Saccharin

Product Overview

Saccharin (o-Sulfobenzimide, C7H5NO3S) is the most important stress-reducing agent in modern bright nickel plating. Although chemically it is the same compound as the old artificial sweetener, plating-grade saccharin is a white crystalline powder of ≥ 98% purity, sold on content (not on sweetness). In a nickel bath it does two jobs at once: it reduces internal tensile stress of the nickel deposit (preventing cracks and peeling) and it refines the grain, which raises brightness and leveling. Market grades commonly seen: industrial grade 98%+ and premium 99.5%+ with lower o-sulfamoylbenzoic acid (insolubles). Cheap grades with high insolubles leave rough, hazy deposits and clog filters.

Product Identity (Encyclopaedia Card)

What it is and what it does. Saccharin (and its sodium salt) is the primary brightener of the nickel plating bath. It is the classic secondary brightener that gives the deposit its levelled, mirror-bright appearance by refining the grain.

• White crystalline powder; used at 0.5-2 g/L in the Watts nickel bath.
• It reduces internal stress and increases the sulphur content of the deposit, which is what gives the bright levelled finish.
• Overdosing increases the sulphur level and makes the deposit more susceptible to corrosion in the layered bright nickel systems.

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 Dosage Matters)

Saccharin adsorbs on the growing nickel surface and co-deposits in trace amounts (sulfur incorporation of 0.02-0.04%). This sulfur co-deposition is exactly what reduces tensile stress and later gives the bright nickel layer its anodic, sacrificial behavior over semi-bright nickel in double-layer systems. But it is a "more is worse" additive:

Typical consumption: 15-30 g per 1000 Ah passed. In a busy barrel line running 500 Ah/day that is roughly 100-150 g per week - topped up by amp-hour dosing, not by feel.

Quality Checks Before Use

How QLQ controls it: each lot is Hull-cell verified in our own nickel bath before release. Because saccharin quality decides whether your chromium sticks the next day, we keep a retained sample of every lot we ship for 12 months - if your bath misbehaves, we re-test the exact batch you used.

Handling & Safety

• Toxicity: low acute toxicity, but plating-grade material is not food grade - gloves and dust mask when weighing; wash hands after handling.
• Dissolving: make a 10-20% stock solution in warm water and dose by amp-hour meter; never dump dry powder straight into the production bath (local over-dose = passive patches).
• Storage: dry, sealed, away from oxidizers. Caked powder still works if fully re-dissolved, but caking means moisture got in - check purity on the next lot.
• Bath side effects: excess saccharin is hard to remove; only dilution or electrolytic purification at low CD helps. Add little and often.

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

FAQ

Bath misbehaving? Send photos of your panels to QLQ engineering - we diagnose saccharin/brightener balance remotely for customers in 10+ countries. Contact us.