View Full Version : Rejuvenating concrete shop floor

08-18-2010, 11:03 AM
As some of you know, I'm renovating a 1905 blacksmith shop to house my shop. The building has been used for multiple businesses since construction. Prior to my purchase of the structure, it was used by the local co-op as an oil drum storage facilty. As with any warehousing operation, there is bound to be some accidental breakage or spilling of material. Over a 30 year period, plenty of oil and grease was spilled either through leaking drums or careless workers. As a result, I have a concrete floor with heavy oil stains and dried oil residue.

I'm looking for a good clean way to remove the dried oil residue from the floor. We plan to paint it with an epoxy paint once cleaned up. Has anyone else had a similar issue and how did you solve it?


08-18-2010, 11:14 AM
Open all the doors and put large fans in the doors to move the air through the shop. Buy 5 gals of mineral spirits, real mineral spirits not the crap some stores sell. Buy 4 or 5 bags of floor dry, spread the mineral spirits over a 6'x6' area and with a very stiff broom sweep the floor to loosen and help soak the mineral spirits in and add more mineral spirits as needed. Then cover the area with a layer of floor dry so no wet spots show through and leave it over night.

You can do several areas at the same time but don't over do it. It takes several hours maybe 6 or 8 to soak it up. Sometimes you can reuse the floor dry several times depending on how oily the floor is.

I have even used gasoline on very oily greasy areas. I also use a floor scraper to get built up grease and dirt off first.

It's important to turn off any pilot lights or open flames in the shop and have good ventilation.

The first business I owned had been a blacksmith shop, a tractor shop and a Model T Ford dealership in it's history since around 1900 and the floor had areas with 1" of dirt, grease and oil on it. The floor was like a gently rolling farm. Not all of it, just some areas had deep deposits.

08-18-2010, 12:26 PM
Similar to Carl's way but a little different. I would open things up and spray the floor with Diesel and let it set. Depending on how much or how thick the build up it may need to be scraped and re done. After the concrete is clean but oily I would wet it and sprinkle Tide soap on it and let that soak for a while. Tide is the best readily avaliable soap. The old caustic soap used in steam cleaners is better but hard to come by. Rinse, squeege, and mop until clean.

With that said one off the wall technique would be to rent a floor sander and/or a commercial wax poilisher and clean the floor with that.

I have seen a company cleaning the parking lot at Wal Mart with a portable steam cleaner. There might be such a service in your area. A steam cleaner with caustic soap is the best for cleaning oily surfaces.

08-18-2010, 12:34 PM
The last thing I would want to do is soak my floor in MORE nasty chemicals.

I would either steam clean, or better, sandblast the whole thing first.

I was just working on a jobsite last year where they sandblasted about 200,000 sq feet of concrete- gives it a nice tooth, cleans up most everything, and your epoxy will stick better.

They even sandblasted after we drove a forklift on the floor, to get rid of tire marks. And back charged me for it...

After that I wrapped all my forklift and manlift tires in silver duct tape. Cheaper than paying general contractors to sandblast.

Anyway- you can buy a cheap sandblaster at harbor freight, rent a big compressor for a couple of days, and blast it to a nice clean matte finish.

08-18-2010, 12:58 PM
I had a bad experience with painting my shop floor with epoxy paint. I originally painted my shop with 2-part epoxy, had to wear a gas mask. It looked terrific but after about 5 years it had chipped in several places plus I had built a large addition onto my shop so I wanted to repaint it in preparation for painting the new shop floor. I cleared my shop, cleaned the floor meticulously, sanded it until it was rough, completely removed all dust, and followed the manufacturer's directions when applying the paint. When the paint dried, I eagerly went down and looked at it. Uh-oh. Blisters. Lots and lots of blisters. Horrified, having spent a week to refinish my floor, I gave up on epoxy paint forever.

If I had to do it again I would use good quality floor enamel. You can paint over it easily.


