Natural stone sealants

This article concerns the installation of Natural Stone using the natural stone sealant.
The question asked on a frequent basis is "what is the right way to apply a sealant or silicone when using natural stone? 
Otto-Chemie, (Otto) one of Europes leading Sealant manufacturers have produced a guide to the correct sealing of natural stone products. 
Jointing Natural Stone. 
Information on natural stone is rarely found in the current specialist literature, even though correct jointing is the final stage of the natural stone fitting process. Imperfectly formed joints or joints sealed with the wrong materials do not only render the work worthless, but can also result in costs arising from complaints, cleaning or damages caused. A company that economises on sealants is not only putting it's good reputation at risk but running the risk of economic consequences. 
As a leading manufacturer of sealants and adhesives, Otto has created this jointing guide for builders and designers, to sharpen the awareness on the type and extent of potential problems caused by the wrong sealant choice. 
Protection and Good Looks.  
Jointing natural stone is very different from other types of joint work. This is due to extreme conditions in the areas of application and to varied material properties that have to be taked into account. As well as meeting aesthetic conditions, a sealant used with natural stone and is subsequently reliable over many years from water or chemicals getting into or behind it. 
Threat from oily plasticizers. 
A disadvantage of many traditional silicones is the proportion of oily plasticisers which under heat or pressure can migrate into the outer edges of the stone, leaving ugly, undesirable stains.
Exposure to physical and chemical agents.  
What remains are the purley technical demands a natural stone sealant has to fulfill permenantly: These include high resistance to UV radiation, reliable adhesion to many different materials, flexibility under pressure and tension and notch resistance.
No staining of natural stone, guarenteed! 
Ottoseal S70 is a neutrally cross linking silicone sealant which is suitable for extremely demanding areas of application. It is very resistant to compression, tension and UV light; withstands wear and ageing and exhibits excellent adhesive properties.
Even under high pressure the dreaded migratory staining has no chance to happen when Ottoseal S70 is used. This has been proven and certified in tests according to rigorous US standards. Otto even guarentees this property to reassure the user as Ottoseal S70 contains no plasticisers. Its high content of silicone makes the sealant easy to be worked with and smoothed. The slow skin formation means that long lengths of joints can be made in one pass.
TIP: With sandstone, mask off the edges of the joint before applying Ottoseal S70, as it is dificult to remove stray spots from the surface of the stone. NB: Only use suitable masking tape that does not mark the stone. 
Use a back up material to avoid three sided adhesion. 
Filling up the joint with an appropriately sized PE Foam prevents contact with the "Third Size". Before the PE foam rod is positioned, the sides of the joint must be cleaned and if necessary pretreated with the correct primer to obtain optimal adhesion. 
Extreme exposure on facades.
With temperatures possibly ranging from -40C to +100C, exhaust fumes, precipitation and constant exposure to UV rays, sealants for facades need to be of a very high quality indeed. 
To stop water or emissions getting behind the stone, the sealant must offer permanent resistance to these extreme conditions and absorbe any movement of the facade caused by fluctuations in temperature. 
With it's outsdanding chemical and physical properties, Ottoseal S70 meets these challenges superbly. It's high resistance to UV and ageing make it a natural stone sealant which will maintain the value of a facade over many decades and helps to avoid costly maintenance and renovation work. Aditional assurance is given by the OTTO guarantee against migratory staining.