Q: What causes concrete to show patterns or stains around the edges?
A: These are usually signs that the edges of the panel haven’t been properly sealed. That allows water to seep into the plywood under the overlay and transfer patterns or stains to the concrete. This concrete water absorption can also result in “picture framing” where the perimeter of the form panel will be darker than the The major benefits of such a machine besides the marketability and competitiveness to other slot machines and pure electronic or video games and gaming devices are:(1) Prevention of tampering of the game to create illegal wins and payoffs. center.
To prevent this problem, make sure your conform panels are sealed all around the edges. It’s best to use a quality edge-sealer designed for this application, but even a good quality acrylic paint will help. You should also re-seal scuffed edges and fastener openings between uses.
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Contractors, specifiers continue to use more expensive materials
It seems like a no-brainer: BBOE is more expensive today than conform panels with MDO overlays. MDO panels offer up to twice as many re-uses as the BB panel, give a better-looking finish and can significantly reduce jobsite waste and contribute to LEED credits.
So why then do some contractors continue to use raw BB? In a word, says Jeff Linn, responsible for plywood mills sales for concrete construction chemical manufacturer, Nox-Crete.
The choice of BB is rooted for many in the confidence that comes with dealing with familiar materials and with a lack of understanding among specifiers, architects and contractors of the advantages of overlaid conform panels over BB.
(Further proof of value: Arclin’s Enhanced Flow MDO adds an additional three to five pours to traditional MDO. A quick look at the math proves that one extra pour pays for the cost difference between the panels. And its resistance to alkaline concrete mixes helps the panel last even longer plus creates a better finish.)
So as an industry, how do we combat habits among our downstream product users that are costing them needless time and money and avoiding clear environmental benefits?
In another word: education.
“All of us in this industry can help educate our downstream customers,” says Linn. “We need to collectively provide resources and training so they can better understand the variety of forms available and how to pick the right form for the job at the best value.”
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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.
|SURFACE ISSUE||PREVENTIVE PRACTICE
|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.
Great products just got even better
“Continuous improvement” sounds like a business-school buzzword, but at Arclin, it’s just what we do. We’re always interested in—and excited about— finding ways to make everything we produce even better.
Now, that focus on continuous improvement has led to an evolution in Arclin’s EPIC™ suite of concrete forming overlays.
“We’ve re-engineered our EPIC™ overlays so they offer better performance at every stage, from the panel manufacturing to construction in the field,” says Scot Johnson, Business Director Overlays.
The EPIC™ online casinos suite of conform overlays now features some significant advances:
- MD 3000 resin, which more uniformly saturates the overlay base sheet to form a stronger bond to the panel and stand up to harsh concrete mixes
- New paper, combining wood fibers in new ways to give the EPIC™ overlays the strength and alkalinity resistance needed
- New release coating on EPIC™ Enhanced Flow MDO 4369/4379, to ensure that the overlay releases smoothly from pressing equipment when the panels are being made
Arclin’s new resin blends well with ‘hydrophobes,’ compounds that make the overlay more moisture resistant. That gives the end-user even more pours per panel and a better finish with the new EPIC™ MDO 3333 and the Enhanced Flow 4369 and 4379 overlays.
The EPIC™ evolution is a prime example of Arclin’s constant search to find new applications for chemistry that meet real-world conditions and market demands.
|Product ||Concrete Finish||Common Applications||Description / Attributes||Pours per Panel
|EPIC™ Medium Density Overlay 3333 (MDO)||Matte||For concrete that will be coated, painted and exposed ||Minor grain and no wood characteristic transfer with hardwood face substrate|
Moderate grain and wood characteristic transfer with fir face substrate.
|10 – 15
|EPIC™ Enhanced Flow Medium Density Overlay 4369 (Natural Kraft) and 4379 (Green) (MDO)||Smooth, Matte||For concrete that will be coated, painted and exposed ||Enhanced alkalinity resistance|
Minor grain and no wood characteristic transfer with hardwood face substrate
Moderate grain and wood characteristic transfer with fir face substrate
|10 – 20
|EPIC™ Coated Concrete Form Overlay 4098 (MDO)||Gloss||For architectural finish|
on exposed concrete
|Phenolic film applied to fir-face softwood panel for no wood characteristic transfer||15 – 25
|EPIC™ Natural Kraft 2252/2253 (HDO)||Smooth, Low- & Semi-gloss||Phenolic film applied to fir-face softwood panel for no wood characteristic transfer|
Minor grain and wood characteristic transfer with fir substrate
FSC®-certified, unbleached Kraft paper overlays may contribute to additional LEED credits
Minor grain and wood characteristic transfer with fir substrate
Minor grain and no wood characteristic transfer with hardwood substrate
|15 – 25
|EPIC™ High Alkaline Overlay 2600 (HAO)||Semi gloss/high gloss(based on pressing surface condition)||For “aggressive” high alkaline concrete mix designs||Minor grain and no wood characteristic transfer with hardwood face substrate|
Minor grain and wood characteristic transfer with fir face substrate
|15 – 35