A welding process may be configured to convert a substrate comprised of short staple fibers into a welded substrate having significantly increased strength as compared to the raw substrate. When applied to a one-dimensional substrate, such as a yarn, the welding process may also reduce the diameter of the welded substrate compared to that of the raw substrate. Additionally, the welding process may be configured to impart superior color properties to the welded substrate compared to the color properties of the raw substrate, which superior color properties may be very pronounced when performing a welding process on a raw substrate comprised of colored and/or dyed recycled fibers.