Cristobalite

Cristobalite (silica, chemical formula SiO₂) is the result of the calcination of quartz at a temperature of 1500°C:

 

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Cristobalite can be characterised by:

 

• High brightness
• Relatively high Mohs hardness of 6.5
• Relatively low refractive index, making it a transparent filler in various binders
• Easy wetting
• High inertness in various media
• Transparency for UV-radiation (ie. suitable for UV-curing processes).

 

Note when using cristobalite: depending on the particle size distribution of the product, it can be labelled (STOT RE 2 or STOT RE 1). For more detailed information, visit www.safesilica.eu.

 

Basic properties

Property	Value	Unit
Moisture		[%]
pH	9	[-]
Hardness (Mohs)	6.5	[-]
Refractive index	1.48	[-]
Colour (D65/ 10°) L*	98	[-]
Density	2.3	[kg/ dm3]

 

Product overview

Coarse			Fine
Product	Grade	D50	Name	Grade	D50	D90	OA
		[µm]			[µm]	[µm]
Sibelite	M72	310	Sibelite	M002	70	200	21
	M72T (1)	300		M006	40	100	23
				M0010	30	75	23.5
				M3000	17	40	26
				M3500	10	30	26
				M4000	6	12	27
				M6000	4	8	28

(1): Tamisé: > 500 µm = < 1%

Production locations Sibelite

 

 

Application

Cristobalite will provide:

 

• Dirt pick-up resistance: the presence of cristobalite improves the coating’s resistance to dirt (from the  atmosphere, for example).
• Ease of tinting: due to the combination of refractive index, brightness and color, paints including cristobalite will give excellent reproducible colour results when working with tinting systems.
• Texture effect: usage of coarse cristobalite grades will ensure texture to the surface of the coating.
• Tint retention: paints including cristobalite show improved tint retention over other minerals when subjected to natural weathering
• UV resistance and weatherability: due to its inertness, cristobalite supports good UV and weatherability performance to exterior architectural coatings.