lay line of mortar on sill
apply mortar to side of block
wipe off excess mortar with damp sponge
Lay the First Row of Blocks
Lay a line of mortar on the sill, using enough so that it will squeeze out when you set the blocks in place (Image 1). Don't apply mortar to the jambs. Set the spacers in place, then set the first glass block in place.
For the next block, apply mortar to the side that will be closest to the adjacent block (Image 2). Again, apply enough mortar that it will squeeze out when you press the blocks together. Repeat the process until you have completed the first row of blocks. Check the row for level and plumb. Wipe off excess mortar with a damp sponge (Image 3).