Introduction: Cement Wall Art
Inspired by some images of wall art depicting fragmented animals in origami, I decided to give it a try and make it in a more durable material, as it will be an outdoor project.
I always liked horse drawings but I can´t draw one from scratch, so, I went to one of the big stock photo stores and bought a horse silhouette in the pose that pleased me the most. You can also find great animal illustrations in old magazines.
Then, all you need is to trace over them with straight lines and then divide the space as evenly as possible. Other animals work great too. It would be pretty easy to draw your own, for extra originality, especially if you chose an easier one, like a bird or a turtle. For the sake of this instructable, I´ll stick with the horse image I bought.
Desktop computer with Adobe Photoshop (or any painting app that lets you draw straight lines). This isn't necessary if you draw the designs on paper or acetate by hand. Its a question of saving paper, really.
Water (enough to make the cement mix pourable)
Powder color pigments, food colorants, fabric dyes, watercolors. You can use anything that adds color to the mix. Make some tests beforehand as some of the pigments are stronger than others. I use mainly powder pigments and they all behave differently. For example, a small amount of yellow ochre is enough to tint a bucket of cement. On the other hand, black is very weak and you have to put a lot. Be careful not to mix too much tough, as powder pigments make for a more fragile mix. Also, some are soluble in water while others are only in oils.
Step 1: Creating the Design in Photoshop
Open the horse silhouette image in Photoshop and go to image>adjustments>invert or press Ctrl+I on Windows.
I used Photoshop because it has layers and undo, so it's easier to go back and correct mistakes.
Create a new layer and draw straight black lines dividing the horse into areas that seem esthetical to you (image 2). For this image size (2500x2000 pixels) I adjusted the line tool thickness to 5 pixels. If you want to better see the effect of the slanted faces I'm after, you can also draw the edge lines (parallel to the borders, as in image 3) in a new layer. Try to divide the horse into pieces that fit in the available area. Big ones for the body, small ones for the legs and ears.
Also, try to make one or two kinds of pieces, as more shapes will be confusing. As a rule, I will only be using n sided prisms and pyramids. The big ones will have a plateau and the smaller ones will end in a vertex. I made several tries before I reached a solution that seemed alright. The trick is to keep everything homogenous and flowing. Without too small or too big pieces or round shapes instead of straight ones.
This step is a little boring but you'll end up with a drawing that contains all the information you need to accomplish the project. From this drawing, I made an acetate version to project on the wall and a paper version to serve as a template to cut the mold pieces in cardboard.
As an added step in Photoshop, I used a yellow marble texture underneath all layers to start seeing some color (image 4). And that's because initially, I was thinking of doing the horse in yellow only. To see this texture under the horse silhouette you have to either change the horse layer blending mode to multiply (which hides white parts of the image) or select the white with the magic wand and delete it. I personally prefer the first method, as the second might generate some nasty borders on the silhouette.
Step 2: From Computer to Wall
Trace the horse design from the screen by covering it with an acetate sheet secured with clamps. Use a good black permanent marker. The ink used in some of the pen models I tested produced very faint grey lines. Look for known brands. Also make sure the ink is really permanent, as some marker models were easily smeared by rubbing the hand over the drawing, which means they're not permanent or they take longer to dry. You can also, of course, use glass or acrylic but remember, the thicker the material, the more difficult it will be to trace accurately because of the distance to the paper/screen.
You can do it in a notebook like me or on a tablet, but avoid using monitors that get too hot, as the acetate will start to get bumpy and corrugated and change shape, making it impossible to trace the drawing accurately.
After watching some videos on Youtube, I eliminated the complicated and costly ones and made a projector with what I had around, an iPod and a shoebox. I cut a window on one side of the box and fixed the acetate with the drawing using a clamp. You can't see it in the picture, but all you have to do is put your smartphone inside the box with the camera facing the drawing. Now turn on the flash in video mode. The drawing appears very focused on the wall even if you didn't turn off the lights or close the box lid. At night it is even better of course, and you can see very clearly the design and trace over it. For tracing, I used a graphite stick, as it is easily cleaned from the wall after the sculpture is mounted.
In image 3 you can see the design transferred to the wall. I used a ruler, just to make sure the lines were really straight so I minimize problems when later I make the piece molds.
In image 4 I transferred the design to paper also, so I can have a template to check If all pieces are in the correct position and orientation. I also numbered the pieces so I don't get lost when mounting them on the wall. As I didn't have any big sheets of paper lying around, I just duct-taped some A4 sheets and then traced over the screen with the correct level of zoom on Photoshop. I did this to match the measurements the design will have on the wall. Use the thinnest paper you can get because it's much harder to see through the paper than through acetate.
Step 3: Making the Pieces
It's time to create the molds for the pieces. I decide from the beginning that I wasn't going to use Pepakura or a similar app. Although it is a great piece of software, I think I didn't need it to make the pieces, because they are relatively simple, and the fact of being separated pieces makes it even easier. If you want to be precise, though, and like your molds neat and tidy, even if they go to the garbage after, then use Pepakura or Dxf2Papercraft. The first is easier to use but is paid, the second is free but not very user-friendly. I suggest you try both if you can and see what suits you better.
I made the molds from heavy stock card instead of cardboard, which was corrugating too much and would leave deep marks on the pieces.
To make the molds, I cut the shapes using the numbered template I made before. Then marked the edge lines to know where to fold to create the slanted faces. Then I made a cut on each corner and folded the cardboard up creating the bevels. I could have cut the excess card sticking out on the sides (won't happen if you use Pepakura), but I left those bits to give the mold extra strength I just bend them over the edge. Then I stick some duct tape on the corners and the mold is done.
For the mortar, I mixed a batch of white cement, powder pigment and sand and only added water as needed to make each colored piece.
I made the mortar from 1 part white cement, 1 part fine sand and enough water to make it pourable. This mix ratio will give you a water-resistant and durable mortar. Remember, the more water you put into the mix, the weaker it will be.
Now, fill the molds with the mortar, taking care they are on a leveled surface, or you'll end up with some warped pieces. The pieces that end in a point or vertex are easily secured in a bucket of sand. Just stick the mold in the sand and level it.
In the picture, you can see a mold and 2 experiments. One with only white cement and sand and the other with white cement, yellow ochre pigment and some Portland cement (that's why the piece came out greenish). I was trying to use some Portland cement on the mix to make it cheaper, but it darkens the colors in a very dirty way.
I let the cement on the molds cure for a day, then I unmolded them carefully trying not to break the edges too much. If you can let the cement cure longer it is better, as the edges will be much harder and won't crumble so easily.
If some edges crumble, you can fix it easily with a file or rasp to restore the straight edge. If they crumble a lot, then you'll have to make another piece. For this reason, try not to damage too much the molds.
As a final step, I glued the pieces on the wall with glue cement. The kind used to glue tile to walls.
Hope you enjoyed this Instructable. Bye!
Participated in the
Stone Concrete and Cement Contest