Gelatin

Product Overview

Gelatin is a purified protein colloid obtained by controlled hydrolysis of collagen, sold for electroplating as a grain refiner and leveling agent for acid copper and matte tin baths. In the plating tank gelatin does not react like a metal salt: it adsorbs on the growing cathode surface and temporarily slows deposition on peaks and protrusions, so the deposit grows smoother, finer-grained and more uniform. Market grades are the key decision point: technical/photographic grade (low ash, low chloride, low heavy metals, controlled jelly strength) is made for process baths, while edible and food-grade gelatins contain sulfite and other preservatives plus variable jelly strength and must not be used in plating. Cheap or over-aged lots hydrolyze into peptides that cause hazy, streaked deposits. QLQ selects low-ash technical gelatin with a documented jelly strength range and no preservatives for its plating-chemical program.

Product Identity (Encyclopaedia Card)

What it is and what it does. Gelatin is a traditional protein brightener and levelling agent for acid copper, bronze and brass baths, where it refines the grain and improves the throwing power of the deposit.

• Pale yellow to amber granules; dissolved in hot water before addition and dosed by the analysis or the Hull cell.
• Protein brighteners decompose slowly in the bath and their breakdown products also affect the deposit, so the level must be watched.
• Widely used in barrel bronze and brass plating of zipper sliders, where it gives a warm semibright deposit.

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 (Dose-Response)

Gelatin molecules are long-chain proteins that diffuse to the cathode and adsorb preferentially where the current density is highest - exactly where a deposit would otherwise grow fastest and roughest. The adsorbed film raises the activation energy for metal deposition at those points, letting low-current areas catch up. The result is a smoother, denser, finer-grained deposit. Because the effect is physical adsorption, gelatin is consumed continuously and its breakdown products accumulate, which makes it a classic “little and often” additive:

In matte tin plating the working range is higher (1-2 g/L, usually with β-naphthol) because the sulfate tin bath operates at higher temperature and consumes the colloid faster. Typical gelatin consumption in a decorative acid copper line is 2-5 g per 1000 Ah; top up in small doses after a Hull cell check rather than on a fixed calendar.

Typical Bath Formulations (Working Ranges)

These are workshop-proven starting ranges for zipper and hardware lines; fine-tune 10-20% for water quality and loading ratio. Gelatin alone gives a semi-bright copper; where mirror copper is required it is combined with proprietary levelers or used as a backup leveler in formulations.

Quality Checks Before Use

How QLQ controls it: every incoming gelatin lot is quarantined until the COA (Bloom value, ash, chloride, heavy metals) is checked and a Hull cell panel is run in a live acid copper bath. Because one high-ash or sulfite-preserved lot can contaminate an entire copper line, each shipped batch is traceable by number and a retained sample is kept for 12 months for re-testing.

Common Problems & Fixes (Workshop Table)

Handling & Safety

• Health: gelatin is an animal protein powder; wear a dust mask and gloves when weighing. Dust can irritate the respiratory tract and protein is a sensitizer for some people.
• Dissolving: pre-swell in cold or lukewarm water for 20-30 minutes, then warm gently to 45-55°C with stirring. Never boil - heat above 60°C degrades the colloid and destroys its leveling power.
• Stock hygiene: aqueous gelatin stock supports bacteria and fungi, especially in tropical weather. Prepare small weekly volumes and store refrigerated or in a cool place; discard if it turns cloudy or smells.
• Storage: keep bags sealed in a cool, dry store. Heat and humidity accelerate hydrolysis; a lot older than 12 months should be Hull-cell re-verified before use.
• Waste: gelatin is biodegradable and adds only organic load; it does not complicate metal-bearing effluent treatment, but carbon-treatment sludge is still hazardous because of adsorbed metals.

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

FAQ

Copper deposit rough or hazy? Send Hull cell photos to QLQ engineering - we diagnose additive balance for plating customers in 10+ countries. Contact us.