Antoni Gaudí i Cornet was born in 1852 and lived until 1926. He was a Spanish Catalan architect with a highly individualized style work. Nowadays Gaudi`s works are famous touristic attraction in Barcelona.

I tried to make a pot which looks like one of the most recognizable part of Gaudi's style, the chimneys.

Step 1: Tools and Materials

Materials

cement

masonry/concrete sand (beach sand is inappropriate because is salty)

fiberglass concrete fibers

ready for use cement mix (optional)

cardboard

3D Printer (optional, it depends on the shape of pot)

acrylic paint - red, blue, yellow and any other color

acrylic lacquer spray - white

clear lacquer spray - transparent (I prefer mat)

bolts M3x10mm

Tools

bucket

masonry trowel (or any similar tool)

wood stick

scissors / knife

ruler

painting brush N1, N2, N3

Step 2: Mold Preparation

I used a 3D printed mold, but for simple design you can use a cardboard or plywood mold. By my first pot it was impossible to extract the inside mold-part, that`s why I made the next one from cardboard. You can put a layer waterproof glue or lacquer on the cardboard, if is necessary.

Download mold files here.

If it`s necessary, use a wet dry sandpaper to smooth all surfaces (wet the sandpaper well).

pot_01.pdf
Download

Step 3: Casting

Recipe

Prepare a concrete mixture

1 part cement

3 parts sand

Water

Waterglass a.k.a. Sodium silicate (optional, made the concrete more strong and water-resistant)

a pinch of fibers (I bought a bag 0.6kg which is for 1 cubic meter concrete. One pot is around 430 cm3 which is 0.000430 m3, that means we need around 0.3 gr of fibers for this concrete)

Quantities
Assemble all parts and fill the mold with dry sand. After that empty it in separate container. Measure the volume of sand and add 1/3 volume of cement. (The cement is powder and will fill the gaps between grains of sand. The resulting volume will be a little bite more than the mold volume, but this is better than mixture isn`t be enough to fill it.)

Mixing

Mix it all to become a homogeneous mixture, then put a half part water and mix it again. Put more water (or waterglass) slowly to prepare a soft mixture. Be careful, less water give you stronger concrete after hardening but it is difficult for cast because is too dense. When I cast my first pot there were small bubbles after removing the mold. After that I made a little more flexible mixture. It takes app. 30 min. from the first drop of water to the time the concrete starts hardening, depending on the cement and water ratio. Have this in mind when organize how many pots you plan to make at the same time.

Fill the mold by small portion concrete and vibrate with gentle knocking. It is very important to remove all air bubbles out. This makes a stronger and better water resistant concrete. Repeat that step to fill the mold.

After you cast, put the mold in the shadow. If the weather is too hot cower the mold with wet rag. It depends on the mixture and cement ratio, but 48 hours after casting you can remove the mold carefully.

Step 4: Colors Adding

I use white spray for first two layers to make an easy paintable base. After that put the first colors: red, blue and yellow. If you have another rainbow colors use them too. If you don’t have any other colors you have to mix the first 3 basic colours to prepare green, orange and purple.

1 part red + 1 part blue = purple

1 part blue + 2 parts yellow = green

10 parts yellow + 1 part red = orange

Be careful with the yellow because it is less strong then the red and the blue. When you mix different colors start form lighter ones to the darker ones, adding them little by little. Apply few layers to make a strong homogeneous color. It depends on the color and paint, for example I made more than 5 yellow layers.

Step 5: Finishing

When you are ready with painting, it is good to finish the surface with one or two layers transparent lacquer spray, or to impregnate with water resist liquid. This will protect the pot from the water in future.