TIPS FOR CREATING BETTER IMPRESSIONS
- How To Get The Best Results From Stamping Concrete -

The Right Mix

1. Mud thats just right: when finishing stamped concrete, you can't have the mix too soft or too hard. It has to be just the right consistency. Too wet and the concrete pull the stamps, leaving suction marks. Too dry and it will not leave any substantial embossment or impression.

2. The concrete mix needs to be workable but not excessively wet, between 4 to 4.5 inch slump. As the season progresses, and the weather gets warm, a decrease in the slump helps to compensate for evaporation. A lower slump can also prevent oozing between stamps.

3. Consistency on every load poured gives you consistent color and texture. As with all concrete, weather and sunlight affect surface hardness, which also affects color and texture. When setting up a job partially in the shade and partially in the sun, try to make it in two pours.

4. For a consistent impression: 4 inches of aggregate base, and the sub grade compaction before placing concrete, help to achieve a more consistent finish and prevent efflorescence.

5. Some detailed stamps require creamier cement; adjust by adding a little color on the top of the cement. Color gives the concrete a slightly fattier surface or a creamier base.

Smoothing Suction Marks

1. The use of a texture roller or lambs wool paint roller to smooth suction marks that can result from stamping wet concrete.

2. Wedged jointing rollers can be used to knock down suction marks, smooth ridges and clean up the joints between the stamp patterns.

Timing

1. Timing is essential in patterned concrete work. Depending on the time of the year, you'll either have to speed up or slow down to achieve a nicer stamped impression.

Tool Selection

1. Another important factor is to know your stamps before you get to the job site. Do a dry run before you pour so you know how these stamps are going to interlock. Be aware that the stamping tools, if left too long on the slab, draw moisture, affecting the color and texture.

2. The tool selection can help you reduce repeats in the pattern. Some stamps, such as the European fan pattern, are designed to be used throughout an entire pour, repeating over and over again. But a visible repeat, in an ashlar slate for example is very undesirable. Label your stamp patterns using letters A, B and C, or different colors as blue, yellow and red. Interchange these different patterns frequently throughout the slab.

Admixtures

1. Avoid unwanted lines by turning patterns in a 45 degree angle. Also banding with a contrasting color or texture will help break up a large field. Borders can also help downplay slight color variations that can result from different pours. Larger stamps can break up noticeable lines that develop on large areas.

2. The use of admixtures can help minimize the problems caused by weather. Accelerators for cold weather, retardants for hot days can buy you the extra time you need in these conditions.

3. Another useful product is an evaporation retarder. Especially in the fall and spring, when the sub grade is still cold, you have windy conditions and a hot sunny day. The cool ground makes the concrete mushy in the bottom, yet the surface is setting up fast from the sun. Now with a little wind you have a real problem. The evaporation retarder is a spray on product in the very early stages of finishing that can help a great deal when we are faced with this situation.

4. Watch out for crusting and surface cracking with high-range water reducers.

Tamping Tips

1. The use of tamping tools allows the use of different amounts of force to address the areas of the slab that have not set up consistently. A tamper is also a great tool to remove footprints. Tamping tools can range from the standard square 10x10 inch, to a thin 8 inch round piece made out of plywood, when you don't want to leave an outside impression.

2. When dealing with different elevations, or when the slab roll up and down, a 2x10 or 2x12 pieces of lumber can be used to seat the stamping mats. When the concrete is very fresh, lay the mats out, keeping them as tight as possible, then instead of stepping on the mats, lay a strip of lumber down and walk on that, distributing the weight more evenly.

Control Joints

1. Let's face it. Concrete is going to crack. But controlling those cracks with properly designed control joints to aesthetically enhance the slab is the key for a successful job.

2. Joints are pre-planned cracks, which primary job is to break up the slab into geometric patterns to cause it to crack in a uniform way. The whole trick is to fool the eye into seeing beauty, not imperfection. You can use the joints as part of the decoration. The more you carve it up, the fewer the random cracks. But fashion should never take a back seat to function. Joints perform a vital function in concrete work. You don't tell concrete what to do, it tells you what to do.

3. Plan your joints before the pour, and then incorporate a pattern into it. You may score or saw cut joints, add a colored seal, or use a grooving technique to distress harsh lines.

4. Another trick is to incorporate metal as brass, copper and stainless steel as joints components. It's strictly for aesthetics, but it's still functional.

5. Hide control joints by incorporating them into the design with complementary bands and borders.

Pigmenting Liquid Release

1. Liquid release agent is quickly becoming the obvious choice when you have a demand for quicker turnaround, cleaner jobsites, and environmental concerns.

2. The most common way to achieve color highlights is to add an oxide pigment directly to the liquid release before the texturing process begins. Adding a powdered release agent in small amounts is a clean and simple way to achieve this goal. This way the liquid release acts as carrier for the powdered color, which is already formulated and easy to use. Depending on the size of the project, consider mixing the pigment in the liquid release that will cover the whole area to achieve uniformity.

3. Apply the liquid release to the stamping tools and to the concrete surface with a low pressure sprayer and set it to a fine mist so you will avoid over-apply. Keep on moving the stamps as normal. As you move the texturing tools, you'll find that some of the pigment will lift with the stamps. Compensate this by misting the liquid release lightly over the already textured areas to even out the highlighting. After the texturing process has been completed, apply a touch up coat as needed.

4. As the liquid puddles it should carry the pigment into the relief areas of the texture and the joints, where you want the highlighting. The liquid release should evaporate within 12-24 hours, depending on the ambient temperature, leaving the pigment added on the surface.

Mixing Tips:

• Make sure that you mix the dry pigment thoroughly before adding the solution to the sprayer.
• Test your sprayer off the slab to ensure color dispersion
• Continue to shake your sprayer from time to time to keep the pigment suspended.
• Always start with a light solution. Darken as necessary.
• Do your detail and touch up work, before you re-apply.
• Prepare samples using this method whenever is possible
• Use caution not to begin stamping too wet, as impacting of the release may occur.

Step-by-Step Stamping Process
Stamped Concrete Patterns & Colors