The basics of concrete finishing tools and how to use them can be broken up into four overarching categories:
- Bull Float & Darby
- Hand Float
- Finishing Trowel
3. Crack Prevention
4. Final Touches
- Concrete Broom
- Concrete Stamps
Each category has their own purpose that points you toward the end goal; but one thing remains constant—timing. It’s knowing when to use the tools that makes the difference between a DIY or “did you hire a professional?” quality finish.
Leveling is the first step toward finishing a slab of any size. The goal of this process is to cut high spots and fill voids left behind during the pour until the surface of the concrete is level with the top of the form boards for a uniform slab depth.
What: A Screed, simply put, is a straight edge used to level concrete. This can be a leftover 2 x 4 or a lightweight aluminum Screed that spans the width of your slab to easily cut high spots and fill voids.
When: Screeding can take place almost as soon as the concrete hits the subbase. You can either screed in sections as your pour or wait until the forms are filled, though the latter works best for smaller slabs. However, most professionals recommend screeding in sections regardless of slab size to ensure more consistent results.
How: Rest the Screed on the top of your forms. The forms then become both a support and a guide as you work the Screed down the length of the slab in a back-and-forth sawing motion. Remember, you're skimming the Screed over the surface, smoothing out the lumps and bumps while excess material fills the low spots.
The key to using a Screed properly is to avoid letting it sink down into the wet concrete. Doing so would create a large void you would need to fill with even more concrete, which means extra work on your end.
If you notice any voids too deep for the Screed to fill completely, grab a handful of excess concrete and toss it onto the void. Then, screed over the area again to level it.
Repeat this process until you’ve screeded the entire length of your slab.
2. Bull Floats and Darbies
What: Bull Floats and Darbies are finishing tools designed to push down aggregate present within the concrete mix while bringing the cream, or paste, to the surface. They also help to level any remaining surface imperfections. While they perform the same function, the difference in use boils down to where they can be used. Darbies are handheld tools with a long blade that are ideal for leveling the edge of a slab. If your slab is small enough (approx. 4ft. max width at any length), you can use this tool over the whole surface; although it is easier to use a Bull Float to get the job done quickly. Conversely, Bull Floats are attached to 72" push-button style handles that allow you to easily level the bulk of a slab, but it is not good for edge work.
When: Bull Floating or Darbying should take place immediately after screeding while the concrete is still wet.
How: You do not want a Bull Float to go over the edges of the form. This can cause gouging around the edge of the slab that weakens the surface, allowing the concrete to chip or crack over time. Always set a Bull Float on concrete only, then begin floating by pushing the tool forward until you’ve either exhausted the length of the handle or you’ve spanned the width of the slab, then pull it back towards you. Repeat this motion across the entire slab. If you do go over the edge of the forms with a Bull Float, you can use a Darby to fix any imperfections that action caused.
Use a Darby by working along the edges of a slab using long, sweeping motions.
It is crucial to not excessively Bull Float or Darby concrete. Doing so works “bleed water" into the concrete. Bleed water is the water that’s pressed up to the surface as the aggregate sinks and settles near the bottom of the slab. Working too much bleed water into the concrete can make your slab weaker, so about two to three passes is enough to get the job done.
Don’t worry if the concrete doesn’t look perfect just yet. Any remaining blemishes will be taken care of during the smoothing process.
The smoothing process aims to make the surface as flat as possible for a stronger, more aesthetically pleasing overall finish; but it’s crucial to know when to start this step.
Unlike Screeding and Bull Floating, the concrete needs time to set before you can start the smoothing process. This means that you need to wait for the bleed water to evaporate. You’ll know most of the bleed water has evaporated from the slab when it loses the glossy sheen of wet concrete.
It is crucial to allow the bleed water to evaporate on its own. Working it into the concrete will weaken the surface, resulting in unsightly cracks as water and air try to escape.
Another way to check if your slab is ready for the smoothing process is by pushing your finger into the concrete. If your finger sinks into the slab up to the first knuckle, the concrete is too wet. Let the slab dry and firm up until you’re only able to press the palm of your hand about ¼” to ⅜” into the concrete.
1. Hand Float
What: Hand floating the surface of the concrete is simultaneously consolidating the aggregate, pulling cream to the surface, and cutting the mud to exactly the right height in one process. It also works to remove imperfections to provide a flatter surface.
There are three distinct types of Hand Float blade materials that all serve a specific purpose during the finishing process:
1. Wood Floats are typically used for going around the perimeter of the slab to consolidate the aggregates present within the mix. These Floats also leave the surface torn, or open, to allow bleed water to evaporate without sealing the concrete.
2. Resin (or Composite) Floats are a cross between Wood and Magnesium Hand Floats. Like a Wood Float, this tool won’t seal the concrete, but it will smooth the surface quite nicely, much like a Magnesium Float.
3. Magnesium Floats are used for concrete mixes that have air-entraining properties. And, as long as they aren’t used too soon, Magnesium Floats can be effective on all varieties of concrete.
When: Only start Hand Floating concrete when pressing the palm of your hand into the surface leaves an indentation between ¼” to ⅜”.
