You roughen such a floor by etching it with muriatic acid.
Acid wash concrete floor before painting.
Research what cleaning products react with the kind of acid you ll be using and plan ahead.
Clear all loose grit grime and debris from the concrete.
These materials absorb excess oil remarkably well.
However etching or washing concrete with acid opens the pores of the concrete and prepares the surface to accept its next treatment.
Cover grease stains with a layer of sawdust or cat litter.
Even if you rinse the floor with water the cleaning products you use may leave residues that will react with the acid in dangerous ways.
An acid wash is not recommended before applying a stain.
I want to paint the floor.
I ve looked at several sites on how to do this and they all say to acid wash the floor before painting but it seems that they assume there is oil on the floor.
Acid washing is dangerous for people plants and metal objects especially indoors where fumes can concentrate.
Shot blasting and acid etching are the two methods commonly used to prepare the surface for painting.
Etching the surface of the floor opens the pores in the concrete again to improve the paint adhering to the concrete especially on smooth glossy surfaces that may repel the paint.
A smooth concrete floor must be roughened before paint will stick to it.
It also reduces the surface alkalinity of the concrete that can cause some paints to adhere poorly.
Leave the sawdust or cat litter on the floor for at least one day.
If you are planning to acid wash near asphalt drywall or tarmac then it is important to create a barrier.
Step 2 create a barrier.
Before you power wash or paint seal your garage floor you ll want to attack any oil grease or rust spots.
Concrete that hasn t been treated in any way after being poured can be too hard and smooth to accept paint or protective sealants.
Thoroughly clean concrete floors before painting using a heavy duty cleaning solution.
Do not confuse this process with acid staining which colors the concrete.
Muriatic acid acts like liquid sandpaper by roughening the surface of the concrete.
Muriatic acid can work wonders on filthy concrete and it can also be very useful in cleaning excess smears of dried mortar and grout or when attempting to alleviate tough rust stains.
