Cleaning concrete before acid staining is the most important step. You want to make sure there is nothing on the concrete that will prevent the acid stain from soaking in the concrete.
There are a few tools that you can use to help clean the concrete:
Detergent (nothing that contains acid)
The first thing we do when we clean concrete, is run the floor machine with detergent (typically dawn soap) over the whole surface to remove dry wall mud and any loose paint. This will help you see what is left on the concrete that needs to be removed.
If there is glue that is still on the floor, you might need to use a solvent such as xylene (make sure pilot flames are blown out) to remove it. If there is paint still on the floor, scrape as much of it of as you can, then go over the surface with xylene to remove any stubborn areas. If the whole surface of the concrete floor is painted, you will need to use a chemical stripper or grind the concrete. If you grind the concrete you will have to grind the whole area to make sure the surface texture is all the same. If the paint and glue remain on the concrete floor when acid staining, you will notice them.
After you have removed all the contaminants from the floor, use a mop with clean water to thoroughly clean the floor. Let the concrete completely dry out and then you are ready to acid stain the concrete.
Painting concrete is a great way for DIY’ers to add color to concrete. Most people see painted concrete porches that look very bad because the paint is peeling off from the concrete. This can be easily prevented by taking the necessary steps to prep the concrete floor before applying the concrete paint.
Before you paint the concrete floor you should evaluate the concrete and take notice of any major cracks or spalls in the concrete, and how smooth the surface of the concrete is. If the concrete does not have any cracks or spalls but fells pretty smooth, the concrete should then be acid washed to achieve a concrete profile similar to 80 grit sand paper. Profiling the concrete is the most important step for achieving a successful painting job.
Once you have prepared the concrete floor you can then begin painting the surface. I always like to cut in the edges and then roll the middle section. Putting thinner coats of paint is always better then putting the paint on thick. Thinner coats helps the paint soak into the concrete for better adhesion. Sometimes you can thin the first coat of paint so it will soak into the concrete deeper. Always fallow the manufactures directions, not all products have the same installation directions.
If stained concrete is not maintained properly you will start to get wear patterns in the high traffic areas. As people keep walking on the stained concrete floor it will eventually erode and the stain will get dull. A lot of times these areas can be re-stained depending on:
if there is no remaining sealer on the concrete (if water soaks into the concrete)
if the sealer that was previously used was a solvent based acrylic
When you re-stain concrete you want to use a solvent based dye (if the sealer used was a solvent based). These will actually soak into a sealer if it is a solvent based acrylic sealer. After you have re-stained the concrete floor you will then need to re-apply a coating of sealer.
If you are looking at changing the color of the stained concrete floor completely, and your not sure what type of sealer was used on the stained concrete floor, the best and safest way is to remove the sealer either by grinding the sealer off or using a chemical stripper. Grinding will also remove a lot of the unwanted stain in the concrete giving you a nice clean surface to re-stain the concrete floor.
Grinding concrete involves using an abrasive, mostly diamonds to grind the concrete surface down. There are many different grits (the size of the diamond smaller the number the larger the diamond) that can be used to grind concrete depending on how much of the surface needs to be ground down. You can have concrete ground down inside or outside.
Before you can start staining the concrete floor, you must examine the concrete floor to see if there are any repairs to be made.
If there are any small divots in the concrete you can use a cement patching material to fill in the divot. Beware that these patches will stain different from the surrounding concrete. You can try to match the color of the concrete by adding some tinted grout into the cement patching material.
If you have small cracks (smaller than the thickness of a credit card) the best thing to do is to leave them alone. Filling them with a cement material will make the cracks stand out more. A lot of time the cracks will add to the uniqueness of the stained concrete floor.
Sometimes the concrete floor is in to bad of a condition to be stained and must be either ground down or resurfaced. If cracks are larger than the thickness of a credit card resurfacing the whole floor is the best option. Resurfacing will give you a nice clean surface to apply the concrete stain. Before resurfacing you need to use a crack chasing blade to clean the crack out and then fill the crack with an epoxy crack repair material.
Always make sure to check the cure times on the repair materials. Do not stain the concrete before the materials have fully cured.
Using acid stain by itself to stain concrete will give very cool unusual affects; although, when combining acid stain with miracle grow you will get a very unique speckled look on the concrete. The acid and metallic salts in the acid stain react with the chemicals in the miracle grow and leave a greenish spots on the concrete.
When we use miracle grow to add special affects to an acid stain job, we first sprinkle the green miracle grow powder on the concrete. We then spray the acid stain on the concrete making sure we wet the miracle grow powder. Over the next couple of hours the acid stain will start to react with the concrete and the miracle grow, you will notice where the miracle grow was sitting on the concrete will start to turn a whitish green color. After neutralizing and sealing the concrete you will see the green speckles on the concrete.
Here is a close up of a concrete floor stained with an acid stain and miracle grow, the green in the concrete is from the miracle grow.
For more information please visit are website at MVL Concrete.