Over time paintings suffer exposure to many dangers, such as clumsy handling, heat exposure and high humidity, creating tears, shrinkage and deterioration of the canvas backing. Relining a painting with new canvas glued to the back provides a strong and mould-free structure to support the paint, repairs tears and extends the life of the painting.
Mix equal amounts of white flour and cold water to create a paste. Brush the paste on to the front of the paint. Cover with Japanese tissue paper. Allow to dry. Apply paste over the tissue paper. Cover with gauze. Allow to dry. Cover the gauze with paste. Lay a sheet of heavyweight archival paper on top. Allow to dry. Glue two more layers of archival paper on top. Allow each layer to dry before applying the next.
Lay the painting flat, facedown on a cloth-covered table. Vacuum the back and frame carefully. Pry the nails or staples holding the canvas in place loose with the pliers to release the canvas from the frame. Mark the bars as "left," "right," "top" and "bottom" in pencil in order to attach the relined painting later in the original position.
Dip a clean cotton ball in mould remover. Lightly rub away any foxing (brown spots of ferrous oxide-caused mildew) from the back. Wipe away the mould remover with distilled water and a clean sponge. Allow to dry. Sand the back of the canvas carefully to thin without disturbing the paint on the front.
Dissolve 1/8 cup dammar resin over heat. Add 1/8 cup beeswax to the resin and continue to heat until melted. Remove from heat, add three scant drops of English turpentine and stir. Cool to 76.7 degrees Celsius then apply the mixture to the back of the painting. Cover with the second piece of canvas and dry-iron to adhere and flatten, working from the centre out to the corners. Allow to cool. Flip the canvas face up. Spray distilled water on the top layer of paper then peel away. Continue to spray and peel or wash away the layers of paper and gauze until clean.
Re-stretch the painting. Place the painting facedown on a clean table. Lay the stretcher bars over the back in the original position; adjust the bars to line up with the edges of the paint. Fold the canvas of a short side over the corresponding stretcher bar. Staple the canvas in place at the centre of the bar. Pull the canvas of the opposite side tight over the stretcher bar with the canvas pliers; staple at the centre. Staple the two long sides of the painting to the stretcher bars in the same manner. Continue to staple, working on opposing sides and moving from the centres out to the corners until complete. Fold over the extra canvas at the corners and staple in place. (See Reference 3)
Do not use this method on paintings with a high impasto, or texture; the heat and pressure combined can flatten the built-up paint and destroy the original image. Use synthetic wax binders that attach without heat instead.