Variant of SWARF sb.2
With quot. 1596 cf. quot. 1566 s.v. SWARF sb.2
1596. Wills & Inv. N. C. (Surtees, 1860), 259. In dieng stuffe In brasell, half a hundreth and xj poundes, 46s. 8d. In galles, viij poundes, 6s. In swarthe, iiij poundes, 8d.
17834. London Sessions Papers, 472. He told me that there was some swarth, that is iron file dust.
1892. Rigby, in Min. Proc. Inst. Civ. Engin., CXI. 140. A capillary brass tube [in a drilling-machine], supplying soap-and-oil emulsion at a pressure of 80 lbs. on the inch. This washes out the swarth and cools the cutting-edge.