Solvent-based products are very effective materials, as they are much more forgiving regarding the parameters of the surface to be treated in terms of humidity, temperature and porosity. Moreover, most solvents have a lower density than water, hence a higher surface penetration capacity, especially when the material to be impregnated has high levels of moisture or reduced porosity. Typical examples for use are treating virtually non-absorbent materials lacking absorbency, such as compact natural stones formed in intrusive volcanic environments (granites and the like) or high-grade metamorphic rocks (gneiss, marbles and so on).
The downside is that they are polluting materials that release Volatile Organic Compounds (VOCs) into the air.
Today, regulations on reducing the environmental impact of such products are quite strict, deterring their use as much as possible and orienting the selection – as is right – towards more sustainable and technologically-advanced products.