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Saturday, May 19, 2012

DIY Cast Concrete Tiles


My garden took a hit last year from the extreme drought Texas suffered. I'm slowly building back my beds, but I'd like to look at something other than mulch while I wait for the glories of summer.

Jewelry takes people's minds off your wrinkles.
  ~Sonja Henie

Why not add some pretty tiles and stepping stones to fill in some of the bare spots?


I loved the artwork in Color Cement Handicraft, so I took screen captures of the chapter headings and simplified some of the drawings. I also added a word just to see if it would work. Notice that the drawings are not flipped in reverse.


I cut squares of insulation foam to fit each potential tile. I just eyeballed the tile shape. I'm trying to break myself of perfectionism.


I found that taping the image to the foam and simply drawing over the lines with pressure to make an indentation was adequate to transfer the image.


I then retraced all the lines in ballpoint pen to make them stand out. Don't press the paper so hard that it tears as you're tracing. If you hear a crackle, you're tracing hard enough.


Now for the magic. Get a mask, go outside, and heat up a wood burning tool or a soldering iron. Running a hot tool through insulation foam is like running a hot knife through butter, except with more fumes. This process is smelly. But look!


In the book Color Cement Handicraft, the authors make a plaster tile and incise it with a sharp object to transfer the designs. I just did it with foam instead.

The foam tile is the master design. I had to make a mold from the master before I could pour the cement. I cut 2–in. bars from the foam and duct taped them around the tile. I also used wire brad nails pushed into the foam on the corners to add more pressure to the sides.


Spray vegetable oil makes a great mold release. I sprayed the boxes and wiped out the excess oil. I am not a master plasterer, so I can't tell you how to mix up plaster. I basically mixed it so it was pourable without being watery. I poured each plaster tile to about ¾–in. thick.


In my dry heat, I was able to unmold each plaster tile after about 15 minutes.




You have to let the plaster molds dry thoroughly (for at least 48 hours) before you can move to the concrete casting step. When my molds are dry, I will spray them with clear enamel or shellac to protect the lines from rubbing off during casting.

I started another tile earlier. Here are the concrete casting steps:

1. Place the foam spacer bars around the plaster mold using duct tape to secure the spacers to the bottom and wire brads to secure the sides. Use the same process as you used to make the foam mold.

2. Spray the shellacked plaster box with spray mold release or vegetable oil and wipe away the excess.

3.  Mix the concrete, topping sand, OR sanded grout until it is thick but pourable. Protect your hands with kitchen gloves. Protect your lungs with a dust mask. I used sanded grout because it is a cement mixture that already contains color pigments, and I wasn't planning to step on the tiles. I have several bags of grout left over from previous tiling jobs. If you need weight–bearing tiles, use concrete ready mix. The added aggregate gives the cement strength.

4. Pour the cement mixture into the mold and let it set for 24 hours. After the initial setting period, you can unmold the cement tile. It will continue to gain strength as it cures. Keep it misted for at least three days after unmolding.

5. If the plaster mold and cement mixture do not want to release after 24 hours, use a thin piece of metal to pry the two apart (which is what I had to do). Once you get it started, it will release.

6. You also can cast the cement in the foam mold. Follow the same steps used to cast the plaster mold.

Stag tile in sanded grout. Cast from the plaster mold.

Stag cast in sanded grout. Cast from the foam mold.

Stag cast in sanded grout with craft sand and graphite powder added to the foam mold prior to casting.

As soon as the first three plaster molds are cured, I'll be pouring more tiles. I have more sanded grout and I bought a bag each of topping sand and concrete quick mix.


Sanded grout can stand up to the elements. I have proof here.

Thanks,
Aimee

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7 comments:

  1. I love this idea! I love working with plaster casting and this is an awesome way to come up with something unique! Great job!

    suzy

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    1. Thanks, Suzy. It's amazing how everything old is new again.

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  2. Making cast concrete is a very old tradition that can be traced back to the Ancient Romans. However, the process of making them still lies under the same principle. You have to control the concrete if you want a good outcome. What you did was even more challenging because you have to worry about the print as well. I’m thrilled with your work, Aimee!

    Salvatore Aguilar

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    Replies
    1. Thank you, Salvatore. I think I got really lucky on my first try. Almost every tile of my second attempt cracked. It really is about controlling the concrete.

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  3. This comment has been removed by a blog administrator.

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  4. Those are wonderful designs! You were lucky enough that your first try was a success! Practice makes perfect! Keep it up! Good luck!

    -Alphonse Daigle

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