Main Kitchen Countertop – West

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August 26, 2010
This countertop segment will extend to the right of the southwest countertop that holds the kitchen sink. It is a simple shape except for the diagonal end that butts up to the refrigerator space.

Here’s the first layer of concrete going in. This is the layer that will show, so it uses about 2/3 clear glass and 1/3 green glass.

We After placing the first layer we sprinkled confetti glass around the edges, and then used the vibrator to consolidate the concrete.

This countertop shouldn’t experience much stress so we just used a simple sheet of reinforcing mesh. Once it was in place we mounded up concrete from the first batch around the edges, sprinkling in more confetti glass around the edge.

The second layer uses all brown beer bottle glass, and we spread it across the top of the mold where it won’t show in the finished countertop.

August 31, 2010
It came out of the mold cleanly and the surface looks nice and solid.

Nash used the 50-grit diamond wheel to grind down into the glass aggregate.

September 18, 2010
After several coats of slurry and polishing up to the 1500 grit diamond wheel, the countertop was ready for installation. Liz applied a sealer and then we waxed it before moving it in to the kitchen along with the southwest segment that will hold the kitchen sink.

Here are a couple of close-ups showing the glass in this section.

Main Kitchen Countertop – Southwest

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August 18, 2010
This 6-sided segment will hold the main kitchen sink, with a 7.5-inch dropped apron in front. The first photo below shows the glued up template on top of the base cabinets. After making the template, we flipped it over and used it to make the mold the right shape. The second photo below shows the finished mold with confetti glass sprinkled into it, read to pour the concrete. The side closest to the camera will go along the wall, and on the far side you can see the outer wall of the “chimney” that will form the dropped apron in front of the sink.

August 19, 2010
We mixed the concrete using the same proportions of ingredients as the last (north) countertop, but it came out quite a bit more fluid. Maybe we incorrectly measured one of the ingredients or maybe we just mixed it a little longer, but it was quite soupy. We quickly went back and double-checked the ingredient list, and confirmed that we had the same recipe so we went ahead and poured it even though it seemed very wet.

After placing about 1/2 the concrete, Jay ran the vibrator over it to remove air bubbles. Then he placed a welded-up rebar frame in the mold. Considering how wet the concrete is, it’s good that we have the extra strength of the welded rebar frame all around the sink opening to help prevent cracking. It should be plenty strong once it is installed, because it is supported by a cabinet on each side of the sink. Our main worry is that it might crack while we are removing it from the mold, when the concrete won’t have reached full strength yet.

Although the concrete was quite wet on top, we did our best to screed it off level. The second photo shows the chimney being filled. This will make the apron in front of the sink, so we placed additional colored glass into it as we added layers of concrete and vibrated it.

The top surface was the consistency of pea soup, way too watery to make a strong concrete. In order to save the piece, we used scrap towels to remove the excess liquid from the surface. The concrete under the soup was firm but about 1/8″ below the top of the mold, so we mixed up some mortar paste from Portland cement and sand, and troweled it up to the level of the mold. The high water content overall is still a concern but it looks like the vibration consolidated the lower layers and made the excess water rise to the top, so by removing it with towels and filling with mortar we hope we have made a strong piece. Next time we’ll cut back on the water a bit!

August 24, 2010
We let it cure for 5 days before removing it from the mold. This is 2 days longer than the minimum curing time, which will make it stronger and less likely to crack while we turn it over but also harder to polish. As soon as we removed the front of the mold we were disappointed in the quality of the concrete, because it shows quite a few voids in the front apron. It should be plenty strong enough, but this will mean more work to fill all these voids.

We flipped it over and removed the bottom of the mold, and were relieved to see that the top surface looks pretty good, with very few voids compared to the front apron. It doesn’t look good at this point but we won’t know how it is for sure until we grind off the outer layer.

Nash spent a couple of hours grinding down to expose the glass aggregate, and overall it’s looking pretty good. In the second photo below you can see how it will look while standing just to the right of the sink.

The front apron does have quite a few voids, but it’s not as bad as we had feared when we first removed it from the mold. It will be a bit of work to fill the voids but it’s definitely fixable. Next Nash will apply a slurry of Portland cement and sand to fill in all the holes, and then we’ll let it cure for a few days before polishing it again.

September 20, 2010
It took several coats of slurry to fill in all the voids and a lot of polishing, but at last it’s ready for installation and Ryan applied a coat of wax.

Although the south segment was not quite finished yet, we moved it into the kitchen for a temporary test fit so that we could shim up the sink segment to the proper level. Then we moved the south segment back to the polishing area, and used silicone caulk to fix the shims under the sink segment and the one to the right. Then we installed the kitchen sink.

Here are a couple of close-ups showing the glass detail around the front corners of the sink. Despite the number of voids that were in the apron in front of the sink, now that they’re filled and polished you can’t even tell where they were.

Main Kitchen Countertop – North

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August 8, 2010
The first countertop will go along the north wall of the kitchen, and it has a cutout in the middle for a cooktop. It’s an unusual shape so we made a template from strips of plywood glued together with hot-melt glue. After flipping the template upside-down (very important!), we used it to locate the walls of the mold. This is the biggest countertop we have made, and it will be over 8 feet long and will weigh about 250 pounds.

