How to grind and seal a concrete kitchen floor?

[Hillmatt33]

Hi All

Has anyone ever done a grind and seal to internal concrete floors before?

Job overview, I want to grind and seal our concrete kitchen floor which was previously a games room which previously had carpet and underlay on top which we have ripped up, I am planning to hire from bunnings "Coates concrete grinder" and grind back the surface with a 40 grit diamond pad as we want a spotted look so will need to grind down a fair bit, then we will seal the floor with a topical penetrating sealer as we want long lasting durability.

Questions:

1. Like sanding wood do you need to use progressively higher grits to get a smooth finish with concrete? I.e., 40 Grit then, 100 Grit then, 240 Grit.
2. What is the best penetrating sealer to use? (We want a satin finish)

[EricL]

Hello @Hillmatt33 

Welcome to the Bunnings Workshop community. It's wonderful to have you join us, and thank you for sharing your question about grinding and sealing your concrete kitchen floor.

The Coates Floor Grinder comes with a default grinding disc attached. Unlike timber flooring, polishing concrete floors require the use of special grinding steel discs which are attached to the floor grinder. The default disc attached to the Coates grinder is used for smoothing rough finishes, levelling uneven concrete surfaces and removing tile grout and tile glue residue.

In regards to the sealer, the closest product I can find that fits your needs is the Crommelin 4L DiamondCoat Exposed Aggregate And Polished Concrete Clear Sealer. It's easy to apply can be thinned down and comes in a satin finish.

I also suggest having a look at this discussion - Polished concrete in a family room? by @ShawnWilkey. 

Allow me to make further inquiries in regards to the type of finish the Coates grinder will provide. Once, I have more information, I'll get back to you.

If you have any other questions we can help with, please let us know.

Eric

[EricL]

Hello @Hillmatt33 

I've been speaking to the Coates information team and the disk attached to the grinder will only provide a basic levelling finish. Swirls will be visible on the surface, and it will not give you a finished paintable surface. I recommend having a think about how you would like to proceed. First, you can hire specialised floor grinding equipment and do it yourself. Second, I suggest getting a quote for a concrete floor polishing service only. This will leave you with the option of sealing the concrete yourself. 

As a possible alternative, there is always the option of tiling your floor area with something very similar such as the Johnson Tiles 600 x 600mm Anthracite Peak Matt Porcelain Floor Tile. You can use a small gap of 1.5mm and grout it in the same colour to achieve a flawless finish. 

If you need further assistance, please let me know.

Eric

[Hillmatt33]

Hi Eric 

Went with your first suggestion!

"The Coates Floor Grinder comes with a default grinding disc attached. Unlike timber flooring, polishing concrete floors require the use of special grinding steel discs which are attached to the floor grinder. The default disc attached to the Coates grinder is used for smoothing rough finishes, levelling uneven concrete surfaces and removing tile grout and tile glue residue.

In regards to the sealer, the closest product I can find that fits your needs is the Crommelin 4L DiamondCoat Exposed Aggregate And Polished Concrete Clear Sealer. It's easy to apply can be thinned down and comes in a satin finish."

The coats team was super helpful and gave me a crash coarse in how to get the best result from the grinding.

The Sealing was the easy part, used the cromellin Diamond coat, the only thing I messed up was putting it on too thick and there was hard air bubles on the floor.

Pretty happy with the result.

Thanks

[MitchellMc]

That's great to hear @Hillmatt33! Any chance we could see some pictures of the finished job? Let me know if you need a hand uploading images.

Well done.

Mitchell

[Hillmatt33]

Hi Mitch 

No problems, here is the before and after!

Also another tricky part was filling in the gaps around the edges with concrete and getting the colour right, holes were caused by nails from when we pulled up the carep.

Thanks