All paintings on canvas should have backing boards as a preventive conservation measure. Installing a backing board on a stretcher will:
- protect the painting from damage from behind;
- prevent dirt and debris from falling between the stretcher bar and the canvas;
- buffer fluctuations in relative humidity (RH) by enclosing the backside of the painting;
- reduce vibration of the canvas in transit; and
- decrease the painting’s sensitivity to shock.
To properly serve as protection, the backing board must be strong and rigid, and it must be sealed on the reverse of the support to reduce air circulation. It should have low permeability to moisture and be capable of absorbing and releasing moisture. It should also be lightweight. Artefex Canvas Backing Board provides all of these properties in one easy to install kit.
Figure 1. Installation of Artefex Backing Board to stretcher bars on the reverse of the canvas (left). Two backing boards attached to reverse of stretchers and between a cross bar (right).
Included with the Artefex Backing Board
Artefex Backing Board includes everything needed to protect your paintings on canvas. In the kit are a:
- plastic board;
- pH-buffered matboard;
- foam stripping;
- stainless steel cup washers; and
- zinc-plated screws.
Backing Board is lightweight, rigid, and allows minimal moisture diffusion. The backing board consist of two pieces: The plastic board seals against short-term environmental changes (e.g., daily environmental cycles). The matboard provides additional control of the relative humidity (RH) within the space enclosed by the canvas and the backing board. This layer releases moisture as required in response to environmental conditions, thereby helping to prevent the low RH conditions that are detrimental to the paint, ground, and size layers of the painting.
Foam Stripping seals the space between the backing board and the stretcher, reducing air leakage and creating a beneficial micro-environment between the canvas back and the backing board. Ordinary weather stripping material may deteriorate and emit volatile products harmful to the materials in paintings. The foam stripping included in this kit is composed of chemically stable material that will not deteriorate and lose its sealing ability.
To assemle the backing board on the reverse of your canvas painting, you will need the following tools:
- Screwdriver, Phillips head, #6;
- Awl or other small pointed tool for piercing holes;
- Pencil or marker; and
- Ruler or measuring tape.
Figure 2. Adhere the foam stripping to the backing board to form a seal between the backing board and the stretcher.
Figure 3. Plastic board and matboard are attached to the stretcher with wood screws and cup washers.