(NH₄)₂S₂O₈
Ammonium Persulfate
Material Specific
Composition
Ammonium persulfate 15–25%
PACE product, by weight
Method
Immersion or swab
Time
30–60 s
Alternative Names
Tags
Reveals
Grain boundaries; annealing twins; alpha–beta phases in brass
Typical Results
PACE 15–25% ammonium persulfate solution for copper alloys. Milder than NH4OH + H2O2 with a longer shelf life. Reveals grain boundaries and annealing twins in OFHC copper, brass, nickel-silver, and bronze. Same chemistry as Copper No. 1 only if positioned identically. PACE Copper No. 1 is actually dilute HNO3 (different chemistry).
Application Method
Method:Immersion or swab
Typical Time:30–60 s
Preparation Notes
PACE Ammonium Persulfate is supplied ready-to-use. Composition (by weight):
| Ingredient | CAS No. | % | Hazardous |
|---|---|---|---|
| Ammonium persulfate | 7727-54-0 | 15–25% | Yes |
| Water | 7732-18-5 | 75–85% | No |
Application Notes
Immerse or swab 30–60 s at room temperature. Rinse with water then ethanol; passivate with Cu-Pass-Sol if standing time before imaging.
Troubleshooting
Sluggish attack: solution has aged; replace bottle. Tarnish on standing: passivate immediately after rinse.
Storage Notes
Cool, dark bottle. Per PACE SDS, stable longer than bench-mixed equivalents. Replace when activity drops.
Alternative Etchants
- Ammonium Hydroxide + H2O2
- ASTM No. 30
- Copper No. 1
- Copper No. 2
Similar Etchants
- Ammonium Hydroxide + H2O2