When we bought our house..we knew that someday we would be ripping up the carpet and laying tile or wood...never considering staining the concrete because it is so incredibly expensive. The first thing we did was rip up the carpet in our room because there was carpet in the bathroom....which to me is so disgusting. We put in a calico looking floor because we had a friend who had a bunch of left overs from different houses that he had laid. I love the effect it has. A couple of years later we decided to rip up the rest of the carpet and lay tile down..except for the back bedrooms. I love the coolness of tile and the fact that you can get it so clean you can eat off of it! We ended up ripping up the carpet in one of the back bedrooms and have been living off the ugly concrete that was splattered with paint, stain and dry wall from 20 plus years ago. I started researching painting, etching, and acid washing/staining concrete. I didn't want to paint because we have friends that have done that....and anytime you move furniture...there goes the paint...etching...too much trouble...and staining I love love love the way it looks...but it is way way to expensive...even for a small room...plus it's with acid.
When we went on a weekend retreat to the hills of Kingston...the place we stayed at had all acid washed concrete...or so I thought. I asked "Pete" if he had acid washed this entire building...it was pretty big..and thought it must of cost a fortune. He smiled and said no....we used ferrous sulfate...and did the entire house for around $50. WHAT???
So that's what we did.
I'm not going to lie...it's work...but because it is so cheap...it's worth it. Of course we were taking everything out of a very messy bedroom, ripping up carpet, tack strip...and then scrubbing 20 plus years of paint, stain and dry wall...and we had to paint all the walls because the baseboards were put in after the carpet...so there was a 1 inch gap, and then patching the concrete and so on. If you were starting with a clean slab it would be way easier. So for 2 rooms we bought 2 bags ferrous sulfate called Copperas, patch and tool and garden sprayer and concrete sealer.. which came to...about $55. (excluding paint and a new fabulous bedspread that was on clearance) If you have all the tools that's more money saved.
Step 1: get everything out of the room and rip out carpet and tack strip. Remove baseboards if you can't live with the gap. (if there is one) If there isn't a gap...tape the baseboards with painters tape because the ferrous sulfate will "grey" the wood.
Step 2: scrap up any paint, drywall...etc off of floor. We started with an razor blade the get off varnish and then switched to hot water and industrial steel wool to get off the paint and drywall. We even got up stain...
Step 3: Get the concrete as clean as possible. We used the shop vac, swept, and mopped..
Step 4: Patch any holes in the concrete. We used vinyl patch concrete..which didn't exactly get smooth...but it worked. After it dried we took a drywall mud tool and scrapped any patch that wasn't even with the floor...we then took a towel and cleaned around each hole to get up any patch residue.
Step 5: Prepare the ferrous sulfate. We didn't know how much solution we would need..so we made 2 gallons...(2lbs ferrous sulfate per gallon) which was plenty for a 175 square foot room. Boil 2 gallons of water...add fertilizer...(yeah it's a fertilizer) and stir for about 5 minutes..strain into a bucket. We used a bungee cord to tie an old towel to a bucket and poured through twice. It will separate into rust and greenish water....stir well and pour into sprayer.
Step 6: spray on floor. Use a sweeping motion keeping a wet edge. Put something down if you plan on putting the sprayer down because it will leave a ring if it gets wet. I first used a roller which was a pain in the butt...I was afraid of the sprayer...but quickly switched on the next layers...you let each layer dry completley before adding more. we live in New Mexico where there is no humidity...so it dried in 20 minutes. Oh and don't wear shoes...go barefoot or wear socks. I did 4 layers.
After the 4th layer dried...you must now mop up on all the extra rust...we used hot water and a mop with white vinegar...maybe a cup per gallon...I didn't measure...it took about 4 times to mop everything up...
4th layer and sealing with a high gloss concrete sealer...the sealer darkened the floor to a mixture of dark terracota and chocolate...so beautiful.
It was a lot of work...but it was worth it!