Boric Acid

Product Overview

Boric Acid (H3BO3) is the standard pH buffer of nickel and cobalt plating. Added to Watts nickel, sulfamate nickel and nickel electroforming solutions at 30-50 g/L, it holds the cathode film pH in the range where nickel deposits smoothly instead of precipitating basic nickel salts that burn, roughen and pit the work. In QLQ's finishing plants boric acid is part of the bright nickel, semi-bright nickel and nickel electroforming baths behind zipper sliders, belt buckles and small hardware. It is a white crystalline powder, mildly acidic in solution, fully water soluble, and it has no plating role in acid copper or zinc baths - it is bought for nickel and cobalt lines and for nothing else. Two commercial families exist: technical/plating grade (≥ 99.5% assay, low chloride, sulfate and heavy metals) and agricultural/fertilizer grades sold on boron content alone, which can carry chloride and metal residues. For a plating tank the assay and impurity spec matter more than the boron figure, because a nickel bath has no appetite for chloride or iron.

Product Identity (Encyclopaedia Card)

What it is and what it does. Boric acid is the buffer of the nickel plating bath. It holds the cathode film pH in the range where nickel deposits brightly, and it is the classic additive that improves the appearance of nickel and cobalt deposits.

• White crystalline powder, only slightly soluble at room temperature - its limited solubility is the reason the bath analysis drifts.
• Buffers the cathode film near pH 3.8-4.5, preventing hydroxide inclusion and pitting.
• Also used as a flux, as a fire retardant and as a mild cleaner ingredient.

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 (Why Buffer Range Matters)

At the cathode, hydrogen evolution raises the pH of the thin film of solution against the part. If nothing stops that rise, nickel hydroxide and basic nickel salts form in the film and are dragged into the deposit as dark, rough or burnt growth at high current density. Boric acid works as a buffer right where it is needed: it is present at 40-50 g/L in the bulk, it migrates and adsorbs at the cathode film, and it absorbs the hydroxyl ions that hydrogen evolution produces, holding film pH near the bath pH of 3.8-4.8 instead of letting it climb past about 5.5 where nickel hydroxide precipitates. The practical symptoms of weak buffering are burning and roughness at edges, pH drift between additions, and milky deposits after shutdowns. Below about 30-35 g/L a nickel bath loses its safety margin and burns parts at the very current densities every decorative rack and barrel line uses.

Boric acid dissolves slowly in cold water and is close to its room-temperature solubility limit at the working 40-50 g/L, so make-up is always done in hot water and analysis is done by titration, not by topping up on a schedule.

How to Check Quality Before Loading a Batch

How QLQ controls it: boric acid deliveries are checked against COA assay, chloride and iron figures before the bags enter the nickel-line store, and a full tank analysis is run whenever a new lot is first used. The recorded lot number lets the lab trace any pH or deposit anomaly back to the exact delivery within a day, which is how QLQ keeps nickel baths running for years without full dumps.

Common Problems & Fixes (Workshop Table)

Handling & Safety for the Plating Line

• Health: boric acid is classified as toxic to reproduction in the EU (R60-61); pregnant operators and pregnant workers should not handle the powder. Wear gloves and a dust mask when opening bags and weighing.
• Dissolving: always dissolve in hot water (60-80°C) with stirring; boric acid dissolves too slowly in cold water to be dosed directly into a working tank without local saturation.
• Dust control: fine crystals generate dust when bags are emptied; use a dust mask, empty slowly and keep the dosing area ventilated.
• Storage: bags stay sealed on dry pallets; boric acid does not degrade but absorbs damp and cakes, which slows dissolving and upsets weighing.
• Spills: sweep and re-use clean powder, or dissolve spilled material into the make-up water. Boric acid is not a drain hazard at shop concentrations, but do not bulk-discharge concentrated solution without checking local limits.

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

FAQ

Nickel bath burning edges or drifting pH? QLQ supplies plating-grade boric acid with COA and engineers who help customers across 10+ countries with buffer control and defect diagnosis. Contact us with your bath analysis.