Knowing the art of grinding and polishing concrete worktops is essential for a successful project’s completion.
Concrete is made up composed of cement, rock aggregate, water, sand and. It is, by itself, extremely brittle. But when sand and rocks are added to it, the matrix forms that helps strengthen the mix. The cement acts as a glue and helps to fill in the tiny gap that is left between the aggregate and sand. This makes concrete more robust than cement on its own. Because the rocks that is used in concrete mixes is mined locally, the types of rocks that you encounter will differ depending on the location you’re around the globe. The concrete pieces that are featured in this guide are made of an 8000 psi. concrete mix.
When casting concrete, the cement paste creates an uniform layer on the surface of the object, creating the piece as a single solid color that has minor variations. This is known as casting-finish. The cement layer is removed by a very gentle polishing. The polishing process will let the fine particles of sand that is in the mix, referred to as a light polish. More intensive polishing will expose the aggregate of the rock and create the appearance of a ground-finish. The least amount of material has to be removed in order to expose the aggregate to achieve an even ground (about one-quarter of an inch). ”).
This guide will demonstrate ways to shine concrete worktops. There are several possibilities of finishes you can get from a single slab of concrete. Polishing is usually done using the variable speed concrete polisher that has diamond discs for sanding. The polisher is typically run by water and is connected to a regular garden spout. The water helps to cool the pads and keeps dust to the low level.
Step 1. Safety Information
The process of polishing concrete worktops isn’t hazardous, however electricity and water don’t blend well. If your polisher isn’t equipped with an Electric ground Fault Circuit Interrupter you must be cautious to stay clear of electrocution. Even when using the GFCI It’s a good option to use rubber gloves in order to keep you safe.
Use a mask for particle protection if you’re engaged in any form of dry grinding. Concrete dust can be caustic.
- Cast Finish Light Polish Ground Finish
From just one slab made of cement, there is a variety of finishes can be made available based on the polish you use, and the depth at which you polish.
Uniform finish – Concrete exhibits an uniform color due to the fact that while it’s being formed in the form, it’s covered by the cement paste is a fine layer is formed on the inner surfaces of the formwork.
Light Polish When you begin to polish the surface the thin layer cement is removed while the fine, sand-like aggregate becomes visible.
Ground Finish – When you polish more deeply into the concrete you start to expose the larger aggregates in the mix of concrete.
Step 3 – Grinding vs Polishing
Grinding is thought of as the most rough method to flatten the concrete surface. Polishing involves bringing the concrete surface and polish it to a increasingly smooth, shiny, and polished appearance.
For pre-cast concrete projects, it’s typically necessary to employ grinders. Since the formwork will do the majority of the shaping, the only location you’d require the grinder is some part of the project that’s not visible (like the back of a worktop made of concrete).
Step 4 : Variable Speed Polisher
A variable speed wet-polisher is a tool with many uses. It can be used for any type of concrete work. It is also able to be applied to stones or other glasswork.
The Alpha polisher is powered by normal power from the wall (110V in the USA) and must be connected to the GFCI. The GFCI is a breaker that stops power supply to the device if electrocution risk is present.
The water feed line functions exactly like a regular garden pipe and is threaded onto an ordinary spout. The valve regulates the rate at which water flows through the middle of the arbor. In some polishers the water line feed can actually cool the bearings within the tool. Running it dry could cause a toasting of the bearings.
Step 5 – Different types of polishing Pads
Soft Pads – You’ll need an adhesive backing made of rubber that attaches to the polisher. Soft pads are more suitable for novices as they’re more accommodating. They also have the ability to polish surfaces with contours. Most commonly, they are used in conjunction using water-fed concrete polishers.
Rigid Pads require a quick release mechanism that connects on the polisher. The rigid pads polish faster than soft pads, however they may also scratch the surface when the pad isn’t firmly held flat. Most commonly, they are used in conjunction by an water-fed concrete polisher.
Dry and Wet Pads Need a quick release mechanism, however, unlike other pads they are suitable for use on the high-speed angle grinder.
Sixth Step – Get Wet Polishing Preparation
Make sure you know what you’re hoping to achieve prior to beginning the process of polishing. It is always possible to remove any extra material, but you won’t be able to remove it again and you must be careful.
Wear rubber gloves
You might want to consider the possibility of wearing rubber gloves as well as rubber boots.
Lift the piece onto the scrap of 2” of foam.
Polish outdoors in shade, If possible, or inside using an ironing table.
Create polishing tables (sloped table covered with plastic tarp with 6” tall walls, water drains into the plastic bin, a pump to recycle water, plumbing to water valves on hoses).
Step 7 – First Polish
For a smooth finish begin with the smallest the grit pad that you have typically 60 grit. Polish the surface evenly until a consistent amount of aggregate is visible, and then move on until the pad next.
To get a smooth polish Start with a middle-range pad, for example, 300. It is possible to remove any extra material, but it’s impossible to return to the previous level and you should be cautious not to begin with a low level if you don’t need a completely ground polish.
Tape off the areas you don’t wish to polish using a couple of sheets of masking tape.
Step 8: How do I Polish
Switch on the water source.
The polisher should be lifted above the surface, then switch the polisher on.
Place the polisher on the concrete, and let the weight of the device perform the job. Maintain the pad as flat as is possible.
The piece should be moved around in a uniform manner by making circular movements. Be sure to not start or stop at one spot over a prolonged period of time.
When you’ve got a huge area to polish, concentrate on small areas rather than trying to complete all at once.
The next pad will be completed until the surface is evenly polished.
Step 9: Fill the Holes Slurry
After polishing half way through, process (around 400-grit) Fill the visible holes with Slurry (cement paste, color along with water).
Start polishing again after the slurry is dry for a few hours.
Take a look at this How-To Slurry Guide for more details.
Stage 10: Final Polish
Get rid of the slurry by polishing the piece with the finer grit pads (400-grit and higher).
The last step is to make sure the piece is sealed. This will keep it looking good and protect the polished look.