant to fading, water, and other solvents, making them more resistant to fading and smudging over time. These inks usually adhere strongly to paper and other surfaces, making it difficult to wash or remove them. They are commonly used for writing or printing documents that require long-term durability, such as signatures or official records.
Washable Ink:
On the other hand, washable inks are designed to be easily removed or washed out. They are usually water-based, meaning that the primary solvent in the ink is water. This composition allows the ink to dissolve when it comes into contact with water, enabling it to be washed off easily from most surfaces. Washable inks are commonly used in markers, children's art supplies, and other applications where easy removal is desired.
Regarding the second part of your question, it is important to note that the term "permanent" is relative. While permanent inks may be highly resistant to water or other everyday solvents, they can still be soluble in certain strong solvents, such as alcohol. This is because alcohol is a more powerful solvent than water and can break down the chemical bonds within the ink, dissolving it to some extent. However, even though permanent ink may dissolve in alcohol, it still maintains its durability and resistance to fading when exposed to water, light, or other ordinary solvents.
So, in summary, certain inks are labeled as permanent or washable based on their chemical composition, pigments used, and solvent types. Permanent inks are more resistant to fading and more difficult to remove, while washable inks are designed to be easily washed out. While permanent ink may dissolve in alcohol, it still maintains its permanence in everyday situations.