The bottom should be clean, sturdy and free from any loose articles, dusts, paints, oils, grease, primer or old covers. It is necessary to fill and smooth all rough and porosity surfaces and any cavities among bullets by primer. Use Polyurethane mastic for movable seams. Mix both liquid & powder factors by an electric mixer (Drill & Blade). Pay attention that you should add powder component to the liquid one and the electric mixer should be on while adding the powder component to the liquid one. It makes better mix (Be sure to saturate the sub-sections with fresh water before performing the ready mix). Two-component water stop should be applied on wet parts. But no more fixed water should be available on surfaces. Apply the ready materials by a great brush for one set. Upon drying the first set, perform the second layer while it does not stick to hand. (The second layer should be perpendicular to the first one). Upon drying, wet the surface by spraying fresh water for 22 hours. Note: Do not perform a layer thicker than 1mm in each set.