En plein air: how a tube revolutionised painting

The Amazing History of Plein Air Painting

Is Watercolour Better in Pans or Tubes? - Jackson's Art Blog

National Gallery - The invention of the paint tube in 1841

En plein air – RDN Arts

Plein Air Painting - A Detailed History of Open Air Painting

Plein Air Techniques For Artists - (for Artists) By Aimee Erickson

Plein Air Painting and Its Influence on Art Creation

En Plein Air - Modern Art Terms and Concepts

Technique Tuesdays: En Plein Air- Principle Gallery

Understanding Impressionism - Artsper Magazine

Plein Air Painting and Its Influence on Art Creation

The History of Plein Air Painting