Concrete walls present a unique problem when it comes to acid stain. Most acid stains available for concrete are the consistency of water. If you try to apply this acid stain to your wall, it won't adhere, but will run down the wall and all over your floor. However, there is a solution if you wish to add depth and color to your concrete wall: gel acid stain. Follow the steps below to achieve a beautiful acid-stained concrete wall.
Things You'll Need
- rubber gloves
- old clothing
- masking tape
- foam brushes
- paint pan
- concrete surface prep products
- baking soda
- pump sprayer
- large sponges
- shop vac
Find a supplier for gel concrete acid stain. If you do an online search, type in 'gel concrete acid stain'. A source for gel concrete acid stain is included in the resources below.
Select your color or colors. Concrete acid stains work by chemically altering the concrete. These acid stains are made from natural minerals. While colors are limited, they do range from rich browns to avacado-like green. You can change the appearance of a particular color by mixing it with another color, overlapping colors or applying a second coat to achieve a darker color. Note, the acid stain won't work on sand or rocks, only cement. If your 'concrete' wall is a mixture of rock and concrete, you may not get the look you desire from acid staining.
Prep the wall. If your wall has been previously waterproofed, you will not be able to use acid stain. If your concrete wall has any sort of residue from paint, varnish or adhesives, you will need to use a paint or adhesive stripper made to remove the residue in question before you apply the stain. Any areas that contain residue with either affect the color of your acid stain or will not accept the acid stain at all if not properly removed.
Prep your work area. Since you are working with an acid that has the potential to damage any surface it comes in contact with, you will want to mask and cover any surrounding surfaces that you want to protect. Floors, wood trim and ceilings near your concrete wall should be covered if you are working indoors. If you are working on a retaining wall outside, you will want to cover the concrete walk beneath the wall if you are not staining this surface as well.
Wear protective clothing. You will need rubber gloves, old work clothes, and goggles to apply gel concrete acid stain. You are working with an acid. It will stain your clothing and it will irritate your skin and eyes if you accidently come in contact with it.
Apply the gel concrete acid stain. The gel stain has the consistence of thick pudding. I find it easier to work with by putting some in a paint tray. Use a foam brush or paint pad to apply the stain. If you are working with one color, apply an even coat over the entire surface. A gallon of gel acid stain will cover from 200 to 300 square feet depending on how porous your wall is. If you are working with two colors, depending on the look you want you can overlap in random patterns to create a 'marble-like' appearance. You can even utilize your creative side to make patterns like diamonds or something more intricate like a sun.
Allow the gel concrete acid stain to cure on the wall according to the package directions. Curing times range from minimums of two to eight hours. If you are working on an outdoor concrete wall, make sure the wall is protected from rain or water during the curing time. As the wall cures, you will notice a flaky, white residue on the wall and the appearance of the colors will change. This is normal.
Neutralize the concrete acid stain. After the curing time has passed, you are ready to neutralize the acid stain with a mixture of baking soda and water. Use one to two tablespoons of baking soda per gallon of water. I used a pump-up sprayer and sprayed the baking soda-water mixture onto the wall, working from top to bottom. I used large sponges to sponge up the mixture as I sprayed so that it didn't run down the wall and compromise the colors below. An assistant used a shop vac to collect any mixture that escaped the sponge. If you are working on an outdoor wall and are not as concerned about the mess, you could simply saturate your concrete wall with the mixture using a sprayer.
Clean the wall. After you neutralize the entire wall, use clean water to wash the entire wall and remove any remaining residue. Use a nylon scrub brush to remove stubborn residue.
Let dry. Let the wall dry completely before sealing. This may take up to twenty-four hours depending on your climate.
Seal the wall. All acid stained concrete needs to be sealed with an appropriate sealer. Sealers are available in a wide variety of formulations depending on the application. If you are sealing an indoor concrete wall, you will want to use a water-based sealer approved for indoor use. I used a wide paint pad to apply the sealer and applied two coats. Let each coat dry thoroughly according to the manufacturer's directions before applying the next coat.
Admire your new acid stained concrete wall! Acid staining a concrete wall is fun and easy to do. Once you master the art of acid staining concrete, you might wish all the walls in your home were concrete!
Tips & Warnings
- Unless you are creating an intricate design, don't worry so much about the finished product. We started out trying to create a certain 'look' and ended up having something that looked like a cowhide. So I went back over the entire wall with the darker gel acid stain to disperse the pattern and create a more haphazard look, which is what I had wanted to achieve.
- Call the manufacturer to inquire about the amount of gel concrete acid stain you will need for your project.
- Many factors, including age of concrete, concrete makeup (whether it includes rocks), residue, etc. will affect your outcome. Call the manufacturer if you have any concerns about your acid staining project.
- You are working with acid. Be very careful to protect your skin, eyes and furniture.
- make sure you are using the proper sealer for both your project and area. Many states have environmental and VOC regulations/restrictions in place regarding the use of solvent-based sealers. If you are sealing indoors, you will want to use a water-based sealer.
- Photo Credit copyright, 2009, Lorna Thomas
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