How To Finish Concrete Smooth
Using A Steel Trowel

One of the best ways you can learn how to finish concrete smooth is by watching me using a steel trowel to finish this small concrete floor. I've been using a mag float and a steel hand trowel to finish concrete smooth for many years.

There's a technique I use when I finish concrete that makes using a mag float and hand trowel a little easier to learn.

Keep in mind, timing is everything when finishing concrete. Starting too soon or too late greatly impacts the final results.

These three videos will help you understand the timing of when to start and the process of troweling concrete smooth.

I'll explain the basics here, then I'll go into a little more detail:

  1. Mag float the concrete first by moving the mag in a back and forth action while applying moderate downward pressure.
  2. After floating the concrete, let it dry for a bit and then steel trowel it.
  3. Slightly tip up one edge of the steel trowel and while pressing downwards on the trowel, move the trowel in the direction of the edge you have tipped upwards.
  4. Make a sweeping motion while troweling, when you move the trowel in the opposite direction, tip the other edge slightly up so that edge doesn't dig into the concrete.
  5. Continue moving the trowel back and forth over the surface of the concrete until you see it smooth out the surface.
  6. Once you've troweled the entire surface, let it dry a bit and repeat this process as many times as necessary to smooth the surface to your desired look.

The basic tools you'll need to hand trowel your concrete smooth are:

In the video below, I go into great detail explaining to you how to finish a concrete floor smooth using just a mag float and steel trowel.

Knowing when to start troweling is always the hardest part of the process for most people.

My guidelines for when to start mag floating and troweling are:

  • Check the firmness of the concrete by pressing into it with your fingers
  • If you can press into the surface 1/2 inch or more, then wait 15 - 30 minutes, then check it again.
  • If you can only press into the surface about 1/4 inch, then the surface is ready to mag float.
  • Always mag float the surface first before troweling.
  • If you steel trowel the concrete too early, you could potentially damage the surface by trapping moisture or air under it - this causes blisters and scaling eventually.
  • After you've mag floated the surface, you may have to let the concrete dry a bit, then you can steel trowel it.

Below is a really good video that teaches you when to start the finishing process of mag floating.

These three videos and my explanation should help you understand how to finish concrete smooth using a hand trowel.

There's a lot of variables involved when it comes to when you start the process, like:

  • how wet or dry you poured the concrete (slump)
  • how hot or cold the air temperature is
  • if your project is in the sun or shade
  • what psi concrete mix you use
  • if you use an accelerator or retarder in the mix
  • if the mix has hot or cold water in it
  • the type of sub-base you're pouring on

If you pour your concrete really wet (or loose) this will greatly extend the amount of time you have to wait to start finishing.

You'll have to wait for almost all that mixing water to evaporate before the concrete will be firm enough to mag float. 

Not to mention, pouring the concrete too wet will weaken the strength of the concrete also.

What's the difference between a mag float and a steel trowel?

How to finish concrete smooth by handSteel Trowel on Left - Mag Float on Right

A mag float (the one on the right) is used when the concrete is first poured to smooth the edges and make wet pads for screeding the concrete.

It is also used for the first pass to smooth the concrete when starting the finishing process.

The mag float helps smooth out concrete when it is softer, it brings a finer cream or paste to the surface and prepares the surface for hand troweling.

The steel trowel (on the left) is used for the 2nd, 3rd, 4th, and final finishing passes. (however many it takes to get your desired result).

There are rounded edge trowels like the one above an square edged ones. Both are good, it's only a preference as to which one you like to use.

When using either the mag float or the steel trowel you have to slightly tip up the edge of the tool in the direction you're moving it.

You also have to exert some downward pressure on each tool to get a smooth result. The amount of downward pressure will be directly related to how soft or hard the concrete is at that time.

After pouring, screeding, and bull floating the concrete there is usually always some bleed water that rises to the surface of the concrete.

Make sure you let this bleed water evaporate before you start mag floating the surface. Floating the bleed water back into the concrete will weaken the surface and may cause scaling or blistering at a later date.

I always mag float the concrete before steel troweling. Mag floating the surface will continue to let the surface "breath" and continue to let moisture escape out the surface.

If you steel trowel the surface too early, you risk "sealing" off the surface and trapping some moisture that is still trying to rise and evaporate out of the concrete.

This trapped moisture is the cause of scaling, blistering, and a weaker wear surface on concrete floors and slabs.

How to Mag Float concrete

In the picture above I'm mag floating the surface after waiting for the bleed water to evaporate but still when the concrete is soft enough to smooth it out and work up a nice cream on the surface.

In the picture below I'm hand troweling the surface after I've mag floated it and let the concrete set up (dry out) a while. 

Each time you hand trowel the surface and let is dry up a bit, it gets smoother. The amount of time in between troweling is what the videos above will help you with.

NOTE: See how I"m tipping up the trowel as I'm moving it to the left. The angle you have to tip up the trowel will vary depending on how hard the surface is.

How to finish concrete smooth with a hand trowel

In Conclusion: Finishing concrete smooth by hand just takes some practice and an understanding of the timing of when to start and how long to let the concrete set in between passes.

It's a skill that requires just doing it over and over again. Watch and learn from the videos. I give you a lot of tips and details about how to finish concrete, then I show you how to do it.

Subscribe to my YouTube channel to learn a lot more concrete finishing tips and techniques.


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