Concrete can be finished in many ways. Most of the concrete we see in the built environment is dull and grey, but there's so much more that can be done to finish concrete and make it look stunning.
There's two ways to think about finishes for concrete: finishes that are applied while the concrete is curing, and finishes applied after curing. Textured finishes like scoring or stamping are applied while the concrete is wet, like what you see on sidewalks - while interesting, texture-based finishes are a subject for another class. In this lesson we'll only be covering finishes applied to smooth concrete after it has cured completely.
Concrete is really good at accepting color. In Lesson 2, we talked about color pigment that can be added during mixing, but it can also be easily applied after curing.
Stains can be applied to any cured concrete, and has a translucent look so you get the color desired but also keep some of the dull grey look of the concrete. Stains can be bought as a premixed color, or you can buy the base at your paint store and have them tint it to match a color scheme.
Paint is a great way to completely cover concrete with an opaque color. Concrete is easy to paint and will accept any acrylic latex or oil paint. Special concrete paint is formulated to withstand abrasions that concrete is likely to incur, however any paint can be applied to a clean, debris-free concrete surface.
There's a reason all my concrete projects aren't covered in paint or stain, the natural look of concrete is amazing.
Unlike finishing wood to seal and protect from rotting, you're only really sealing concrete to protect from staining. Depending on the look you are going for, some inadvertent staining or aging of concrete can have a really nice patina and look great. While I'll cover some great finishes for concrete here, it's by no means required.
Clear polyurethane spray is easily applied and has a slight "wet look" sheen, but will have a slight shine to the finish. Though a fine finish for concrete, does look a little out of place on concrete.
Mineral Oil is inexpensive and can make a great finish. Apply mineral oil liberally with a rag; concrete is porous and will wick up the mineral oil quickly, so multiple coats will need to be applied. The dark color it turns the concrete is attractive, however this finish evaporates over time and will need reapplication regularly.
Concrete Sealer is specially made to give that classic "wet look" that makes concrete pop and will seal the concrete with a protective finish that will prevent any accidental staining. When applying sealer it may look milky white, but it will dry clear. Apply the concrete sealer with a foam brush or rag, then wipe up any excess from the concrete surface.
There's a few options when it comes to clear finishes to concrete. Here's a look at a few I tried and how they appear next to each other. In my opinion, nothing beats the "wet look" sealer, though.
While not required, finishes on concrete can elevate your work and really give it dimension - this is especially true with "wet" look" sealer.
Knowing what concrete finishes to apply to your work will allow your project to really shine.
If you're looking for a project to test your concrete prowess you can see all the skills learned in this class applied to a Tabletop Fireplace made from concrete
Are you having trouble with your concrete not curing right? The next lesson will cover some common troubleshooting tips for you to get the most of your castings.
Share a photo of your finished project with the class!
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