In supplement manufacturing, consistency is a priority. However, it is important to understand that consistency does not always mean absolute visual uniformity. Even when a formula remains unchanged, minor variations in tablet appearance can occur between production batches. These differences are normal within controlled manufacturing tolerances and do not indicate a change in quality, safety, or ingredient levels. This article explains the types of variation that can occur in tablets and why they happen.
1. Thickness Variation
One of the most noticeable differences between batches can be tablet thickness. This is typically influenced by compression force during tableting. Tablets are formed by compressing powder or granules inside a die cavity. If compression pressure is slightly higher, the tablet may be thinner and harder. If slightly lower, the tablet may be marginally thicker.
Manufacturers operate within validated specifications for weight, hardness, and thickness. As long as tablets fall within these approved ranges, they are considered compliant and fit for sale. A small difference in thickness does not mean the dosage has changed.
2. Hardness and Density Differences
Hardness refers to how firmly a tablet has been compressed. Density can vary slightly between batches due to small changes in powder behaviour, even when the ingredient quantities remain identical. Factors that influence this include:
- Natural variation in raw material bulk density
- Particle size distribution
- Moisture levels in excipients
- Environmental humidity during production
Even when suppliers and specifications are consistent, natural raw material variation can affect how a blend compacts during manufacture.
3. Colour Variation
Tablets containing botanicals or natural ingredients may show slight colour differences between batches. Plant-derived materials are subject to seasonal and agricultural variation. Soil conditions, harvest timing, and drying processes can all influence shade.
This is especially common in products containing herbal powders or extracts. A slight change in tone does not indicate a change in formula or strength.
4. Surface Finish and Edge Definition
Tablets may sometimes appear slightly smoother, more matte, or have subtly different edge definition between batches. This can result from:
- Tooling wear (punch and die sets naturally wear over time)
- Different tooling sets used on different production runs
- Minor adjustments to machine speed
All tooling operates within manufacturing tolerances, but micron-level differences can produce small visible changes.
5. Weight and Fill Consistency
Every batch undergoes in-process weight checks to ensure the correct fill weight is achieved. However, it is important to note that tablets are controlled primarily by weight and active content not by exact physical dimensions. Two tablets may look slightly different in thickness but weigh the same and contain the same amount of active ingredients. Regulatory compliance focuses on accurate dosage and safety, not identical appearance across all batches.
6. Storage and Environmental Factors
Post-manufacture conditions can also influence appearance. Tablets stored in environments with higher humidity may absorb small amounts of moisture, particularly if they are uncoated. This can cause slight swelling or surface texture changes over time.
Desiccant inclusion and correct storage guidance help minimise this, but small differences can still occur depending on distribution conditions.
Why Batch Numbers Matter
When variation is reported, batch numbers are essential for investigation. They allow us to:
- Trace the exact production run
- Review compression force settings
- Confirm in-process thickness and weight checks
- Verify raw material lot numbers
- Confirm tooling used
- Review finished product testing results
Without batch numbers, it is not possible to determine whether products came from the same manufacturing run or to review the quality control data that confirms compliance at the time of production.
Batch traceability is a core part of good manufacturing practice and ensures that any query can be properly investigated using documented production records.
Reassurance for Nutribl Private Label Clients
Minor physical differences between batches are a recognised and accepted part of tablet manufacturing. They do not indicate reformulation, under-dosing, or quality concerns when products remain within validated specification limits.
At Nutribl, every batch is manufactured under controlled conditions with documented quality checks to ensure weight, active content, and safety standards are met. While slight visual variation can occur, the integrity of the formulation and its compliance with regulatory standards remain unchanged.
If ever in doubt, batch traceability allows full review and confirmation.