2. How to Adjust a Wood Keyed Stretcher Using Wooden (wedges) Keys and Why. The John Annesley Company home

3. Why? Loose canvas –All fabric expands and contracts due to hot and cold temperatures. During the course of the day, as the temperature fluctuates, and the fabric expands and contracts. The wood is also expanding and contracting with the ambient moisture in the atmosphere. The force of gravity is pulling constantly. The combination of these forces will cause the fabric to fatigue. This occurs primarily along the edge of the canvas where the canvas and the stretcher make contact. To remedy this problem, you have three options: –You can re-stretch the canvas, which is the best option. –You can expand the stretcher bar, there by tightening the fabric. A wood keyed stretcher allows for independent expansion in either direction in each corner. –You can shrink the fabric, making it tighter, by using moisture (water). Each time this method is used, you reduce the elasticity of the fabric. home

4. Tools and Materials Needed Awl Small Hammer Side Cutters Wooden Keys home

5. N1 Stretcher (face view) home

6. N1 Stretcher (back view) The back side has the stapled corners. home

7. Corner Detail Showing Staples home

8. Getting Started Pry the staples using an awl. home

9. Once the staples have been lifted from the stretcher, finish pulling them out with a pair of side cutters. home

10. Staples Removed home

11. Corner Detail with Two Wooden Keys home

12. Detailed Mortise View home

13. First Wooden Key Inserted Insert first key into bottom slot, flat side slides along the inside edge of the stretcher, and into the mortise. home

14. Second Wooden Key Inserted Insert second wooden key into top slot, flat side slides along the inside edge of the stretcher, and into the mortise. home

15. Making Adjustments Gently tapping this key will cause the joint to move in the direction of the arrow. home

16. Making Adjustments Gently tapping this key will cause the joint to move in the direction of the arrow. home

17. Detail of Joint Spacing home

18. Overview of Wood Keyed Stretchers Advantages –Easily assembled and disassembled using minimal hand tools. –The corner joints (open mitered, double mortise and tenon) can be expanded independently in each direction. –Braces can also be keyed with mortise and tenon joints. home Disadvantages –Damage can occur to the painting by striking the canvas accidentally with the hammer while hammering the keys. –Keys can break, and become lost between the canvas and the stretcher, causing damage to the painting. –Keys can become lost.