Every part of the embroidery process from art preparation to finishing affects the outcome. To help decorators narrow down the embroidery ailments they see in rejected designs, here are some words on how thread can make or break a design. If you understand why flaws appear in your finished pieces, you can isolate and address each probable cause until you’ve either found the culprit or given yourself a solid idea of what went wrong.
Choosing the wrong thickness of thread essentially changes a design's density. If you use 60-weight thread in place of 40-weight in a design, the fact that it is 25 percent thinner means that the filled elements will have 25 percent less density and may lose coverage.
At the same time, if you use 40-weight thread for lettering digitized for a 60-weight thread, you will have densities 25 percent higher than they should be risking gaps and holes in the lettering that won't be large enough to stay open with the additional thickness of the surrounding stitches. Metallic thread, which runs a bit thicker than its reported weight, can cause extra abrasion at high densities, resulting in more fraying and breakage.
Using a vastly different color thread than the design intended can also affect the coverage of the finished piece, while color combinations with very little contrast require less density to achieve the look of full coverage, high contrast combinations like white on black may look less full at the same density settings.