A fabric cornice board using a wood base is very easy to make. The wood, either hardboard or plywood, provides a firm support for the interlining and fabric.
My own preference is to use hardboard for a fabric cornice board. It's not too heavy, is easy to join sections for larger cornices, and the returns are simple to make. We'll be using hardboard as an example in this section.
Plywood is also used, and for a really secure base - especially if you need to attach components to it by screwing into it - is a good alternative. For some situations ¼" plywood can be use, but it does need to have a very strong and firmly fixed mounting board. Make the width of the wood ¼" (0.6cms) wider. This will allow for the thickness of the fabrics when the returns are bent around the mounting board.
Take hardboard as an example. The standard size is 8'0" by 4'0" (2.42m by 1.21m). If your cornice is 12'0" (3.65m) wide, then you'll need to join two pieces.
Cut your two pieces to the correct size, for example, one of 8'0" and the other 4'0". If you're going to have a shaped cornice, make sure the depth is enough for the longest section(s).
Bring the two sections together. I suggest you put the natural edges together because they should be very straight. Cut two lengths of fabric about 6" (15cms) wide and almost as long as the depth of the wood. It's best to use a tightly woven fabric for this.
Apply adhesive to the area and stick the fabric to this side. Latex based adhesives work fine for this, or any adhesive which works well with fabric. You can also buy very good ones in spray cans.
When the adhesive has dried, turn the cornice over and repeat on the other side. This forms a surprisingly rigid join.
The returns are attached in exactly the same way, except you only stick the fabric on the back so it forms a hinge.
If you're having a shaped cornice, draw the shape on paper or card, and mark it on the wood. Cut out the shape with a jigsaw.
Unroll enough interlining to cover your fabric cornice board, allowing about 2" (5cms) extra for turnings. If your cornice is wider than the width of the interlining, use a lengthwise piece. If you can't manage this (not enough interlining?) it won't matter if you just place widths together. Don't sew them together or overlap them because the double thickness will show.
Place the interlining as flat as possible on the table, and place the cornice centrally with the front resting on the interlining. Pull the interlining so it's completely flat.
Now trim the turnings as shown in the illustration. The corners will need to be trimmed, and any curved sections as shown.
Then apply adhesive around the edges and stick the interlining to the wood.
When the adhesive has dried place the cornice front side up on the table. If you haven't already done so, join up the fabric widths you'll need.
Place the fabric on the cornice, making sure the middle width is central (unless you are ignoring widths and using the pattern). Pin the fabric in position using strong pins pushed into the edge of the wood. A thimble or small hammer is useful here.
Don't pull the fabric too tight, just enough so it's flat. This is especially necessary on the width, because when you turn back the returns there may be a slight pulling effect.
Look out for joins which are skewed, horizontal lines not staying horizontal, and patterns not correctly placed. When you're happy with the positioning, turn the cornice over.
To fix the fabric do exactly the same as for the interlining. But this time take extra care on corners and cut outs. Once the adhesive begins to hold you can remove the pins.
When the adhesive has dried, if you want to have a cord on the bottom, this is the time to sew it in position.
Turn about 1" (2.5cms) under all round the cornice and pin it in place, making cuts into the turnings so it follows any curves. The lining should be sewn using a slip stitch almost on the edges as shown.
Now you can either sew or stick on any accessories to the fabric cornice board such as trims, fringes and borders.
This way of making a cornice board will give great results. You can't beat the tailored look of an upholstered finish.