How were these tiles made?

Question

I bought a box of various 2"x2" Mexican tiles to create a backsplash behind my oven:

What I want to do, is to make some of my own tiles to mix in - tiles that don't "stick out" as being obviously different, but which contain images personal to me. I want my tiles to use the same colors and the same design styles as the ones I bought.

So I'm working with a local ceramicist, she's got some red clay to match these tiles (here's a side view of one of the purchased tiles, showing the clay):

and she's working with the clay to figure out shrinkage amount and what thickness to start with.

But now we're looking at the designs on these tiles and trying to figure out what they did, so that we can match it. (BTW I've contacted the company and they don't want to give up trade secrets, I guess that's understandable)

Some of these tiles look like they could have been hand-painted:

and possibly even

but others are just way too intricate and precise to be hand painted:

Any idea what process they used to put the images onto the tiles?

Answer 1

They probably covered the tile in white glaze and then used a paint brush or sponge stamps to apply the blue glaze on top of the dried (but not fired) white glaze.

Unfortunately the only source I could find is a German documentary without any subtitles, but starting at 28:10 it clearly shows a potter applying different patterns by sponging pigmented engobe onto unfired clay items.

She explains that she made all of her sponge stamps herself by drawing a motif onto a fine sponge and either cutting the excess away with nail scissors or burning fine lines into the sponge with a soldering iron.

To apply the pattern, the sponge has to be damp. The clay item is covered with a first coat of engobe. After the first coat dried, the sponge stamp is dipped into a very shallow pool of engobe and then stippled onto the clay item.

You won't get perfectly crisp lines with this method, but especially the bottommost picture you posted looks like it was sponged. You can even see a very slight sponge pattern in there. All of the other tiles have very smooth lines and are most likely hand painted, but I can imagine that you can stamp a guiding pattern onto the tile and then follow that pattern with a paint brush.