Copper Sulfate

Product Overview

Copper Sulfate (CuSO4·5H2O) - blue vitriol - is the main salt of the acid copper plating bath, the workhorse that lays down the level, bright copper underlayers under nickel-chrome on zinc die cast and steel, and the thick builds used in electroforming and rotogravure. In QLQ's finishing plants acid copper from copper sulfate produces the smooth undercoats that make zipper sliders and belt buckles look like jewelry instead of stampings. The commercial market sells many grades: plating grade (crystal, low iron and chloride, essentially free of organic residue), agriculture and feed grades, and even crude industrial material. Only the plating discipline matters here - copper sulfate is judged by what is not in it. Iron above a few hundred ppm dulls and hardens the deposit and slows the bath, chloride shifts the delicate chloride balance that proprietary brighteners need, and organic residue roughens and hazes. A bright acid copper bath is an additive machine with a narrow tolerance, and its fuel must be clean.

Product Identity (Encyclopaedia Card)

What it is and what it does. Copper sulfate is the general technical grade copper salt used for acid copper plating, for making up copper anode films, for antiquing solutions and for copper recoating of damaged plating racks.

• The familiar blue crystal; the same substance as the pentahydrate product, offered here in the general technical grade and in a wider range of pack sizes.
• Used to prepare the copper complex for antiquing and for thin protective copper layers on steel before nickel.
• Copper ions are toxic to aquatic life, so spent solutions go to the effluent treatment plant and never to drains.

Typical Use in a Plating / Finishing Line

Safety, Handling & Storage

Quality Documents Shipped With Every Batch

Buyer Questions We Answer Every Week

How It Works in the Bath (Acid Copper Chemistry)

Acid copper is a two-component electrolyte: copper sulfate supplies the metal ions that plate out, and sulfuric acid supplies conductivity and keeps the bath stable while suppressing the copper-ion concentration at the cathode so the deposit levels and brightens under the additive system. In the classic decorative bath the make-up is roughly 200 g/L copper sulfate and 60-80 g/L sulfuric acid, with 40-80 mg/L chloride and the supplier's brightener/leveler package; high-throw formulations used in PCB work invert the ratio (low copper, 180-220 g/L acid) to plate deep holes evenly. Air agitation and continuous filtration are not optional - acid copper is dead without them, because the brightener depends on strong, uniform solution movement. Anodes are phosphorized copper (about 0.03-0.06% phosphorus), which dissolve cleanly and leave a black film that holds back anode sludge instead of releasing particles that roughen the deposit.

The same salt serves the alkaline (cyanide) copper line only as a source for making up copper cyanide concentrate - it is never added to a cyanide bath directly, because acid salts liberate hydrogen cyanide gas in cyanide solution.

How to Check Quality Before Loading a Batch

How QLQ controls it: copper sulfate lots are quarantined until the copper, iron and chloride figures on the COA match the purchase order, and a Hull cell panel confirms the lot plates identically to the retained standard before it is released. The lot number goes into the make-up record, so a leveling or brightness change can be traced to the salt in a day.

Common Problems & Fixes (Workshop Table)

Handling & Safety for the Plating Line

• Health: copper sulfate irritates eyes, skin and airways; it is harmful if swallowed. Wear gloves, goggles and a dust mask when handling crystals and making up solution.
• Dissolving: copper sulfate dissolves readily in warm water (about 30-40°C) with stirring; do not boil. Acid is added to the diluted salt solution - never water into acid.
• Effluent: copper is tightly regulated in rinse water (typically ≤ 0.5-2 mg/L discharge limits). Collect spills and spent solutions as copper-bearing waste; do not hose to drain.
• Storage: keep bags sealed and dry. The pentahydrate effloresces in dry air and cakes in damp air - either way weighing accuracy suffers.
• Cyanide rule: never allow acid copper solution near cyanide baths or cyanide waste - mixing acid with cyanide liberates hydrogen cyanide gas.

What It Does on Iron, Zinc Alloy, Copper and Stainless Steel Parts

FAQ

Acid copper rough, dull or not leveling? QLQ supplies plating-grade copper sulfate with COA and engineers who help customers in 10+ countries run decorative and high-throw copper lines. Contact us with your Hull cell panels.