Y broses o wneud dur di-staen pibell di-dor: 1, gwneud dur → 2, rholio dur crwn → 3, perforation (anelio) → 4, tynnu oer → 5, rholio oer (anelio, demagnetization, piclo, glanhau) → 6, sgleinio wal → 7, sgleinio wal allanol → 8, pwysedd aer ...
Darllen mwy