# Dry-basis calculations for WPC formulation

Canonical: https://woodplasticcomposite.net/guides/dry-basis-calculations-for-wpc-formulation/
Language: en
Updated: 2026-10-15
Version: 1
Review: AI-assisted English editorial draft. Human technical review has not been recorded.

## Summary

A WPC recipe needs a declared moisture basis before ingredient percentages can be compared. Water arriving with wood flour is not dry reinforcement and should not quietly replace polymer in the calculation.

## Technical context

Consider an illustrative delivery containing 100 kg of wood flour at 8% moisture on a wet basis. It contains 92 kg dry wood and 8 kg water. That is a bookkeeping example, not a recommended extrusion moisture target. Dry-basis moisture would use a different denominator.

https://woodplasticcomposite.net/guides/dry-basis-calculations-for-wpc-formulation/#technical-context

## What to measure and document

Ask the laboratory to state the moisture method and denominator. Record delivered mass, dry solids and any losses separately. Reconcile a trial batch against the final dry composition before comparing its mechanical results with another recipe.

https://woodplasticcomposite.net/guides/dry-basis-calculations-for-wpc-formulation/#verification-plan

## Implications for development and specification

A purchasing specification should identify whether fibre content is as received or dry mass. Keep acceptance limits separate from calculation examples. This makes supplier comparisons clearer without demanding disclosure of every proprietary additive.

https://woodplasticcomposite.net/guides/dry-basis-calculations-for-wpc-formulation/#practical-decision

## Related reading and evidence limits

An engineering-statistics introduction to systematic experimental design. Use the linked work as related reading. The practical checks above are editorial recommendations, not reported test results or a substitute for product qualification.

https://woodplasticcomposite.net/guides/dry-basis-calculations-for-wpc-formulation/#reading-scope

## Key points

Consider an illustrative delivery containing 100 kg of wood flour at 8% moisture on a wet basis.
Ask the laboratory to state the moisture method and denominator.
A purchasing specification should identify whether fibre content is as received or dry mass.

## Comparison

Review step | Evidence to retain
Material and geometry | Exact specimen or product identity
Verification | Method, conditions and individual observations
Decision | Approved scope and documented limitations

## What evidence is needed for dry-basis calculations for WPC formulation?

Ask the laboratory to state the moisture method and denominator. Record delivered mass, dry solids and any losses separately. Reconcile a trial batch against the final dry composition before comparing its mechanical results with another recipe.

## Sources

1. NIST: design of experiments — https://www.itl.nist.gov/div898/handbook/pmd/section3/pmd31.htm