Concrete Preparation for Staining

After a greuling effort, my concrete slab is pretty darn clean! It was covered in latex paint - splatters all over and also a inch or so thick line around the perimeter where baseboards were previously painted. Glue also abounded - where the vinyl tile was pulled up. There were also wavy lines of glue where the carpet squares once were. On top of all this, there were these odd, black, greasy blobs here and there.

I wasn't sure what products to use to clean up these messes. So I began experimenting with various stripping compounds as well as paint thinner and mechanical methods (scraping, grinding, etc.). After a lot of wasted time and money trying different products, here is what worked for me:

1. Motsenbocker's Stain Lifter #5 - removed latex paint and some glue from concrete. $20 per gallon - order it online at HomeDepot.com. Or you can buy 22 oz bottles in the store for $9. It's biodegradable and water based. Not too fumy but have good ventilation. Works better than more toxic stuff like Klean Strip, Tuff Job, etc. Easy to apply and clean up as it is just a spray - not a nasty, toxic, gel.

2. Bean-E-Doo - very good at removing glue and any mastic material. I used this on the mysterious black blobs and also on the wavy glue lines and vinyl tile glue that didn't come up with Motsenbocker's #5. It's something like $15 per quart so much more expensive than M#5. In Austin, I found this product at a place called the Stain Shop. It's completely soy bean based and has no fumy smell. One downside is it can leave concrete looking darker than it was before - like oil on leather. So try not to leave it sitting for longer than necessary.

3. Tri-Sodium Phosphate - this is more like a detergent used to clean up after my chemicals. Don't rely on it to clean anything hard core off your slab. Mix half a cup or so with 2 gallons of water - get the large box of dried crystals for best economy.

4. Floor Maintainer - this is the big floor buffer like you see your custodian using in grade school to clean the floors. Use the BLACK abrasive pads - the green ones left green residue all over the damn place, which I had to clean! Adjust the inclination of the handle before you start the thing up to about 60 degrees or so - you WILL lose control of the thing if you start it with the handle totally vertical. Push down on the handle to steer it left. Pull up on the handle to steer it right. Expect to crash it into the wall at least once before you get the hang of it - I thought that stuff was overblown but I had a real hard time with it at first. I'm a big burly dude, but I crashed it twice and left some seriously large dents in my drywall... Good thing there is so much other drywall work to do - in the grand scheme of things not much harm done.

4. Rapid Strip grinding wheels - these are odd looking but very effective grinding wheels that you can use on either a drill or an angle grinder. They are fibrous and either blue or black in color. I recommend using the angle grinder as it's easier to position for stripping paint/glue etc. - especially around corners. A drill will work too - but use one with a chord if you have a lot to do because my 18 volt chordless ones kept losing charge. I used this for whatever didn't come up with the big mechanical buffer - and also around edges and corners.

5. Razor Blade Scraper - this is a razor blade mounted on a 6" or 7" handle. It was used where stuff was so thick that it was inefficient to try chemicals or the grinding wheels. Scrape it first with this and then try the above stuff.

My procedure for each room:

1. Remove baseboards and sweep.
2. Use pump sprayer (all plastic) to spray TSP
3. Use mechanical buffer to buff
4. Squeegee water/residue into one puddle and use wet-vac to vacuum up.
5. Once dry, use pump sprayer to apply Motsenbocker's Stain Lifter #5 (I had one with M#5 and one with TSP).
6. Use mechanical buffer to clean.
7. While Mostenbocker's stuff still on there, spray on (or you can use mop to apply) another round of the TSP.
8. Use mechanical buffer to clean the TSP and M#5 combo.
9. Squeegee liquid into a puddle and vacuum up.
10. Whatever did not come up with mechanical buffer, get it with the angle grinder and rapid strip wheel and/or razor blade scraper.
11. After Steps 1-10 were done, I sprayed rooms with TSP one more time and used a bristle brush on a pole (like you use to clean a deck) to agitate/suspend any remaining residue.
12. Squeegee and vacuum residue.
13. Use sponge mop and bucket with TSP solution to do final mop-through.

If I had this to do over, I would probably leave out a few of the TSP applications:

1. Sweep
2. Spray with M#5
3. Buff
4. TSP application
5. Buff
5. Squeegee and vacuum
6. Grinder / Razor Scraper
7. TSP app
8. Brush on a pole
9. Squeegee and vacuum
10. Final mopping with sponge mop

Concerns:

1. I still have some lines on my slab that would not come up with any of this - looks like water got into the carpet and had some reaction with the floor to make rusty lines between carpet squares. Fortunately these are similar to the color of my concrete stain, so I'm hoping they blend in? We'll see.

2. The Bean-E-Doo left some darker areas in my floors - what will those look like after stain application?

3. There are some divets in my slab that need to be filled with masonry. Will that material stain a different color? Should I fill them in or leave them alone?