Several questions have been raised in the Comments section of a previous post showing that mosaics interest readers. Therefore, I propose to expound on mosaic-making technique as I understand it. Keep in mind that I am self-taught and this may be all wrong.
First of all, the best bases for me are terra cotta and clay pots, which can last 25 or 30 years in an outdoor environment. Adding the tiles and cement should extend their durability by years. I don’t bother with wood, as it has low durability in my area. However, recycling is important and I have been gluing mosaic pieces onto metal paint cans and buckets and then grouting with cement (yeah, just plain Portland cement, no sand added), which seems to work in the short run. I would expect those containers to last a minimum of five years, but eventually they will rust from the inside. Same can be said for the oil tin cans I use. Since I cement the bottoms, they could last longer because the cement and tiles form the container. Time will tell—I’m rather new at this. I’ve been toying with the idea of using plastic detergent containers in order to recycle them. Cheap plastic Christmas tree balls make cool “orbs” that can be hung in the garden.
Warning: wear a mask when working with cement, and watch out for your back—the larger pots can be heavy. One must choose carefully where they will be placed because once planted, they’re difficult to move, needless to say.
On the creative side, I never sketch mosaic designs and I find that I have nothing to say about the design process in my journal. Remembering that it’s “just” a flower pot is liberating. A couple of simple rules: make many and make every design different. I reflect on possible designs and work it out on the pot with a few penciled lines. Generally, one design leads to the next.
I cut one color of tiles (usually white) with nippers to get rectangular or triangular pieces of the same size (more or less) to work into a design. Then I add the fill-in tiles, which are smashed with a hammer. One should use "thinslip" to adhere tiles to the surface for outdoor projects and there's a special mosaic grout. I haven't found them locally so I use a very strong glue (and keep the windows open or glue outside) and use cement for the grouting. Seems to work. I've also seen resin used, which makes the mosaic lighter, however, I can't vouch for its durability. I darken the grouting cement with a black paint product used for mixing wall paint--once again, seems to work. I've also used white cement for grouting if the tiles are dark. Other colors can be added.
Having saved tiny pieces for awhile, I’ve accumulated enough to use in parts of designs. Here's a floral motif:
There still remains room for a few more pots going up the stairs to the roof.