Decorative Concrete Resource Center

Concrete Dyes vs  Acid Stains

Which are better, stains or dyes? That’s the million dollar question.  The answer is “neither”  both are great and effective in achieving beautiful stained surfaces.   The chemical makeup is what makes them different. Acid Stains are a mixture of water, salts and acid that are applied to the concrete surface. They react chemically with the mineral content and excess lime of the concrete surface for a permanent stain. Acid stains are UV stable when sealed and can be used on both interior and exterior applications. Green and blue stains are for interior use only. Acid stains create a variegated or mottled appearance that is unique to each slab. The depth of this colors penetration  ranges from 1/16 to 1/32 of an inch. Exterior concrete surfaces may not color as well as interior surfaces because the environment has leached or percolated out the mineral content. Exposed aggregate (rocks) in worn concrete will not accept staining.

On the other hand Concrete Dyes are a translucent solution, usually based in alcohol or solvent and formulated using very fine particles of color designed to penetrate and color interior or exterior concrete surfaces, including polished concrete.( some dyes are UV stable ) Concrete Dye creates a unique, multi-colored translucent color scheme that unlike paints, will not crack, chip, or peel. Concrete Dyes come in many different colors and can be combined to create an unlimited color palate that creates a similar mottling or marbleized effect as acid stains. Exposed aggregate (rocks) in worn concrete will accept color to varying degrees.

Concrete Dyes and Acid Stains can be used in conjunction with each other. Some manufactures recommend having a corresponding dye available when staining to dye areas that may not take acid stain well. Using dyes together with stains in this application lends to a more consistent and uniform color in the floor.  Dyes and stains can be used to accent each other, increasing the color pallet that is limited by acid stains alone.

There are some down sides to both type stains.  Acid stains are very dependent on the concrete and the reaction that is achieved upon application and have a limited color pallet .  High levels of fly ash effects the color adversely.  Acid staining is not a good candidate for concrete that has been sealed.  Often times it is recommended that the surface be mechanically abraded to help remove the seal. This does help. However, it also removes the fines that the acid stain needs to react with to achieve the desired color. Most often the colors come out muted and much lighter than expected.  Also acid staining is a very wet application if done correctly and is not always a good fit for every application.  In saying that, Concrete dyes also have some down sides as well.  Concrete dyes penetrate very fast and leave little room for error when applying.  The porosity of the concrete plays a large part in the penetration especially when using solvent based dyes.  A surface that is very porous can have what we call “Color Fallout”.  This is where due to the small molecular size of the dye as it may penetrate to far into the slab and you lose the color all together. Typically densification of the slab and reapplication will fix this issue. On the other hand’  If a slab is to tight  the stain may sit on the surface  and not penetrate enough causing the stain to rub off during the cleaning phase of application. A simple fix is a light acid wash or abrading the surface to open up the slab and a reapplication of dye will correct these issues.

No matter what type of stain that is chosen, if the correct procedures and precautions are taken they will both yield very beautiful floors that will last.  The Decorative Concrete Resource Center recommends that the decorative concrete contractor work closely with the Owners, Designers, and Architect to make sure that the right materials or combination of material are used.  

Contributed by Trevor Barnett.  Trevor is the owner of The Nikka Corporation and  Decorative Concrete Resource Center. Trevor has applied acid stains for over 13 years from LM Scofield, Brickform, QC Construction Products, Kemiko, Perma Pro, ArtCrete, Symons/ Dayton Superior, Specialty Concrete Products, Elite Crete,