Sometimes wood needs to be re varnished or restrained. To remove old varnish, you can use either a paint stripper or sand off the old varnish.
you have to brush it
You'll need to use some lacquer thinner and a wire brush to remove any varnish on brick.
Varnish preserves wood better than paint.
You can remove varnish from tiles by making a paste that contains two parts calcium carbonate, one part trisodium phosphate and some water. Using a putty knife, spread the paste over the varnish and allow to sit for 30 minutes. Use a plastic putty knife to remove the paste and varnish, scraping along the tiles as you go to remove as much of the varnish as possible. Rinse the tiles with warm water and pat dry with a clean, dry cloth.
To remove varnish from any surface, use Acetone. Acetone is also in nail varnish remover.
A stain is used to color the wood while a varnish is a topcoat used to protect the wood.
Wood wax is a type of varnish/polish
Varnish is to highlight and preserve bare wood.
This depends on the severity of the scratch. Some of them can be fixed with a lick of wood varnish. Some of them are more severe and need to be sanded down before applying a new coat of varnish. If this isn't possible, then you'll have to replace at least part of the floor.
No it is not safe to burn it.
Yes, acetone can be used to remove varnish. You must work on small areas at a time, as it evaporates quickly, in the direction of the wood grain. Also make sure to use lint free cloths when applying the acetone. Make sure you clean the surface well when you are done, as these solvents tend to leave residue behind. Then you can proceed to apply the varnish.
there are many ways you can. you can use a name brand stain remover, like SHOUT. or you can hand wash it with regular soap.