Textile warp sizing (Wiki)
Sizing of the warp yarn is essential to reduce breakage of the yarn and thus production stops on the weaving machine. On the weaving machine, the warp yarns are subjected to several types of actions i.e. cyclic strain, flexing, abrasion at various loom parts and inter-yarn friction.
With sizing, the strength — abrasion resistance — of the yarn will improve and the hairiness of yarn will decrease. The degree of improvement of strength depends on adhesion force between fiber and size, size penetration as well as encapsulation of yarn. Different types of water soluble polymers called textile sizing agents/chemicals such as modified starch, polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), acrylates are used to protect the yarn. Also wax is added to reduce the abrasiveness of the warp yarns. The type of yarn material (e.g. cotton, polyester, linen), the thickness of the yarn, type of weaving machinery will determine the sizing recipe.
The sizing liquor is applied on warp yarn with a warp sizing machine.
After the weaving process the fabric is desized (washed).
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The above is consistent w/ both logic, and the inherent softness of ticking material as sold from fabric stores.
In any case, patches are never shot dry. They are either spit-patched, or 7-to-1 patched after wring-out/drying.
Anyone got other real data that says factory washing needs repeating?