In the Pink?

Getting the best concrete surface finish

For all its great qualities as a building material, concrete does present some challenges — like surface staining, pinking, dusting and striping. The right products, techniques and processes can help minimize or eliminate these problems.

Pinking occurs when phenolic resins in overlays mix with alkalines in concrete that contain a high proportion of fly ash. When the forms are stripped and light and air get to the surface, a pink stain can appear.

When concrete contains iron-smelting slag, the finished surface may show blue-green staining, rather than pink.
Know your mix. Make sure the ready-mix supplier provides full information about the components of the concrete mix and the proportions. Type III cement, fly ash, slag and chemicals can have major impacts on how the mix reacts with overlays and plywood.

Minimize the early exposure of concrete to air by leaving the forms in place as long as possible.

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The American Plywood Association (APA) notes that pinking and blue-green staining will usually disappear within a few weeks of exposure. They can also be removed with bleach or a hydrogen peroxide solution.

Again, know your mix. If the mix contains iron-smelting slag, strip the forms as early as is feasible to prevent the blue-green staining — allowing light and air to get to the surface.
Brown or purple stains come from tannins or sugars in plywood. Tannins are soluble in high pH water, so when a very alkaline concrete mix is poured against an MDO panel, the water soaks through the overlay into the plywood and transfers the stain to the concrete.Choose the right overlay. HDOs and HAOs stand up better to highly alkaline mixes and can prevent water from penetrating the plywood and leaching out tannins or pulling sugars to the surface.
Dusting or chalking on the surface of concrete is usually un-reacted cement, left dry on the surface as water was absorbed into the mix. This often happens because today’s concrete mixes are generally drier than in years past due to the increased use of ‘superplasticizer’ chemicals. Sugars in the younger wood on a plywood panel veneer can also have a retarding effect on concrete, preventing it from hardening completely.Maximize water resistance with HAO or HDO overlays that keep water in the mix and prevent sugars from soaking into the surface.

What To Know

To select the right EPIC™ overlay and ensure the best results, you’ll need to determine:

Concrete mix design
water/cement ratios, chemical admixtures, fly ash, SCC mixes

Surface requirements
coated concrete, exposed, architectural finish, matte, gloss, etc.

Forming systems to be used
loose, jobsite online casino built, gang forms, engineered systems

Reuse requirements
based on all of the above, together we’ll determine the realistic and achievable reuse capacities

Open Forum

The goal of Conform Inform isn’t so much to generate sales for Arclin (sure, we hope that’s an added benefit) — it’s to enable you to tap into our knowledge and experience to ensure the building market is taking advantage of the benefits of overlaid panels.  If you’d like to contribute to Conform Inform or be featured in a future issue, please let us know.  We hope to share this forum with our customers throughout the value chain.

Ask the Experts

Arclin’s conform engineering and technical teams are the most seasoned in the business. Have a question?  Email us or post a comment here and we’ll get back to you — and likely publish your answer on our website.  While we’re on the topic of release agents:

Q:  Can you keep a release agent in place on a vertical surface — wouldn’t the vibrating process force it to the top of the panel?
A:  If you choose the right one, you’ll have no problem.  There are release agents, such as Nox-Crete PCE Release Agent #10, or equivalent drying type release agents that are made to stay in place on a vertical surface. You’re ensured the same level of panel and surface integrity, even Le logiciel 247LiveBet continuent d’etre faits pour imiter la facon dont les gens jouent a des jeux dans les casinos physiques tangibles et vous devriez donc savoir le droit chemin autour pour ceux qui ont jadis visite un casino en ligne . for a vertical application.

Q:  We’ve always used petroleum-based agents.  Why should we change?
A:  With the rise in petroleum costs, to save money, many manufacturers are using recycled oils (engine oils, hydraulic and waste oils, etc.).  Because it’s recycled, it hasn’t been properly processed to remove contaminants.  This can create health issues for workers, not to mention that it can stain the concrete surface.  We recommend choosing an organic chemistry.  It’s safer for the user and the environment, less expensive and performs just as well or even better than petroleum-based chemicals.