All in order: – To prevent darkening of wood and reduce the absorpability of varnish in it, first make a primer. This is mainly done by a primer from nitro -cellulose, but it is quite acceptable to use standard nitrolaki. Speaking of the last option, pay due attention to the color.- after drying you need to polish the surface. In the case of applying varnish to wood, in order to prevent the appearance of blue and other defects, first soak it with any antiseptic. It is worth saying that this can be done by professionals whose services can be viewed on the Internet, where you can see various ads how to buy a house in the Tver region, hold overhaul, as well as sex varnishing services.- If you varnish the floor with the current coating, pay attention to the preparation of the coating. So that the floor is carefully cleared of various kinds of pollution. It is better to remove the dust from grinding with a damp cloth without a pile.- If the old initial coating is quite seriously worn out, then the floor must be polished to clean wood.- it must be borne in mind that the application of water varnishes directly to wood may be accompanied by a general raising of the pile. After the grinding process, the wood must be slightly moisturized, and after drying, once again polish.- When the final layer of primer dries, you can safely proceed directly to the process of applying varnish.