The relining of an oil painting on canvas comes about when the original canvas is frayed, worn or damaged. It is sometimes necessary when the stretcher on which the painting is fixed has decayed or become damaged. The process of relining is essential to bond the old canvas onto a new canvas making sure that as the two canvases are bonded together no air is trapped between the two surfaces. Whilst relining has been established in picture restoration for a long time it is not a task which can be undertaken by unskilled hands.
Relining is sometimes necessary when a picture has been punctured or damaged from the front and before any repainting to the damaged surface can be completed, a stable background needs to be provided to accommodate any filling and new paint.