How do I do a big jigsaw puzzle efficiently?

A large jigsaw is not one problem with a thousand parts; it is a sorting problem followed by many small assembly problems. People who find big puzzles overwhelming are usually working from an unsorted pile, where every piece has to be compared against every space.

What you'll need

• A surface you can leave undisturbed, or a puzzle board or roll-up mat
• Shallow trays, baking sheets or box lids for sorting
• Good, even light
• Puzzle glue and a backing board, if you intend to keep it (optional)

Step by step

1. Set up somewhere you can leave it.A large puzzle takes days. A dedicated board, a roll-up mat or a sheet of hardboard means it can be moved off the table for meals, which is what determines whether a puzzle gets finished.
2. Sort rather than tip.Turn pieces face up in batches into shallow trays as you go, rather than emptying the box onto the table. A single unsorted pile is the reason large puzzles feel impossible.
3. Separate the edges first.Every piece with a flat side goes in its own tray. It is the one unambiguous category, it takes minutes, and it gives you an immediate structure to build against.
4. Sort the rest by colour and pattern.One tray per distinct region of the image — sky, water, a red building, text, foliage. The categories come from the picture on the box, so keep the box lid propped up where everyone can see it.
5. Add a shape sort for uniform areas.For a large area of one colour, sort by piece shape instead: two-in-two-out, three-out-one-in, and so on. Standard cut puzzles have a small number of shapes and this converts an impossible colour problem into a manageable shape problem.
6. Build the border.It defines the working area and gives everything else a reference. On some modern puzzles the border is genuinely hard because the edge pieces are similar, so it is not always fastest, but it is always useful.
7. Work distinctive regions before uniform ones.Text, faces, sharp colour boundaries and any object with a clear outline. Each completed region shrinks the remaining problem and gives more edges to work against.
8. Work uniform areas by shape and by position.Large expanses of sky or sea come last, and are solved by shape matching and by working outwards from what is already assembled rather than by looking at the picture.
9. Store a part-finished puzzle properly.A purpose-made puzzle board with a cover, a roll-up mat, or a large sheet of card slid underneath and covered with a second sheet. Assembled sections survive careful moving surprisingly well if the board underneath is rigid.
10. Glue and frame it if you want to keep it.Slide a sheet of card or greaseproof underneath first. Apply puzzle glue with a spreader across the surface, working it into the joins, and let it dry completely flat. Glue the back too for a piece that will be hung, then mount on foam board and frame.

Tips

• Light matters more than people expect. Even, bright, shadowless light shows subtle colour differences that decide most matches, and a lamp at a low angle also reveals piece shape.
• Puzzles with a matt finish are far easier than glossy ones under artificial light, because gloss reflects and hides the image.
• Working with someone else is faster if you each take a region rather than both working the same area.

Common mistakes

• Tipping the whole box out at once — It creates a single pile in which every piece must be compared against every gap. The sorting was going to happen anyway; doing it up front makes everything after it fast.
• Working without the box picture visible — The image is the map. Propping the lid up where everyone can see it is the difference between searching and looking something up.
• Forcing a piece that nearly fits — It damages both pieces, and worse, it creates a false anchor that makes everything around it wrong. If it needs pressure, it is not the piece.
• Gluing a puzzle on the table it was built on — Glue runs through the joins and sticks it down. Slide card or greaseproof paper underneath first, always.

If it doesn't work

Questions people ask