Polish product, a very good substitute for Atlas Uni-Grunt and Cekol UNIVERSAL PRIMER G1 KLEIB G1 is a ready-for-use primer intended for all absorbent and porous surfaces such as gypsum boards,plasterboards, plasters (gypsum, cement and cement-lime), concrete surfaces, aerated concrete and ceramics.Thanks to its ability to even out the absorbency of a substrate, KLEIB G1 is particularly recommended to be used priorto painting surfaces with uneven absorption, e.g. surfaces partially covered in plasterboards or gypsum. This universalprimer should be used on walls and ceilings prior to the application of ceramic tiles. KLEIB G1 also strengthens slightlychalky surfaces. For old and very chalky substrates we advise using KLEIB G2 deep-penetrating primer.