Today we fortify the form for your mosaic flower. Begin by cutting the plaster tape into small (2-3 inch) triangles and rectangles. Prepare a pan/bowl of warm water.
Have all your materials and supplies at hand and begin by dipping one piece of plaster tape into the water. Take care to not drip water onto the dry plaster cut pieces or it will ruin them. Wet the piece thoroughly yet do not get it too wet. With practice you will discover the right amount. Now apply the wet plaster tape to the flower armature. Overlap the tape as you go and make certain to press firmly into the wire mesh for good adhesion.
Continue to wrap the armature in plaster tape, inside and out until your entire form is covered. Add a second layer. Be neat.
Let the plaster cure until it is all the way dry to the touch. Check for flexibility. If the form is too flexible, the mosaic will crack. Reinforce seams and petals, if neeeded.
Now, decide whether your flower is for the indoors or out. Proceed accordingly:
Seal the plaster tape with a solution of Weldbond Glue and water (1:4). Let dry. Mosaic using Weldbond Glue as your adhesive.
Mix thinset according to directions on bag and to a consistency like peanut butter. Apply thinset neatly to the plastered form using a pallet knife. Smooth ridges and bumps with a gloved finger dipped in water. Do not add too much water, just enough to smooth the surface. Let cure overnight.
Optional Step: Use a waterproofing membrane.
Waterproofing membrane is sold at your local hardware store in the tile and flooring department. It is a paintable medium that provides a waterproof barrier and flexible membrane to your substrate. Paint it on according to the directions on the bucket. Two coats are required for most products. The one I use is pink when wet and dries to red.
For outdoor flowers use thinset as your adhesive. Thinset can be applied directly to the waterproofing membrane.
Let the mosaicking begin! Here is a flower in progress by Leta Durrett.
Pink mosaic flower (WIP) by Leta Durrett.
Why plaster the wire mesh? We plaster the wireform mesh because it is made of aluminum and I have heard that aluminum and cement do not work well together. The plaster cloth creates a barrier between the two substances and also provides some strength to the structure.
Why use a waterproofing membrane? The waterproofing membrane adds an additional protective and flexible layer to your flower armature. I am not sure it is necessary.
The next post will cover mosaic design, grouting and the finishing of the works. I am looking forward to seeing your flowers and will post pictures from some of my students as well.