08-18-2010, 01:04 PM
You might consider Trisodium Phosphate in warm water. It is sold as a paint surface prep under the tradename of "liquid sandpaper." You can usually buy it at paint stores or HD or Lowes, as a pure chemical. Dissolve it in water, about one cup per gallon, and scrub the floor with a stiff broom. It is very alkaline and will, given time, take the skin off your hands. Wear rubber gloves and take reasonable precautions; it is not THAT hazardous and it does a very good job of removing grease and oil.

08-18-2010, 02:08 PM
I hate to say it, but you might be reaching for the stars. You have a floor with decades of abuse and oil (and whatever else) that has penetrated deeply into the concrete. If it isn't 110% perfectly clean, the paint will peel or blister. Regardless, it will chip any time you drag something heavy across it or drop something. I have used enamel floor paint with success but in a low traffic area but I've decided against paint in my shop so I don't have to baby the floor.

08-18-2010, 03:21 PM
Oil doesn't usually penetrate too deeply into concrete, unless it's so poor it should be removed and re-cast anyway. You could rent a floor grinder/planer and take the surface off then apply a self-levelling compound or screed topping then paint it.

08-18-2010, 03:32 PM
Load the TSP into the pressure washer and blast away!

Mad Scientist
08-18-2010, 04:01 PM
Use any or all of the above suggestions then wash with a detergent to get rid of any remaining oil film, followed by a muriatic acid rinse to etch the concrete.

08-18-2010, 04:26 PM
Sawdust works perfect. The finer the better. Grinding dust from wood is perfect. Spread it on the floor and wait a week. You'll be astonished how clean your floor is afterwards. And even better, you get the dust for free!

To por diesel onto the floor is the nominee for "Most stupid tip of the year".


08-18-2010, 04:43 PM
To clean the floor I would recommend one of the very strong commercial detergents available instead of mineral spirits, gasoline or diesel. Not that these methods won't work but having experience as a firefighter for many years I believe it presents too much of a hazard, not only by fire but through inhalation. The home national chain improvement stores in my area carry detergents that are extremely strong and should do the job if use right out of the jug.
Regarding the epoxy coatings, I have mixed feelings. Epoxy coatings were applied to the floors in my Fire House twice, once when the floors were new and once later after the epoxy began coming up in large pieces. The areas most affected were the areas where the apparatus parked and it appeared that the hot tires added to the problem because it was especially bad where the tires stopped after calls. Sand blasting, as mentioned by a Ries, may prevent this, I can't say.

08-18-2010, 05:02 PM
If you want a 2K coating, you simply can't do it without shot blasting the floor first. That's why professional coatings are expensive.

I recently laid a wooden floor in my shop. 22 mm thick, it will outlast me. Easy to repair, wood is oiled, so if I spill oil it will only get better. :-)

Looks like this (http://www.laminat-und-parkett.de/product_info.php/products_id/656), only wood is pine.


Forrest Addy
08-18-2010, 05:03 PM
I suggest you use the solvent/floor dry first to get what you can from the pores in the floor. Follow with a cautic scrub wrinsing thoroughly.

Once the floor is clean, do a phosphoric acid etch using a pump sprayer. This may expose aggregate.

Any cracks should be immobilized. Bridge the cracks by trenching to half the slab thickness on 1 ft centers and grout in 1 ft length of re-bar, filling the cracks as you go.

At this point you may wish to survey the floor for soil subsidence. Drag a short length of heavy chain across the floor. If there is no support the floor will sound hollow there. Here you will have to make the decision to pump the slab to ensure full floor support. Look in the yellow pages.

Penultimately, apply a cementatious top dressing. There are some on the market that are very adherant and cure hard but you'll have to research them.

Once the floor is clean flat and dry you can move on to the the floor coating of your choice. If all previou has been successful your finished floor will look glass flat and .

As wth any paint job the prep is 90% of its success - even with concrete floors. The above is expensive and a lot of hard work but the finished product will be superb. You could eat off it, ball room dance, perform surgery, dissect the space shuttle, intall a praticle accellerator, build a clean room, anything where a very smooth easy to clean floor is required.

