Two Answers kirby.
First, tell your students the differences are the same as compared to that of Earth and Pluto.
That should result in a rousing round of laughter and good cheer between you and your students.
Secondly, tell them this:
Paints and inks are similar in 3 respects.
1) They both need a vehicle to be a carrier to their destined location. With paint it is usually a wall, a car body or any large inanimate object. With ink the destination is usually a designated substrate that travels mechanically in form, rather than paint that is carried normally by an animate object, a human.
2) Both paint and ink contain colorant, best known as pigment. Paints contain much lesser amounts of pigments versus inks, not because what many would think. For instance, indoor paint for a room in a house is usually a pastel, light tint shade. But that's not the reason for lesser percentage of pigment. The reason is the film thickness of paint versus ink. Paint film applied by a boars head brush is a minimum of 5-10X thicker than an ink film applied by a print press. Hence, the difference in pigment differences, paint vs. ink. An average paint contains less 1-2% dry colorant pigment. An average litho ink contains 12-15% dry colorant pigment. Now you can see.
3) Drying mechanisms, paint versus ink. Most paints today are latex based and rely on quick oxidation by rapid introduction to ambient air. Now I know thee are oil based paints, and yes, these come closer in nature to the drying and setting to an offset oxidative ink. It is oleoresinous based, That is the drying oil, or vegetable oil, in the ink reacts with the salt type driers that are also part of the formulation. These oils are much slower drying and setting versus paint types, but again remember, 'thinner films'. Why no latex inks? Because the latex does not have near the hardness to hold up to the rigors of most printed material produced. If so, once touched, the latex ink film would peel off and you'd be left with a white sheet.
Kirby,
I hope that explains the differences in basic form between paints and inks. And one more thing....Thank you in providing education to our young people who will be our next generation to live and inhabit our world.
D Ink Man