Acrylic on Paper Paintings
These tend to be about 220 x 220 mm (9 x 9").
Acrylic paintings have gained in popularity – rightly so – where once thought to be 'not as good' as oil. I think this is simply because acrylic, made with an acrylic polymer holding the pigment together, is a relatively modern painting medium, invented in the 1940s and commercially available in the 50s, according to Wikipedia. It's a fast drying and durable artists medium. I find the fast drying a challenge, but also useful when needing to work on a painting continuously. Acrylic is mixed with water instead of oil and this can be an advantage, because it makes mixing colours and cleaning-up a simpler exercise. However, there are not as many pigments available in Acrylic and acrylic tends to darker ever-so slightly as it dries – I have noticed this, though it is ever-so slight.
Acrylic lends itself to mixed media work, where other media do not. Almost anything can be mixed in with it because of the synthetic binder.
You could argue oils take more skill, though this is only from the point of view that with acrylics, an artist can build a painting up in whatever way they want to, without creating a painting that in years to come will crack.
As I've said, I find acrylics have their place when a specific way of painting is needed. I'll often use them for experimenting with ideas or ways of painting, before then using oil paints for a finished landscape.