STAINS

Stained concrete has become one of the most popular concrete finishes for new construction and remodeling projects. These applications can be performed on interior concrete slabs and is growing in popularity for exterior concrete. With the use of multiple colors and or score cutting there are limitless possibilities of designs. These designs can also include logos. Your only limitation is your imagination! When completed the result is a translucent marbleized effect which is unique to the staining process.

ChemStone (Acid) Staining:

These chemical treatments transform the concrete color by adding a translucent mottled coloration that produces a unique look whenever it's applied. No two floors or walls look the same after being treated with this material. That is because the stain reacts with the lime in the slab, which is different with each pore. That's the magic of the chemical (acid) staining process. This process should only be performed to concrete which has not been sealed or coated in the past. If it has it can be refinished with our overlay system prior to being stained.

HydroStone (Dye) Staining:

HydroStone is a permanent, penetrating , solvent-based stain available in 20 standard colors to transform residential , commercial or municipal concrete paving into an enchanting, beautiful and vibrant terrain, custom colors are also available. HydoStone works by penetrating and reacting with mineral compounds and/or siliceous materials in concrete to create a translucent or marbled appearance.

Concrete Chemical Staining Facts

Chemical stains can be applied to new or old, plain or colored concrete surfaces. Although they are often called acid stains, acid isn’t the ingredient that colors the concrete. Metallic salts in an acidic, water-based solution react with hydrated lime (calcium hydroxide) in hardened concrete to yield insoluble, colored compounds that become a permanent part of the concrete. Several companies manufacture chemical stains that are variations of three basic color groups: black, brown, and blue-green.

The acid in chemical stains opens the top surface of the concrete, allowing metallic salts to reach the free lime deposits. Water from the stain solution then fuels the reaction, usually for about a month after the stain has been applied. Other factors that affect the outcome include:

  • Cement properties and amount
  • Admixtures used
  • Type of aggregate used
  • Concrete finishing methods
  • Concrete age and moisture content when stain is applied
  • Weather conditions when stain is applied
  • Efflorescence

In general, cements that produce larger amounts of calcium hydroxide during hydration will show more stain color, and higher cement contents pro-duce more intense colors.

Air-entraining or water-reducing admixtures don’t pose a problem. However, calcium-chloride accelerators can cause very mottled, darkened areas, and for this reason aren’t recommended.

Nonchloride accelerators don’t cause this mottling effect.

If they’re near the surface, calcium- based aggregates, such as lime-stone, take stain readily and deepen the color of the concrete above them. Siliceous aggregates, such as gravel, don’t react with the stain.

Open finishes achieved by floating followed by minimal troweling take more stain and produce denser colors than do hard-troweled surfaces. However, open finishes can lose color faster if not properly maintained due to the concrete surface wearing. Colors on troweled surfaces also look richer than those on floated surfaces. But at times requires the surface to be sanded or the use of a higher acid concentration to ensure adequate stain penetration.

Slabs placed in wet weather result in a richer stain color if the concrete is stained soon after it’s placed. However, wet slabs are more likely to effloresce, lightening the color and causing a more mottled effect in areas where the stain doesn’t take because efflorescing salts hinder penetration. On sunny days, the concrete can become hot and dry, and the stains won’t penetrate as deeply into the concrete. 

The continued presence of water can cause the reaction to continue for a long time, and concrete stained blue-green may gradually turn brown or even black. Initially, this provides nice variation to the appearance, but eventually, nearly all the blue-green color may change to brown and black. Because of the possible color shifts, some manufacturers advise against using these colors for exterior concrete. Interior slabs must be placed on a well-drained base or sub-grade and have a low moisture content before stain is applied.

Other factors with the concrete can affect the way stains will or will not react and create color. These not only include the manner in which the concrete has been finish but also include damage that may have happened such as chips and gouges and contamination of the concrete with chemicals that will hinder or prevent the chemical reaction that create the color from happening.

How hard a slab is troweled will affect the color as earlier discussed but the manner of how well or how poorly a slab has been finished will also make a difference. The staining process is a translucent coloring process which will not cover imperfections. In fact it will enhance these imperfections such as chatter marks and add character to the floor.

Metallic particles that have become impregnated into the concrete during the concrete finishing or cutting process will also have an effect on how the stain reacts. These metal particles can cause dark or black areas due to the acid reacting with the metal. Due to this reaction causing black or darker areas metal shavings are used at times to create color effects during the staining process.

Concrete slabs which have had sealers or contaminates on the concrete surface are very unpredictable and should be mechanically stripped and refinished with an overlay. Applying chemical strippers to remove sealers or painted surfaces may look to be completely clear of contaminates but come back to haunt you when the stain is applied. It will cause areas where the stain will not react and create color.  These areas of no color and may not react no matter what is done due to contamination being in the pores of the concrete and preventing the metallic salts from reacting with the free lime deposits.

Another factor that can cause differences in coloration is how the slab cured. If an area was covered during the curing process while another was not this can also cause each area to react differently from each other.

There are many factors that can effect how a slab will react during the chemical staining process; this is what makes each of these floors beautiful, unique and distinctive. You must be open to these possibilities when requesting this floor finishing techniques or this system may not be for you.

Maintenance of stained concrete floors is dependent on how a floor will be used but just as important is the type of sealer that will be chosen to protect the surface. The standard sealer in the industry is an acrylic sealer, either water based or solvent based. Both are fine sealers but the solvent based sealer will bring out richer colors from the slab and offer more durability. If the area is to receive high traffic it would be recommended to use an industrial clear coat such an epoxy or urethane. Each coating has its benefits; our representative will explain each one and which would be recommended. Regardless of which sealer/coating you have chosen to seal the surface with it will need to be maintained. This is a simple process of applying floor finish to a clean surface and allowing it to dry. How often will depend on the amount of foot traffic the floor will receive.

4838 W. 128th Place
Alsip, IL 60803
Office 708-629-0825

info@concreteoverlays.com

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