Pete Bingham explores the potential of foam board

As we discussed in a previous issue of In The Frame, box mounts can be a particularly painful thorn in the side for most framers but, now, with the use and availability of foam board becoming wider, all or most of these problems have all but ceased to exist. In the last article we covered the making of a straight-sided box; this time I thought it would be logical to have a look at how to go about making one with 45° sloping sides. There are a couple of formulae involved here, the first of which is how to establish the actual size of board you need before cutting the blank to size. To do this, proceed as follows:

Draw a horizontal line on a piece of paper. From this draw a line vertically up from it at 90° to the horizontal. Make a mark up the vertical line at the depth you want the finished box to be. Then, along the horizontal line, from the base of the vertical, make a mark at the same distance. Join the two marks together and this will give you the actual measurement that you need to add to the base area required for the box. Add all these together and you have the cutting size for the blank. Now take a piece of foam board and an appropriate piece of the mountboard that you want to use to line the box. I'm using linen mount board and 3.5mm foam board. Apply PVA adhesive to the foam board and stick the mount board to it. Give it a gentle squeeze in your dry mounting press to make sure it's stuck properly. Cut the resulting sandwich to the required size. Place this in your mount-cutter face up and extend the blade so that it will cut through the sandwich of mount and foam board. Cut a bevel on all four sides of the blank. This will allow the box to have a flat surface to the top edge when folded to shape. Turn the blank over, placing it face down and mark the depth of the sides all the way round. I'm using a depth of 11/2". At each corner, mark 1/2" in along each side. This allows the corners to meet at 45° when folded. Cut through the sandwich from where the lines meet to the points on the edge and remove the arrow shaped pieces. Using a scalpel or other sharp knife, cut through the foam board and into, but not through, the mountboard. This helps the board to fold sharply and neatly (try it on a scrap replica to get the feel first). Fold each side so that the corners meet. Overlap each corner with its neighbour by half the thickness of the board and fix it in place with a length of tape, pulling the tape tight around the corner. Ease each corner back so that the corners meet snugly. Cut a mount with an aperture that is about 2mm less than the inside of the top of the box. Place this face down and apply double-sided tape to the underside of the bevel, working as close to the edge of the bevel as possible. With the box face up, place the mount on to the box and fix it in place. This will hold the mount in place temporarily whilst the reinforcement is added. Cut four strips of foam board of appropriate width with a bevel on one side. With the box face down, apply these strips to the underneath of the mount so that the bevelled edges bear against the sloping sides of the box, thus holding the box in position more permanently. For extra rigidity, fill the corners of the folds in the box with PVA wood glue and allow to dry completely. Tape up neatly and the finished unit is ready to go in the frame! The feedback we receive from professional framers after every issue of In The Frame gives us a very good idea of what is popular editorial. Pete Bingham's contribution to each issue is often the subject of favourable comment. We are delighted to say that Pete has agreed to continue experimenting with our products to develop ideas to help you get the most from the range and to enjoy yourselves in the process. If you have any ideas of topics you would like Pete to explore in future issues, please contact us on the Colourmount Hotline or write to the Editor at Slater Harrison. We can't guarantee that we'll be able to ask Pete to develop ideas for all your suggestions, as space in In The Frame is limited, but we will cover as many topics as we can in future issues.