In terms of pushing the limits of cementitious materials, Willy Guhl's work for the Swiss fibre cement manufacturer, Eternit, is some of the earliest and best. The Loop Chair he designed in 1954 was pushing the boundaries of the material back then, and even today we rarely see concrete or cement mixes being pushed so far.
Guhl's Handkerchief Planters (c.1960s) in particular were the inspiration for this project. In the process photos shown here, you can see they are draping the material over a frame. What we're going to do is roll out the material on a piece of fabric and drape it into a large bowl.
Ordinary concrete mixes won't work for this project. You'll need a mix with properties similar to ShapeCrete, which can be mixed to a clay-like consistency and then formed into thin shapes. It's stronger than a bagged concrete mix, can be cast thinner, and can be removed from the form in only 24 hours.
Materials and Supplies:
- Vinyl Type Fabric
- Shallow Bowl
- 10 lbs. ShapeCrete Mix
Step 1: Watch the Video
You can watch the How-to video here, or continue reading for step-by-step instructions.
Step 2: Cut the Fabric
The fabric is used to support the mix when it's placed in the bowl. This helps keep it together and also gives the outside of the piece a textured finish.
Type of Fabric:
The most important thing is that the fabric won't absorb water. It should also be slightly stiff, like vinyl, so it will hold a shape. It can be smooth, or textured. The texture will be mirrored perfectly in the finished piece. It doesn't matter what color the fabric is, so sometimes you'll find ugly but cheap fabric that's on sale.
Draw out a large circle about 2' in diameter on the fabric. Leave some tabs around the perimeter. These will be used as handles.
The shape and size of the bowl will determine how the fabric will fold. A larger, shallow bowl will work just fine. A 5-gallon bucket will give you a more vertical piece. Experiment with this.
Step 3: Mix and Pack ShapeCrete
Just add water and mix ShapeCrete to a Clay-Like Consistency.
Pack on fabric:
Spread out the mix out to the edges of the fabric, maintaining a thickness of about 3/8".
If the mix was very wet, it will just slide down the fabric. In this case, wait a few minutes and lift up the edge of the fabric. If it slides down, keep waiting. If it holds the shape, it's ready to go. On the other hand, if you wait too long it can cause some cracks to form on the tighter curves. After working with the material, you'll get a feel for when it's too wet or too dry or just right.
Place in bowl:
With the help of a friend, lift up the fabric and drape it into the bowl. You can manipulate the shape and smooth out any cracks that have formed. If you want the piece to be a planter, you can poke a hole in the bottom with your finger.
Cover and cure:
Cover the piece with painter's plastic and leave it to cure overnight.
Step 4: Remove Fabric and Sand Edges
After the piece has cured for about 24 hours, it can be removed from the bowl.
Gently peel away the fabric. Smooth the edges with diamond hand pads, sandpaper, or a file.
Step 5: Finished Piece
For more project ideas be sure to follow us on Instructables, and check out our Project Guides on shapecretemix.com