The grain line is the direction of the threads in a woven fabricFabric is the outer surface of a puppet — the skin, the cl... More, and in knits the direction the loops run — and it determines how a piece of material behaves once it is cut.
The three directions
Lengthwise grain runs parallel to the selvedge and has almost no give. Crosswise grain runs across the bolt and has slightly more. The bias runs at forty-five degrees to both and stretches noticeably even in a fabric with no elastic in it at all.
Why it matters on a puppet
Puppet pieces are small and heavily curved, so the difference between a piece that eases around a skull and one that fights it is often nothing but the angle it was cut at. Two identical shapes cut on different grains behave like two different fabrics.
Cutting on the bias
is the deliberate use of this. A bias-cut strip will curve around a compound shape smoothly where a straight-grain strip buckles. It is how gullets, cuffs and any binding around a curve get made.
In knits like fleece,
the equivalent concern is stretch direction. Knit fleeceFleece is the knit fabric used as the outer skin on most mod... More gives more across the grain than along it, so the standard is to run the stretch around the head where the circumference is greatest.
Mark it on the pattern
A grain line arrow on every piece is standard practice in garment sewing and it belongs on puppet patterns for exactly the same reason. Along with the napNap is the direction the raised fibres of a fabric lie — p... arrow, it makes cutting a matching exercise rather than a memory test.
The hack: pull a scrap in three directions before you cut anything — lengthwise, crosswise, and diagonally. Four seconds tells you more about how that fabric will behave than any label.