Specialist desiccants and additives used in a wide range of applications


Masterox calcium oxides are powerful desiccants that can alleviate problems such as extrusion blow out or surface defects, which can develop during the processing of thermoplastic compounds.  These problems arise due to the presence of moisture.

Moisture can be present in raw materials e.g. polymers (especially hydroscopic types such as ABS, polyamides etc.), fillers and plasticisers. As little as 0.02% moisture can cause extrusion blow out or surface defects in the end product if it is allowed to expand freely into water vapour at polymer processing temperatures. The addition of Masterox is the most efficient and cost effective solution to eliminate these problems.

Masterox microfine powders disperse easily and evenly throughout the product mix to give consistent results.  Addition rates depend on which application it is used in, formulation and local conditions.

Birch Chemicals is unique in that we have an integrated supply chain which gives Masterox products unrivalled performance due to their consistency, control and traceability.

Mode of action

Calcium oxide reacts exothermically with water, generating heat and converting to calcium hydroxide. The calcium hydroxide formed acts as an inert filler in the end product. Innovox high activity calcium oxide will chemically bind up to 32% of its own weight in moisture.

The decomposition temperature of calcium hydroxide is approximately 530°C, well above the typical processing and service temperatures of plastics.

Available locally from our network of global distributors.

Looking for more info?

Call: +44 1652 686080

For further information on the advantages of using Masterox, please download the product information leaflet below.


Masterox range product information leaflet.


Birch Chemical’s standard grade calcium oxide powder.

Safety data sheet

Masterox 10

Birch Chemicals microfine grade calcium oxide powder.

Safety data sheet