Here at Cornhill Courses it's not only about the upholstery. Our Stage 2 students recently enjoyed a frame repair exercise from Steve. Being able to repair old and/or broken frames is a useful skill and so we thought we'd share the basics of Steve's lesson with you!
1) First of all Steve fully checked the frame; in doing so he noted any weak parts. Then by gently prising apart the joints, and carefully marking all pieces the frame was dismantled.
2) Next Steve explained the importance of scraping away all the old glue, as the strength comes from new glue adhering to wood and old glue and dirt can get in the way of this process. Simply putting new glue into an old joint is like putting new paint onto a flaky old paint surface - the new paint will simply peel off with the old. Steve described the best tools would be a chisel or Stanley blade but to be careful of your hands while scraping!
3) The next step is to replace any broken dowels - these are best to be fluted if possible to allow glues to be spread down the barrel of the dowel hole as well as at the ends of the dowels. Then it is good practice to try a 'dry' run i.e. put all pieces back together without glue in correct order and check everything fits snug.
4) Now take apart again and begin to glue the joints back together one by one. You should use sash clamps here and to take care to protect all show wood with fabric or cork blocks. Ensure that as much glue is squeezed out of each joint as is possible making sure you wipe off all excess glue before it dries. Steve also stressed that It is important not to over tighten the clamps at this point as they are very strong and it is possible to break the frame.
5) At this stage it is important to work quickly as the glues will begin to 'cure' off before the clamps are fitted. If this happens the joint will be weak. Steve suggests that you continue to 'wiggle' the joints as clamps are tightened to ensure that the frame remains square and the pieces can join together solidly. This is better than simply forcing the pieces together with clamps alone.
5) After all joints are attached check the joins one more time and wipe away any excess glue. Ensure that the frame is left sitting on a completely flat surface and is weighted down slightly. This ensures that everything dries square and true. Steve recommends that the frame is kept in this position for around 24 hours to allow the glue to dry fully and to give the joint maximum strength.