08-18-2010, 05:05 PM
Long time Lurker, First Time Poster. The best way I've found to clean oil and grease from concrete is to use "Oil Dry" or "Kitty Litter," then make a scrubber from a broom handle and a 9" or so length of 2x4. Drill a hole at about a 45 degree angle in the 4" face of the 2x4 big enough for the broom handle and secure it with a wood screw. Spread the "Kitty Litter" on a section of the floor and use the 2x4 to scrub the grit into the oil or grease. I've found the best technique is to rock the 2x4 back slightly to apply a little more pressure. The "Kitty Litter" is very abrasive and will quickly grind off the old oil and grease, and it's natural liquid absorbency will soak up any liquid left. I've used this method for years in several garages.

08-18-2010, 05:44 PM
Floor dry, Kitty litter or saw dust alone will not take heavy built up dirt, grease and oil off the floor. You can use a strong commercial detergent, mineral spirits or kerosene to loosen and dissolve the oils and the floor dry will absorb them. It may take doing it twice but the floor will come out white like new concrete.

When I used the mineral spirits and floor dry I was amazed at how white and clean the floor came out. The trick is to scrub the floor with a stiff broom while the floor is covered with the mineral spirits and I mean COVERED heavily and scrubbed hard. The thick layer of floor dry is what takes the oil out of the floor and it takes several hours to do it.

This advise is first hand and it worked wonders for the 70 year build up of dirt, grease and oil on the floor.

Forrest Addy
08-18-2010, 07:54 PM
Carl's right. I've used the kitty litter and solvent technique on acres of floor over the years. It works good but it takes time and it's hard work.

Sometimes you have to bite the bullet and work the job. Sweat does not kill.

08-18-2010, 11:47 PM
a straightened mortar hoe for scraping the thicker areas followed by a solvent soak and stiff brush and then a strong soap and more brushing. i cleaned the floor of an old mechanics shop where the oil drips were so thick a creeper would get stuck in the summer. got the crud off the top but never got the stain out. use the summers heat to your advantage,dont wait till dead of winter when the oil is cold and stiffer.

08-19-2010, 12:42 AM
I don't mind the hard work. We've been busy reinforcing the framing with new 2x6's and also some new concrete for some sections. I like the idea of using a heavy detergent or mineral spirits followed by floor dry. Still researching but will start the project early next week if not this weekend.

We have plenty of ventilation and several high power fans that can be located quite a safe distance from whatever chemical or petroleum product we go with.

Good tips all!

08-19-2010, 12:52 AM
Sawdust works perfect. The finer the better. Grinding dust from wood is perfect. Spread it on the floor and wait a week. You'll be astonished how clean your floor is afterwards. And even better, you get the dust for free!

To por diesel onto the floor is the nominee for "Most stupid tip of the year".

I appreciate your nomination but don't knock it until you have tried it. No on second thought I don't appreciated being called stupid. If the floor is caked with oil based crud the diesel is safer, more effective/agressive solvent that is cost effective. You need to have your head screwed on straight when working with any of this stuff. I have also tried the microbe type degreasers that eat the hydrocarbons and digest them. They don't work fast, you have to keep them wet for them to work. With a heavy grease oil build up the concrete will rot before sawdust absorbs the grease if you don't use something to liquify or emulsfy it. A mixture of diesel and the old emulsifier Gunk was the best but I don't think Gunk is avaliable any longer.

Rich Carlstedt
08-19-2010, 12:55 AM
We refinished industrial floors that were heavily soaked in Oil and crud by using a product called OAKITE
This is a very caustic material that is put down with hot water and then scrubbed, and then wet vacuumed.
No gassing or flame hazard.
Rinse and the floor is white !

