What do you need for a tabletop of 4.10m x 0.7m:
- handheld concrete mixer
- sand (masonry sand 25kg)
- cement (portland grey)
- furniture panels (melamine board) for the mold
- piece of PVC tube for the recess of the faucet
- window squeegee
- water sprayer
- cement bucket
Step 1 - going to the hardware store
The first step towards a homemade concrete countertop is to make the mold. The mold is made from melamine chipboard, also called furniture panels. The type of wood is cheap and available in almost every hardware store. Measure the size of the desired countertop and your sink and stove for the recesses if applicable. You can then have the panel cut to the right size at the hardware store. TIP: Add the thickness of the wood to the length and width of the sides and ends; you need that space when you screw them to the base plate. Then use our concrete calculator to calculate how many DIY-sets you need based on the dimensions.
TIP: For the recess of the stove and the sink we also use furniture panels and for the faucet a piece of PVC tube.
A countertop thickness of 3cm was maintained. It is the minimum thickness that we recommend when making a 4m countertop. However, it is then necessary to add extra reinforcement to the concrete. So, also add a fiberglass mat/AR glass scrimm in addition to the glass fibers from the DIY set. If you use your countertop for a kitchen, then the kitchen cabinets will also offer support. TIP: If you want an ultra-thin countertop, carefully consider its size and where it will be placed. In the end, many factors will influence the thickness possible for your countertop. And, sometimes, you just have to try it out.
Besides buying the furniture panels, also buy a bag of masonry sand and grey portland cement at your hardware store. Together with the DIY concrete set, you now have everything you need to get started!
- We made a concrete sink for this customer. A separate MDF mold has to be made beforehand for this kind of sink, which is quite tricky. We will tell you how this mold was made in a next, separate blog.-
TIP: The kitchen cabinets in this project are from IKEA (METOD kitchen system). They are sturdy, affordable, and together with the IKEA wooden front panels, they give the black, concrete countertop an industrial, chic look.
Step 2 - screwing and sealing
Now the mold can be screwed together. - Because of the cramped space, we placed the mold on the kitchen cabinets instead of on the floor. -
Then glue in the recesses and seal all the edges.
We used 'Dow corning 796 grey' to seal the edges. This sealant is acid- and solve'nt-free and therefore does not damage the concrete. Thus perfect! After applying the sealant to the edges, smooth the edges with your finger or a sealant caulking tool. Leave the sealant to cure for 24 hours.
Step 3 - waxing, mixing the concrete, and pouring
After the sealant has cured, release wax can be applied to the mold. We use our own demoulding wax, which also does not affect the concrete and ensures a clean result. Put a little wax on a microfibre cloth and apply a thin layer to the inside of the mold. TIP: If you do not smear out the wax properly, it may be visible in the concrete.
After you've waxed the mold, you can mix the concrete!
- We use the 'wet-cast' method for this project, in which the concrete is poured upside down into the mold. In step 4, the cured concrete countertop is removed from the frame and placed upside down on the kitchen cabinets.-
Order of mixing: combine the sand, cement, HDH SP, and HDH CURE and mix. Add 20 % water (calculated over the weight of the cement). If necessary, add small amounts of water until a custard-like substance forms. Then add the AR glass fibers and mix them briefly until they are well dispersed, and you're done.
TIP: Pour a part of the concrete mix in 1 place in the mold. You can already see that it's spreading out nicely. Use your hands to help spread it if necessary.
If you use a fiberglass mat, lay it on the concrete when the mold is half full so that the mat rests on the first layer. Then tap the edges several times with the hammer so the air bubbles can surface. Then pour the remaining concrete into the mold.
Once you are done pouring, tap the side of the mold with a hammer. This will help to release any remaining air bubbles. Then cover your project with garbage bags and let it rest for two nights.
Step 4 - removing it from the mold and finishing
The countertop can be removed from the mold after 36 to 48 hours. Because the countertop was cast upside down and weighed about 150 kilos, we flipped it with four men.
TIP: AIR BUBBLES
You may see some air bubbles after flipping the countertop. They also appeared at the bottom of the sink when we made this countertop. In this case, you mix concrete using: 1 part cement, 1 part ultra fine stone powder, (optional) pigment, and water. Mix it into a liquid.
Spread this mix all over the countertop, filling the holes, and then smooth it with a filler knife so that the entire countertop is moistened. This way you don't get any color differences afterward. Then completely cover the countertop again and let it rest for 24 hours. Then on to the finishing.
Afterward, the countertop is moistened using a plant sprayer (filled with water) and lightly sanded with k240 sandpaper. The water is then removed using a squeegee, and the countertop is sprayed and sanded lightly two more times. After the last sanding and after the water has dried, the concrete countertop can be coated.
We used a coating agent developed by us for this countertop, HDH Impreg. It's a scratch-resistant, natural coating that hardly has any odor and has a color-intensifying effect. And, it is a food-safe. You have to repeat the coating several times, and after that, the countertop is ready to use!
The paneling will be placed on the kitchen cabinets shortly. As soon as we have a picture of the end result we will place it in this article.
Would you like to make your own kitchen countertop, but you still have lots of questions? Then e-mail us. We will answer your questions as soon as possible and will be happy to provide you with information and advice.
Daan en Renske