There are a few reasons you might see spots on your Damascus after etching. Let’s troubleshoot.
- If your Damascus was ground too fast, it may have gotten too hot and the pores in the metal may have closed, which prevents the acid from penetrating correctly. This is most common on thin blades, like kitchen knives, and the best way to prevent it from happening is to take your time and dunk the blade frequently in water while you’re grinding.
- Using anything other than distilled water to dilute ferric chloride often causes spots and problems. Be sure you’re using distilled water, and that it’s less than a year old.
- If your acid has expired, it may not etch correctly. Check the dates on your ferric chloride and muriatic acid.
- If your metal wasn’t clean enough before submerging it in acid, the acid can’t etch it properly. Solvents, mineral spirits, and acetone all leave residue behind, so your best bet for cleaning is to always use alcohol.
- Sanding with too high a grit or polishing the metal before etching will close the pores in the metal and prevent the etch from working correctly. Ideally, you should use 400 to 600 grit sandpaper, and never use a buffer before etching.