In February I got a call from my friend Oscar asking if I would go to Puerto Rico (PR) to help him pour a top for his cooking island. I was a little hesitant since I hadn’t done anything that big myself. I ended up going and here are some pictures from the trip.

Oscar and I have an uncanny shared interest in concrete surfaces.  Several years ago we realized we both had the same book, Conrete Countertops, by Fu-Tung Cheng. Not long after, we were experimenting with some concrete at the studio and made this.

I flew to San Juan where Oscar picked me up. It was about a 50 minute ride to Humacao.

One of many coves close to our destination. Most just down the road and around the corner. 

The countertop we were going to be doing was of course, organically shaped, not nice straight edges as shown in Cheng’s book.

O cutting the mica that will be the bottom of our mold.

One of the problems for us was going to be making the curved sides of the mold. We opted for cold molded plywood. We used 1/4 inch luan ply for the long radii and an 1/8 inch scrap plywood spacer this cool guy at Home Depot gave us for the tight radii. What a stroke of luck it was to find that thin ply. Bent with the grain the thin ply formed perfectly. We used contact cement for the glue as it would set quickly allowing for fast mold completion. For more rigid type cold molding, contact cement isn’t good since it will spring back and allow the ply to delaminate. 

First of four layers including the mica. We used blocks for support and to anchor the mold to the two 3/4 ply table top that O had made for this job. 

The long radii were made using the 1/4 inch plywood so we were able to space the blocks further apart. 

Molds almost ready for caulking. The countertop was over 8 feet long and at 520 pounds we opted for a two piece mold. Nested together, the two molds fit perfectly on O’s 4 x 8 work table.

O removing the masking tape after caulking. Cheng’s video was also very helpful in reminding us of the steps we needed to follow. 

After waiting for the caulk to set over night, we installed the rebar and inlays. 

It was decided that we would pour after lunch. It would give us time to relax. For me, the pouring was going to be the biggest question mark. For my terrazzo tops I use white portland and play sand. The play sand has a very uniform grain size. For this job we would be using PR Quickrete and Cheng add mixture. We were a little short on the add mixture and  the PR concrete is a different consistency than the stuff in the US. We learned after the fact the importance of pouring a test mold if in doubt. But all was not lost.

Mixing the concrete and Cheng add mixtures. O had opted for a blue color. Note O’s horrendous working environment. 

O and I were very worried about the water content. We had already gone over the specified amount of water called for on the bag and the stuff was still too dry. Cheng called for less water then the bag specified because the add mixture contained a water reducer. We went ahead and poured.  We figured voids could be dealt with, weak concrete though, might be a problem. The mixture was way to dry and did not flow.

Using a hand vibrator to vibrate the mix.  

Relatively dry concrete. 

On the morning of my departure to return to Miami, we popped the mold off the counter top. O still has a bunch of work as the dry concrete had a few voids that he’ll need to fill with slurry. 

Oscar grinding the top with his wet grinder and 40 grit diamond disc. 

Close up showing  porosity in the top. You can also see the large sea shell sand that is used in the PR Quickrete concrete. The sand is almost the size of terrazzo aggregate. It made for a very unusual consistency. 

Hopefully Oscar will send pictures of the top installed with the contrasting slurry he’s going to use to fill the voids.

Thanks for stopping by. I’m hoping your April is going by in a great way too. 

Cheers,

Paul

More pics from O:

Bar top mold. I noticed here that the little blocks seem pretty normal…… 

Here though, O has MARKED them all….. hmmmmmmm. Mold looks nice.  

Both Bar top and Island top done and in place. O did all the cabinets himself. Great job for his first project. 

Close up showing the aggressive aggregate that the PR concrete contains. O used standard concrete for the Bar top instead of the high strength mix that we used on the Island top. Still needed a lot more water but the finish was really smooth and void free. Having the vibrator clamped to the table was a big difference according to O. I like this shot cause you can just make out the PM Custom stainless bar legs.

Mold for the main counter showing sink insert and other inserts for cutting board and dish drain.

The finished Kitchen: 

More pics to follow.

Cheers,

Paul