UltraCarb is a natural halogen-free mineral that can be used as a fire retardant filler suitable for plastics and rubbers It is produced from a deposit of Hydromagnesite and Huntite.

Each of the two minerals – Hydromagnesite and Huntite (HMH) – are flame retardants on their own, the combination however results in a unique product which specific properties may be adjusted by selected mining and processing to fit a variety of applications.

UltraCarb rock and powder

UltraCarb product uses

UltraCarb is used as a fire retardant filler in a wide range of polymers such as polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC) and rubber.

UltraCarb in wire & cable

UltraCarb provides cost effective sustainable solutions to the global cable industry. Through its char formation when burning, the mineral combination brings a low smoke effect to PVC or rubber used in e.g. cable sheathing. The char also prevents the melting polymer from dripping which further prevents the fire to spread.UltraCarb in wire and cable

UltraCarb in foam insulation

In foam insulation UltraCarb replaces e.g. Aluminium Trihydroxide and is therefore the natural alternative for fire retardancy. The char formation prevents insulation foams to act as a fire accelerant and support it being a fire preventioner.

UltraCarb in rubber

In any rubber application where fire retardancy is necessary, UltraCarb is beneficial. UltraCarb can effectively reduce the rate at which flames spread across a flat surface and reduce dripping of molten polymer for applications such as conveyor belts or flooring.

UltraCarb properties

UltraCarb has a unique 3-stage fire retardant mechanism. Whereas the classical endothermic flame retardant fillers act by releasing water in a single action process, UltraCarb works as following:

  • Water is released at temperatures of ~220°C (thermal decomposition)
  • CO2 release at temperatures of ~330°C
  • At temperatures of ~560°C, UltraCarb particles accumulate at the surface of the burning polymer to form a stable cementitious char which inhibits the combustion process and thus the propagation of the fire through burning droplets.

3 stage fire retardant mechanism of UltraCarb


The platy, high surface area particles of UltraCarb provide excellent properties when used as a functional filler in polymers. The products' high heat absorption protects polymers from a rapid thermal degradation and the formation of combustible products.

Physical properties:

Specific gravity (g/cm³) 2.4
Refractive index 1.56
Surface area (m²/g) 11 - 17
Mohs' hardness 2.5
Loose bulk density (kg/l) 0.4

Chemical properties:

Magnesium as MgO (%)
36 - 39
Calcium as CaO (%)
6 - 9
Silica as SiO2 (%)
0.2 - 1
Loss on ignition at 1,000°C
51 - 54

UltraCarb standard grades

UltraCarb is available as coated and uncoated grades with a medium particle size of 1µm and topcuts (D98) ranging from 8.5µm to 16.5µm.

Primary Hydromagnesite   Primary Huntite

LH3 UltraCarb 1250
LH15 UltraCarb 1251
(stearate surface treated )
(stearate surface treated)
UltraCarb 1253
(proprietary surface treated)
(proprietary surface treated)
UltraCarb 1290
  UltraCarb 1291
(stearate surface treated)
  UltraCarb 1293
(proprietary surface treated)

Stearate surface treatment improves wetting and reduces the agglomeration in the compound, proprietary surface treatments are beneficial as an external lubricant, act as a processing aid for extrusion and improve the LOI in EVA.

UltraCarb packaging

Our UltraCarb product range is available in paper sacks, big bags or in bulk.

Hydromagnesite Huntite origin

Hydromagnesite and Huntite mineral deposits are formed by near surface thermo-chemical geological processes. The formation of ourTurkish desposits is the result of three specific conditions:

1. a depositional area of magnesium rich ultramafic basement rocks;
2. a lake environment which evolved into a basin;
3. tectonic activity: This allowed magnesium rich hydrothermal solutions to reach the surface.

The precipitation of Hydromagnesite and Huntite is related to the mixing of these hydrothermal solutions with fresh water from the lake environment.

Hydromagnesite Huntite toxicology

A non-toxic, non-hazardous stable mineral. You can download the Safety Data Sheet in the section on the right hand side for further information.

Please contact us for datasheets on a single grade or further information on our UltraCarb product range. You can find our sales contact by choosing your country in the upper right expert box of this page.

Product expert

Steve Banahan
Business Manager

Ask me a question. Contact information.

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