Check it out..awesome

Rich Carlstedt
08-19-2010, 01:04 AM
I just Googled it and go here to see the spec sheet


The floors become like hospital floors, white and clean

08-19-2010, 01:32 AM
Scrape the floor then use a cleaner like TSP or Zep.
http://www.princessauto.com/components/com_virtuemart/shop_image/product/8158677.jpg http://www.homedepot.ca/wcsstore/HomeDepotCanada/images/catalog/15964.021709008371_4.jpg

08-19-2010, 05:07 AM
If the floor is caked with oil based crud the diesel is safer, more effective/agressive solvent that is cost effective.

Maybe it always missed that. But after an oil spill due to an accident, I never saw the fire department try to clean it with diesel. They used oil binder, cement, silica. They do not use sawdust, because it is blown away. Not the case in a shop. The principle of binders is to have a huge surface. That's what you have with sawdust.
You can use diesel if you want the smell to last for years. Its a low viscous liquid that will only thin down the crud and serve better penetration deeper into the concrete.


08-19-2010, 08:19 AM
How Teknowledgy has changed our lives. My copy of "Machineries" tells me to use oil as a basis for a dusting prevention coating on concrete floors.

Regards Ian.

08-19-2010, 08:29 AM
Hey Terry,

Used to paint ciment pools. If you are planning on painting your floor, DO NOT USE TSP. Trust me on this. If you are only cleaning the floor and are not painting it then go ahead. Great product, wear gloves, safety glasses, etc, but it does not evaporate, it dries out, leaving the chemical behind. Paint over it and the water from the paint, or epoxy will re-activate it and it will peel down the road. What a pain.

Muriatic acid. Good, but not my first choice. It should be diluted as well. 4-1 is what i would start with. (ADD THE MURIATIC ACID TO THE WATER) Mop on and then rince off. OH and then Rince. Don't forget to rince :) . Wear gloves, safety glasses, mask <-- important (even with your fans running), etc.

Ciment is pourous. It will have absorded the oil and may take a long time before those area are dry enough to paint. They will look clean, but will have oil embeded in them.

For the cleaning. Industiral cleaners and a pressure washer is what i would use. Some industrial cleaners have a rince that you use after the cleaning is done. That is good as it neutralizes the chemical after you have cleaned everything. Important if you are going to paint, even more important if you are alergic. Remember these are chemicals...you never know who, or when they can affect a person.

Good luck and post pictures...sounds like you have been busy.

08-20-2010, 08:58 PM
Hey Spkrman,

Thanks for the tips on the TSP. Probably saved me from some big headaches. We do have a pressure washer available so may that would be the better way to go or start with diesel, sop it up with 'dry' then pressure wash.


You might be in the center but the Hub of the universe is about 25 miles away..


Thanks again guys!

08-20-2010, 10:38 PM
I have a cement floor in my shop to be, and I have heard that painting it with Thompsons water seal is a good way to stop dust. I don't think I want a "painted" surface, as it gets pretty slick when wet, and adding sand or something just makes it tougher to keep reasonably clean. Epoxy floors are nice, but good ones are expensive and cheap ones aren't worth the time and effort. I have heard about the water seal and it sounds like maybe a good way to go,, any comments??


08-21-2010, 12:25 AM
Be careful if using solvents. A few years back I saw a guy have the brainwave of cleaning his shop floor with petrol (gasoline). Being heavier than air the vapours sat there until he came back to inspect his handiwork. It was enough to stir up the vapours enough to reach a pilot light in an adjacent gas heater and he blew himself and the shop up!

I've tried pressure washing oil straight off concrete, both with and without detergents, and haven't had much success. You'll always see the oil sheen on top of the water running away regardless of how long you hit spots. The closest I've got is to use a degreaser first to break down the oil, then hit it with the water/detergent. I guess it depends on just how clean you want it? I think if it needs to look pristine as others have mentioned you're going to either need to abrade the surface off, or put something else on top, preferably something that doesn't require strong adhesion to perform its function (eg wood as Nick said, lino tiles etc etc just depending on how you're going to use the shop).