Applying the stain
Okay, now for the fun part. You’ve gotten the floor so clean you could eat off of it, but you wouldn’t because you don’t want to get it dirty. The floor is completely dry and you have all of your equipment at hand. The floor is ready for stain.
Wait! Have you any doubts about this project? We have a great idea (and a prudent one to boot). Test an inconspicuous area of your floor. Under a cabinet, behind a semi-permanent piece of furniture, whatever. Go through the first steps of the acid stain application (two coats and then clean off the stain). You will be able to see the approximate color and stain acceptance of the final product. If you get the stained area slightly wet, you will get an idea of what the stain will look like with sealant and wax.
Fill a plastic garden sprayer with stain.
It is important that an all-plastic garden sprayer is used because the acid will react with any metal it comes in contact with. The stain doesn’t really clog the sprayer and the spray pattern is not all that important, so don’t be afraid to buy a cheap sprayer.
Spray on the stain.
Apply the stain in an even distribution. Keep track of how much stain you add to the sprayer (ie 2 gallons) and then monitor how much area you are covering to see what kind of coverage you are getting. A common mistake that DIY’ers make is to apply too much stain. Only apply stain to as large an area as you can reach with the scrubber.
Scrub in a figure eight motion. Do one section at a time. Overlap edges.
This picture shows how active stain can fizz slightly. That is a good sign.
First coat complete.
Let the stain dry.
The first coat of stain should dry at least five hours, but preferably longer. The longer the stain dries on the concrete, the darker the stain tends to be. Be careful of wet spots on the floor; the stain is very very slippery when wet!
Apply a second coat of stain.
A second coat of stain is necessary for a satisfactory application. You should apply about the same amount of stain as you did on the first round (or slightly less). Again, the stain should be scrubbed in section by section. By the way, this is not what your floor will look like! It is probably much darker and splotchier than the finished product, so don’t get excited yet!
Let the second coat dry.
The second coat of stain should dry for 24 hours. At this point the floor will probably start to look kind of gross as the stain solids build up and dry. Much of this will come off as residue. Once the stain has completely dried you are ready to clean the floor again!
Next: Cleaning the stain.