Concrete floor

While waiting for the mosaic tile we planned to finish the concrete substrate floor made by the developer of the property. It turned out to be unsuitable for the finished floor. We were planning to stain it and seal it. Unfortunately the concrete was of such a poor quality and so brittle that we were forced to pour our own layer of self-leveling fast curing concrete.
It is a very simple process but extremely easy to screw up. The concrete cures within 20 minutes and that's the maximum amount of time you have to spread the mix around and smooth it. That means from the moment you pour the water into your concrete mix. We have divided the space into major areas and had a concrete mixer rented to speed up the process. We were not able to mix it all at once so we had to carefully plan every move and layout for every bucket poured, pre-measure batches of water and concrete and with a help of extra family members we did it in the course of 3 days.
Before we had to clean the floor of any loose material and prime it.
The floor was not perfect but good enough for our purposes. Some imperfections added to the character.

Priming:

Pouring concrete:
The last batch we had to mix by hand because it was already 11pm and we had a visit from the building security with a complaint from our neighbors about strange thumping sound from the rented concrete mixer.


Before staining (about 2 weeks later) we did several color tests with different intensity. We used an acid stain and seal product from French company Ezchem Europe that also provides a wax for final finishing. The results can be really beautiful but also quite unpredictable.

Final look:
The scoring of the surface was done before staining. We did it along the control joints that had been done according to our plans by the developer on the original floor. Having our own floor done on top of it allowed us to straighten the lines that were very crooked, sometimes missing the point by a foot!

Construction phase 1.

As I mentioned in the previous post - choose your contractors carefully. A red light already lit up while discussing the process of shaping bathroom floor and showers out of concrete. Unfortunately the light was too dim and we ran into some trouble.

We had the master bathroom floor raised to accommodate radiant floor heating that we used instead of a towel-hanger wall radiator. We used the same connection but routed the pipes in the floor. The floor was supposed to be a compacted, waterproof concrete with a depression in the shower.
The result were terrible!

We have also had a base created for mounting the bathtub faucet. After this we decided to demolish it and integrate it with the sink cabinet.
We had some of the drywall work done, plumbing for the toilets and shower mixers and were supposed to have the bathroom tiling done. The beautiful hand made mosaic did not arrive in time so we decided to let the contractors go and look for somebody else in the meantime.

Demolition

In all projects of this kind it starts with some amount of demolition. It was fun. At least for the first half hour. After 3 days you wish you had never started. We demolished all of the walls we needed to move in 2008 but had to wait a whole year until we gathered proper resources for the project.
These 2 fellows were hired by our first contractor. Choose you contractor very very carefully. Or just don't and do it your self. :)

Sink form finishing

Building forms was a relatively quick process in comparison to finishing. I wanted to achieve as smooth surface as possible that would not require polishing later on. I knew it was possible because we have done several concrete mix tests. We were pouring them into used ice-cream plastic containers trying different proportions as well as pigments. Most of the samples replicated the smooth surface of the containers nearly perfectly.
I've decided to paint the forms to achieve a seamless shiny surface. It would have worked great had we had it powder coated or used a similar process. Instead I have tried a dozen different paints, laquers, enamels and practically stripping it and trying again each time. It was the time when we were ready to give up the idea several times and just buy a sink of the shelf. Eventually the best results I have achieved were with a spray enamel paint made for repairing old bathtubs. It left a nice glossy surface and a fairly even coverage. There were problems along the way - unintended damages, repairs, running out of paint in the middle of the process, so it took several months on and off to have the forms finally finished. Considering the amount of time we have spent on them they are probably the most expensive sinks in the world made out of the cheapest available material. A very tough learning process.
Even though the form elements were cut precisely and glued fairly well they still needed a considerable amount of spackling, sanding and then rounding the edges.

Below is a picture showing problems with painting the surface I was running into.

Here is a picture the moment when finally the spray paint started yielding good results.
And this is a picture of the guest bathroom sink covered with anti-adhesive concrete form solution and inside edges rounded by filling with smooth gray silicone.

Sink form building

We have gone through several options while building the forms. One sink was supposed to be a curvilinear surface with only a small off-center depression for the sink bowl. The other sink for the master bathroom was meant to be more aggressive sharp-edged faceted form.

It turned out to be very difficult the get the right results while building the sinuous form using a sheet of thick acrylic and a heat gun. We had to use extra weight to push the surface down, but since we did not have access to vacuum forming tools, this method was very hard to control.
I have used 4 or 5 acrylic sheets and never achieved the desired smooth curvature I liked.
After this I tried sculpting the form out of rigid insulation foam. It could have been done with a CNC milling machine, but why bother if you can do it by hand? :)


Later I planned to cast gypsum into this form and then smooth and paint it to get the final negative top surface of the sink. But after wasting a bag of gypsum that cured in seconds in the mixing bucket I finally came to conclusion that it is time to simplify.
I have changed the design of the guest bathroom sink to a simple slab with a shallow rectangular depression. The only curvilinear element left was how the surface gradually sinks in from one side. I used the acrylic again but in a lot simpler manner.

The only complication was creating the negative forms to create cavities underneath so the it is not entirely solid. That reduced the weight by about 30%.


The faceted sink for the master bathroom was a little more straightforward. All of the geometry consists of planes. The difficulty was in connecting the planes at different angles.
We have built a 3D model of the sink surface and of the form that was to be made out of laminated particle board you can buy in any Home-Depot-style store.
Using a 3d model is not necessary but it was the best reference for measuring all of the angles. Each seam was mitered at a different angle that required adjusting for every single cut. I had to use both a compound miter saw pictured below as well as a table saw with a custom jig for nearly each cut.
Then what was left was assembling the top and bottom of the forms. Each had a distinct shape and angles to maintain a minimum thickness of the concrete slab and accommodating the drain that has its own minimum thickness to be installed properly.