What does 'lining' a painting mean?

Lining is a major treatment in paintings conservation, and should only be used when absolutely necessary

Contour Line - Mrs. Cook's Art Class

Line Drawing: A Guide for Art Students

Our Guide To Jacket Linings - Fabric Types, Half vs Full Linings

What does 'lining' a painting mean?

Line in Art - Discover the Different Types of Line in Art

Conserving Canvas Project - The Courtauld

The Truth About How Fine-Line Tattoos Heal — See Photos

What does 'lining' a painting mean?

Oil Painting Lining Process

5 Types of Line in Art, Their Meaning And When To Use Them

Line in Art - Discover the Different Types of Line in Art

Silver lining (idiom) - Wikipedia

Liven Up Your Line Art With Smooth, Attractive Lines

Lining paintings, when does one start in conservation and

What Is an Implied Line in Drawing?