Hard vs Soft Gelatin Capsules: A Manufacturer's Guide to Choosing the Right Grade
Not all pharmaceutical gelatin is interchangeable. Ask a capsule manufacturer whether they need "gelatin" and the honest answer is: it depends entirely on whether the line runs hard capsules or softgels. The two processes place different demands on Bloom strength, viscosity, and moisture content — and getting the grade wrong doesn't just affect product quality, it can stop a production line.
This guide builds on our general overview of pharmaceutical gelatin by going deeper into the specific decision procurement and R&D teams face when specifying gelatin for hard-shell capsules versus softgels.
Hard Gelatin Capsules: How They're Made and What Gelatin They Need
The Dip-Molding Process, in Brief
Hard capsule shells are produced by dip-molding: pairs of precision stainless-steel pins, shaped to the exact dimensions of the cap and body, are dipped into a heated aqueous gelatin solution (typically around 25–30% w/w gelatin, held near 50°C). As the cooler pins meet the warmer solution, a thin gelatin film sets on their surface. The pins are then withdrawn, rotated to distribute the film evenly, and dried before the cap and body sections are trimmed, joined, and ejected. Caps and bodies form simultaneously on opposite ends of the same machine.
Because the shell has to hold its shape as a rigid, self-supporting structure before it's ever filled, the gelatin used here needs different functional characteristics than gelatin destined for a softgel.
Typical Bloom and Viscosity Range for Hard Capsule Shells
Industry references consistently place hard capsule gelatin in a higher Bloom strength band than softgel gelatin — commonly cited ranges run from around 200 to 280 Bloom for hard-shell applications, compared with roughly 150 Bloom (sometimes lower) for softgels. The higher Bloom strength gives the dried shell the rigidity it needs to survive filling, banding, and packaging without cracking or deforming. Viscosity matters just as much: solution viscosity governs how the film builds on the dipping pin. Too high, and the shell comes out thick and slow to dry; too low, and it's thin, uneven, and brittle — the exact working range varies by formulation and equipment, and is typically confirmed against each supplier's technical data sheet rather than a single industry-wide number. We explain how Bloom strength itself is measured and why it's chosen differently across applications in Bloom Strength Explained and How to Determine Gelatin Strength.
Hard capsules are also only one of two common shell materials on the market — for context on how gelatin shells compare with cellulose-based (HPMC) alternatives, see our earlier article, Gelatin or Cellulose Capsules: Which to Choose?
Soft Capsules (Softgels): Unique Requirements
The Rotary Die Encapsulation Process
Softgels are produced by an entirely different method: the rotary die process, developed in the 1930s and still the industry standard. Here, plasticized gelatin mass is cast onto two cooled rotating drums, forming continuous, thin gelatin ribbons. These ribbons are fed simultaneously into a rotary die assembly, where a liquid, suspension, or paste fill is injected between them at the exact moment the dies cut and seal each capsule — forming, filling, and sealing in a single continuous operation. It's a fundamentally different mechanical challenge than dip-molding a rigid shell: the gelatin has to flow into a uniform, defect-free ribbon and then seal cleanly around a liquid fill under pressure.
Plasticizers, Elasticity, and Why Softgel Gelatin Behaves Differently
The defining difference in softgel gelatin isn't just a lower Bloom strength — it's the addition of plasticizers, typically glycerin, sorbitol, or a combination of the two, at concentrations far higher than anything used in hard capsule shells. Where hard capsule shells use plasticizer sparingly, softgel shell formulations commonly run 20–30% plasticizer content, which is what gives the finished capsule its characteristic soft, pliable texture rather than a rigid one. Getting that ratio right is a formulation exercise in its own right: too much glycerin and the shell turns sticky and prone to leaking; too much sorbitol and it can become brittle or crack. The gelatin itself needs to be well-suited to this chemistry — consistent enough in Bloom and viscosity that the same plasticizer ratio produces the same shell behavior, batch after batch.
Key Parameters Compared: Bloom, Viscosity, Moisture
| Parameter | Hard capsule gelatin (typical) | Softgel gelatin (typical) |
|---|---|---|
| Bloom strength | ~200–280 g Bloom | ~150 g Bloom (sometimes lower) |
| Viscosity | Moderate; tuned for uniform pin-dipping | Tuned for smooth, continuous ribbon casting |
| Plasticizer content in shell | Minimal | High (commonly 20–30%, e.g. glycerin/sorbitol) |
| Forming process | Dip-molding on steel pins | Rotary die, cast ribbons |
| Shell character | Rigid, self-supporting | Flexible, pliable |
Note: these ranges reflect widely cited industry benchmarks and vary by pharmacopoeial standard, capsule size, and specific formulation. Always confirm exact specifications against your own product requirements and your supplier's Certificate of Analysis.