How: Hold the Hand Float at a shallow angle, not flat, up to 45-degrees to prevent the tool from gouging the concrete as you run the tool over the surface. The goal of hand floating is to bring the cream back onto the surface so the Concrete Broom (used in Final Touches) has something to work with.
You can use a variety of movements to achieve this. Try arcs, sweeping motions, or simply run the tool back and forth to smooth the concrete. However, be sure to work using light pressure. Pressing too hard can leave indentations or gouges.
If you’re in a pinch, or if you’re struggling to float the perimeter of your slab, Darbies can behave like extra-long Hand Floats.
2. Finishing Trowel
What: Even though they look like Hand Floats, Finishing Trowels feature large, flat, rectangular blades specially designed to achieve a perfectly smooth concrete finish that is ideal for interior concrete projects.
Finishing Trowels are also available with fully rounded blades that reduce the risk of accidentally gouging the concrete or a pointed design for finishing corners and other tight, hard to reach areas for a consistent finish.
When: Use a Finishing Trowel after floating the concrete or when your palm leaves behind an indentation no deeper than ⅛”.
How: Like Hand Floats, hold the Finishing Trowel at a shallow angle, not flat, up to 45-degrees to prevent drag and work around the perimeter of the concrete using long, straight, back-and-forth strokes.
If you prefer a smoother finish, allow the concrete to set a while longer before returning for a second or third pass.
When testing the readiness of concrete, you must wear gloves to protect your skin from potential concrete burns. We recommend you use a pair of heavy-duty, chemical resistant, and waterproof gloves.
The Crack Prevention and Smoothing process go hand-in-hand on the jobsite since they happen at the same time. If crack prevention tools cause imperfections on the surface, simply smooth them over again with your smoothing tools.
What: Edgers are tools featuring a wide, flat blade with a radius edge used to round the edges of a concrete slab to prevent it from chipping.
When: This tool can be used after the Smoothing process when the concrete is firm but not solid.
How: Use the forms as a guide and run the tool in long, sweeping strokes along the edges of your slab until the edges are smooth, solid, and straight. Walking Edgers function in much the same way. However, rather than working on your hands and knees, this tool comes with a handle so you can walk behind this Edger to round out the edges of the slab.
Finally, use a Hand Float to float over the marks left behind by the Edger for a seamless finish.
What: Groovers come in many different shapes and sizes, but they all work to create control joints, or grooves, in concrete. As the name implies, control joints control where the concrete cracks. That way, cracks will form within the groove line, leaving the surface of the slab unblemished for years to come.
Like Edgers, these tools come in handheld and handled varieties.
When: This tool can be used either before or after edging the slab.
How: First, either stretch Mason’s Line across the slab or use a Screed as a guiding line. Then, shimmy the Groover into the concrete. Run it back and forth in short increments until the groove meets the opposite side of the slab.
Sometimes Groovers catch on aggregate buried beneath the surface, which can leave behind a divot. Thankfully, this is easily fixed. Simply scoop up any excess cream clinging to the Groover or spilling out from the new control joint, place it over the divot, and use the Groover to smooth it out.
The Final Touches work to make your slab practical and functional. Additionally, this is the time where you can use a broom or concrete stamp to change up the concrete’s entire look to match the vibe you’re looking for in your project.
1. Concrete Broom
What: Concrete Brooms are used to roughen up the surface of the concrete for a non-slip finish without being uncomfortable to walk on with bare feet.
When: Brooming should be done while the concrete is still relatively soft; however, all the bleed water must be evaporated before you broom. Typically, you can broom concrete immediately after the smoothing and crack prevention process.
How: The key to a seamless broom finish is patience and a steady hand.
Set the broom on the farthest end of your slab and pull it straight back, slow and steady, in one continuous motion without stopping or twisting. Repeat until the entire slab is broomed.
If you make a mistake or if you drop or twist the broom, do NOT broom over the area again. Because the concrete is now fairly firm, the mistake will still show through any attempted correction. Instead, use your hand float to bring paste back to the surface and try again.
2. Concrete Stamps (+ Touch-up Wheel)
What: Concrete Stamps are great for those who want to add a bit of visual intrigue to their concrete projects. They come in a variety of patterns to suit any taste. There are brick stamps, slate stamps, natural stone stamps, circle, leaf, and even faux wood grain stamps—pick your poison.
Each pattern style typically has a stiff version for the overall pattern and a flexible mat for edge work and tight areas where a stiff mat would have trouble squeezing into.
When: The best way to check to see if your slab is ready for stamping is to press the palm of your hand into the surface. An indentation between ¼" – ½" is the ideal depth your hand should leave behind. Anything deeper than that should be troweled over and allowed more time to set.
How: Concrete stamping can get complicated. Check out our Decorative Concrete Stamping - DIY with MARSHALLTOWN video for a more in-depth tutorial of the process and proper techniques.
Are you ready to take this knowledge and put it to the test? Try pouring your own concrete slab or, if you're feeling adventurous, try your hand at pouring and installing your own concrete countertops.