There are guidelines regarding needle size, thread size, paper weight. Not rules, mind you, guidelines. I decided to collect them here for quick reference.
Thread: the first number represents the thickness: the higher the number, the lighter the threads. The second number represents the ply, the number of strands plied together. “Polished” thread has a small amount of wax applied during spinning, which is less gunky than pre-waxed threads, stronger than unwaxed and has a nice sheen. Usually sold in grams, so yardage varies by weight/ply.
Needles: Generic bookbinder’s needles will accommodate most unwaxed threads. The larger the needle size, the smaller the needle. A large eye is important for threading linen thread, but a smaller diameter will leave a smaller hole – important for exposed sewing work. Judge the gauge of the eye opening: the larger the gauge, the finer the eye.
Bookbinder’s needles are hard to come by. A #1 bookbinder needle (#1BB) is 2 3/8″ long, 19 gauge with a blunt tip, .042″ in diameter. A #18 bookbinder needle is 2-1/2″ long, 18.5 gauge, .046″ in diameter. Bookbinders needles have a rounder eye which is polished to reduce wear on the sewing thread. Most needles used by bookbinders are classified as Darners in standard sewing work and is what the chart below is based on.
Curved needles are for Coptic stitching and will accommodate most threads. They come in #5 – 1.25″ diameter, #6 – 1.50″ diameter, #7 – 1.75″ diameter. Size is dependent on ability and distance between sewing stations.
Awl needles are typically 17 gauge and used for punching sewing stations in signatures.
| Thread Weight/Ply | Needle Size | Paper Weight | Binding Type |
| Hair Silk/2 | #1BB, #12 (Beading) | N/A | Textile Repair |
| Hair Silk/4 | #1BB, #12 (Beading) | N/A | Textile Repair |
| 150/3 | #5, #18BB | ||
| 60/3 | #5 | ||
| 40/3 | #5 | ||
| 35/3 (@ 0.38mm thick) | #5 | Large textblocks | |
| 30/3 (@ 0.42 mm thick) | #3, #5 | Large textblocks | |
| 25/3 (@ 0.50 mm thick) | #3 | Most hand binding | |
| 20/3 | #3 | Most hand binding | |
| 18/3 (@ 0.55 mm thick) | #1, #3 | Most hand binding | |
| 18/4 | #1 | Exposed sewing | |
| 15/3 | #1 | Exposed sewing | |
| 14/3 | #1 | Exposed sewing | |
| 12/3 | #1 | Exposed sewing | |
| 10/3 (@ 0.72 mm thick) | #1 | Exposed sewing | |