Why Moisture Content Is a Critical, Often-Overlooked Parameter
Bloom strength and viscosity get most of the attention, but moisture content deserves equal scrutiny. Both parameters are typically measured and reported at a standardized moisture level — commonly 11.5% — precisely because gelatin's functional properties shift with its water content. Too much residual moisture in a finished shell creates a risk of microbial growth during storage and can compromise mechanical stability; too little, and shells become brittle. For a manufacturer exporting to markets across different climates — from humid coastal regions to dry continental ones — consistent moisture control at the source is what keeps shell behavior predictable regardless of where the finished capsule ends up.
Why Grade Consistency Matters for Capsule Production Lines
Batch-to-Batch Variability and Its Impact on Line Stability
A capsule production line is calibrated around a specific gelatin behavior: a given dipping time, a given ribbon thickness, a given drying curve. When Bloom strength or viscosity drifts between batches — even within a nominally acceptable range — that calibration starts to work against the operator. Shells may dry too slowly or too quickly, ribbons may vary in thickness, and the practical result is an increased risk of sticking, deformed capsules, or rejected batches. In a running production environment, that translates directly into downtime and yield loss, not just a quality footnote.
How a Controlled, Integrated Supply Chain Supports Consistency
This is where the structure of a supplier's own operation matters as much as its published specification sheet. Brodnica Gelatin has operated as an integrated, single-site Polish producer since 1937 — more about our history and operations — which allows tighter control over raw material sourcing and processing conditions than a supply chain assembled from multiple intermediaries. For a capsule manufacturer, that translates into fewer surprises between one delivered batch and the next.
Documentation: What Your Supplier Should Provide
COA, TDS and Pharmacopoeial Compliance Statements
For any pharmaceutical or nutraceutical capsule application, documentation isn't optional. At minimum, expect a Certificate of Analysis for every batch, covering Bloom strength, viscosity, and moisture content among other parameters, alongside a Technical Data Sheet describing the full specification. Where relevant, a statement of compliance with applicable pharmacopoeial monographs (such as Ph. Eur. or USP-NF) should also be available. Our article on GMP in Pharmaceutical Gelatin Production goes into more detail on the standards that underpin this documentation.
Quality Certifications That Support Your Own Regulatory File
Beyond batch-specific paperwork, a supplier's system-level certifications form part of the evidence base your own quality and regulatory teams rely on. Brodnica Gelatin holds ISO 9001, ISO 22000, BRC, and HACCP certifications — see our full certifications page — which provide the documented quality management framework that a pharmaceutical or nutraceutical buyer's own audit process will typically require from a raw material supplier.
Frequently Asked Questions
What is the main difference between hard and soft gelatin capsules? Hard capsules consist of two pre-formed shell halves — a cap and a body — that are manufactured separately by dip-molding and then filled, typically with powders or granules. Soft capsules (softgels) are formed and filled in a single continuous rotary die process, usually with a liquid, suspension, or paste fill. The gelatin used for each is formulated differently to suit these distinct manufacturing methods.
Does hard gelatin capsule production require a different Bloom strength than softgel production? Yes. Hard capsule shells generally use a higher Bloom strength, often cited in the 200–280 g range, to achieve the rigidity needed after dip-molding and drying. Softgel gelatin is typically lower in Bloom strength and is formulated together with plasticizers to produce a flexible, pliable shell rather than a rigid one.
Why does gelatin viscosity matter for softgel encapsulation? Viscosity governs how the gelatin mass flows and forms a continuous, uniform ribbon during casting. Inconsistent viscosity can lead to uneven ribbon thickness, which affects fill accuracy, seal quality, and the structural integrity of the finished capsule.
What documentation should a pharmaceutical-grade gelatin supplier provide? At minimum, a Certificate of Analysis for each batch, a Technical Data Sheet with full specifications, and — where applicable — a statement of compliance with relevant pharmacopoeial standards. Evidence of system-level quality certifications, such as ISO and BRC, supports your own supplier qualification and regulatory documentation.
How does batch-to-batch consistency affect a capsule production line? Variability in Bloom strength, viscosity, or moisture content between batches can shift gelling time and shell behavior on the line, increasing the risk of production delays, misshapen capsules, or sticking — which makes supplier consistency a direct factor in line uptime and product quality, not just a paperwork concern.
Talk to a Manufacturer That Understands Both Capsule Types
Choosing the right gelatin grade isn't a one-size-fits-all decision — it depends on whether your line runs hard-shell dip-molding or rotary die softgel encapsulation, and on the specific tolerances your formulation and equipment demand. Brodnica Gelatin has supplied pharmaceutical and nutraceutical manufacturers across markets on four continents for decades, backed by ISO 9001, ISO 22000, BRC, and HACCP certification and a single, integrated production site in Poland.
If you're specifying gelatin for a hard capsule or softgel line, explore our product offer or contact our team to discuss specifications, documentation, and sample batches for your application.