August 11, 2010
The cutout for the cooktop leaves only narrow strips of countertop in front and behind the opening. In order to remove it from the mold and polish it we’ll have to put it under some stress before the concrete is fully cured, and it would surely crack in these areas without some reinforcement. We cut lengths of 3/8″ rebar to fit along the front and back edges of the countertop, and tied them together with reinforcing mesh across the middle. This should provide enough strength to keep it from cracking, as long as we handle it gently and avoid twisting it as we remove it from the mold.

August 12, 2010
We mixed up enough confetti glass for the entire kitchen, so that all of the countertops will have a similar mix of colors. We then weighed out the same amount of confetti glass per square foot as we used in the test piece and spread it more-or-less evenly throughout the mold. It includes a variety of sizes from larger pieces all the way down to dust.

At last it was time to place the concrete. We used a bit more water in the mix this time so that it would flow more smoothly, and it should release trapped air bubbles more readily than the stiffer mix we used in the middle bath countertop.

There is no particular pattern in the arrangement of the confetti glass, but we tried to disturb it as little as possible while pouring.

Once it was poured, it was jiggled by hand to spread it out and to help embed the confetti glass on the bottom. This probably moved the confetti around a bit but it’s no big deal since we’re not trying to maintain any particular pattern.

To consolidate the concrete and release trapped air bubbles, Jay ran the concrete vibrator over the surface. The vibration momentarily makes the concrete very fluid and it seems to be boiling as air bubbles rise to the surface, and it also causes more of the glass to sink to the bottom of the mold where it will show on the top of the countertop.

This mix fills the mold about halfway, so that the rebar will end up just a little below the center when the countertop is flipped over.The rebar is placed on top of the first layer, and pressed lightly into the surface. It’s important to have everything ready and work quickly, so that the remaining mix won’t stiffen up before the chimney is filled.

Once the rebar was in place we attached the chimney and filled it. Because this will form an apron in front of the cooktop, we want it to show the same mix of confetti as the top surface. As Jay placed the concrete into the chimney, Liz sprinkled colored confetti glass along the front where it will show. Sorry, there’s no photo of that since we ran out of hands.

We mounded up the remaining concrete from the first batch along the front edge of the mold, where it will show. Again we sprinkled some confetti glass along this edge so it will blend in with the top. That completes the first layer of concrete.

The second layer of concrete uses the same mixture as the first layer, except that it uses all brown bottle glass that won’t show in the finished piece. We made a bit less in this batch since it doesn’t have as much volume to fill as the first batch.

Once the concrete was all placed, Jay used a board to screed it level.

The finished surface is fairly smooth, and we made sure that the mold was level in all areas and not bowed or twisted so that the countertop will be flat. There was just a little concrete left over, which we placed into the square mold sitting on top in the second photo below. We’ll use that as a stepping stone in the garden. Now we need to wait about 4 days so that the concrete will be strong enough to be taken out of the mold without cracking, but still soft enough to grind down to expose the glass.

August 16, 2010
We removed the sides of the mold and carefully flipped the countertop over onto foam strips, then peeled off the bottom of the mold to reveal the concrete. The results look very good with few bubbles, indicating that the increased water and vibration consolidated the concrete well. A few taps with a rubber mallet removed the cutout block in the center where the cooktop will go.

Our nephew Nash started polishing it with the 50-grit diamond disc, and slowly the colors were revealed.

The two photos below show the areas to the right and left of the cooktop. These are taken from the side that will go against the wall, so the front of the countertop is at the top of the photos.

Here are two more shots showing a close-up with a hand for scale, and an overall view. Although the surface has few bubbles, there are still some voids that must be filled so we’ll need to apply a slurry coat before polishing it any further.

August 25, 2010
After applying a slurry to fill in the voids and letting it cure for a few days, Nash polished it down again. We repeated this process several times in order to fill in all the little voids, because the slurry doesn’t always fill every void and each time it was polished a few new voids were uncovered.

September 3, 2010
Before polishing the top to the final finish, we flipped the countertop upside-down and smoothed out the rough areas where it will sit on the base cabinets.Then Nash polished the top all the way up to the to 1500 grit diamond wheel.

Once the top was super-smooth, Liz applied the sealer. It was a windy day and afterward, we discovered that the sealer had dried so fast that it left very visible streaks on the surface. So we had to scrub off the top layer of sealer and scrape it with razor blades to get down to the smooth surface again. This still left plenty of sealer below the surface, which is where it is needed. The sealer doesn’t make the countertop look shiny; it just makes it relatively impervious to liquids.

September 8, 2010
At last we wheeled the countertop into the main kitchen. Nash applied a coat of countertop wax and buffed it to a nice shine.

This countertop weighs about 250 pounds so installing it had to be done carefully to avoid injuring the people or the countertop. Nash and Jay stood it up on edge and then lifted it from the rolling work table onto the base cabinets.

From there it was relatively simple to tilt it down and slide it into place.

We hadn’t actually tried putting the cooktop into the opening in the countertop until now, but fortunately it fit perfectly and it looks great. This completes the first of five countertop segments in the main kitchen.