“Buttering” a brick refers to the process of applying mortar to the end of a brick before setting it into an established row. Properly loading the trowel with mortar is probably the trickiest part of the process. After you’ve managed to do that, applying the mortar to the brick and setting that brick in place will be fairly simple. You may never need to do this yourself but here are step-by-step instructions just in case:
Grab the trowel.
Grab the trowel handle with your dominant hand. Your fingers should curl around the width of the handle, but your thumb should be extended along the length.
Cut a section of mortar.
Using the side of the trowel head, cut away a portion of mortar from a larger pile of previously mixed mortar. Drag this portion away from the primary pile and toward you.
Turn the mortar.
Turn the cut portion of mortar several times using the trowel. After a few turns, the mortar should take on a smooth texture and paste-like consistency.
Slide the trowel beneath the mortar.
Slide the edge of the trowel beneath the portion of mortar, lifting it onto the flat face of the trowel head.
Flick your wrist downward.
While holding the trowel horizontally with the mortar side facing up, flick your wrist and the trowel downward with a quick snap before stopping abruptly.
Grab the brick.
Pick up the brick you want to butter using your non-dominant hand. Tip the brick downward at an approximate 45-degree angle.
Slice the mortar onto one end.
Invert the head of the trowel and slap the mortar onto one end of the brick using a downward motion.
Squeeze the mortar into the center.
Use the tip of the trowel to press the glob of mortar inward toward the center of the brick end.
Place the brick on the bed.
Set the buttered brick down onto a prepared bed of mortar. The buttered end should face the brick previously set on the bed.
Push the brick against its predecessor.
Shift your hand to the non-buttered end of the brick, then push the brick inward toward the end of the preceding brick.
Scrape away the excess.
Slide the edge of the trowel head along the bottom and end joints of the newly set brick.
Tap on the placed bricks.
After setting each brick, tap on the sides and top of the brick with the end of the trowel handle to help settle the brick in place.