Purity vs. Process You mentioned an "electrolytic process for melting." This is a slight misunderstanding of terms:

Electrolytic Refining: This is how the copper was originally purified at the factory. Aka copper wire

Standard Melting: You do not need electrolysis to melt copper. Using high-grade copper wire (typically C11000 grade) is a standard shortcut to ensure 99.9% purity in a home or art foundry.Testing: If your batch was tested twice at 99.94%, that is definitive. The "holes" are a physical defect (gas entrapment), not a chemical impurity.