Embroidery stabilizer: which one for each fabric
The stabilizer holds the fabric while the needle works. The wrong one is the most common cause of puckered, crooked or sunken embroidery, even with a good file.
Tear-away
For stable fabrics that do not stretch: twill, denim, canvas, most caps. After stitching, the excess is torn off. On very dense designs, use two layers.
Cut-away
For fabrics that stretch: tee knit, polo pique, fleece, performance fabric. It stays in the garment and supports the embroidery through washes. Without it, the knit stretches in the hoop and the embroidery comes out puckered.
Fusible
One side has glue activated by an iron: it stabilizes thin or slippery fabrics before hooping. Very helpful on rayon and light fabrics.
Water-soluble topping
A film placed on top of towels, plush and velvet: it keeps stitches from sinking into the pile. It washes away afterwards. It is also the base for freestanding lace.
The file matters too
The right stabilizer does not save a file with the wrong density, and vice versa. When you tell the fabric in your order, the digitizing adjusts underlay and pull compensation for it.