Oh, man, I hear this all the time: "If a little mortar is good, more must be better!" Let me tell you-nothing could be further from the truth. I've made this mistake more times than I want to admit, and it always ends in frustration (and a lot of cleanup).
First, let's talk about why bigger isn't better for small tiles. If you use a 1/2-inch square notch trowel for 4x4 mosaic tiles? You'll have mortar oozing out between every single grout line. I did this once-laid mosaic tiles in a bathroom with a big trowel-and spent 2 hours scraping excess mortar off the tiles. By the end, my hands were covered in goop, and I was ready to quit. Small tiles need small notches-1/4-inch V-notch max. Too much mortar just makes a mess, and it can even make the tiles sit uneven.
Then there's thin tiles-like glass tiles or thin porcelain. A big trowel can crack these. Glass tiles are delicate, and pressing 'em down on too much mortar can make 'em shatter. I had a client once who used a 3/8-inch square notch on glass tiles-half of 'em cracked when he pressed 'em. He had to buy new tiles and start over. Total waste of money.
And let's not forget about walls. If you use a big trowel on wall tiles, the mortar will slide down before you can stick the tile. I tried laying 12x12 wall tiles with a 1/2-inch square notch once-mortar dripped all over the floor, and the tiles wouldn't stay up. Had to switch to a smaller trowel and clean up the mess. Not fun.
Here's the truth: bigger trowels are only better for bigger, thicker tiles. For 24x24 porcelain tiles? Yeah, 1/2-inch square notch is great. But for small, thin tiles? It's a disaster. The key is matching the trowel to the tile-not just grabbing the biggest one you see. I promise, I've learned this the hard way so you don't have to.
