Watching seasoned masons string out mortar makes you think you can just scoop and flick without a second thougth. Spent half of Saturday dropping wet mud straight down into the cores and all over my boots trying to butter the face shells properly. The trick I finally picked up on was mortar consistency and how I loaded the heel of the trowel. Once I backed off the water just a splash to keep it from slumping and stopped overthinking the wrist snap, the ribbons laid down clean on both edges. Setting the next block down into the bed joint felt night and day diferent—one firm press and it seated dead level. My forearms are completely shot today, but looking at a clean four-course run with even joints instead of mortar oozing everywhere feels damn good.
Spent the weekend laying CMU and finally got the mortar spread down
Oct 07, 2026
Last reply: 3 days ago
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I fought that exact battle last summer building a 40-foot run of 8-inch CMU for a raised garden bed. I kept mixing my Quikrete Type S way too wet thinking it whould give me more working time in the sun, but like you saw, it just slumped straight into the cavities and turned the whole footing into a soup bowl. What ended up helping me alongside stiffening the batch was dumping my cheap big-box trowel for an 11-inch Marshalltown Philadelphia pattern. Having that wider heel let me carry a full charge of mud without it rolling off the edges before my wrist made the turn. I also started laying a scrap 1x4 across the center web while spreading just to catch any stray drops before they fell into the bottom of the wall. The forearm pump after your first real run is no joke either. Took me three weekends before my hands stopped locking up around the trowel handle by 2 PM, but getting those 3/8-inch joints consistent without smeared faces makes the ache worth it.
For me, the bed joints fell into place once I got the mix right, but the vertical head joints were what kept kicking my tail. Trying to balance a heavy 8x8x16 standard gray block on its corner while buttering the ears with my right hand had mud dropping on my boots every single time.
An older mason working down the street saw me fumbling and told me to just stand three or four blocks upright on the slab and butter the ears all in a row before picking any of them up. You just slice a wedge off the board, swipe both ears in two quick motions, and set the trowel down before lifting. It completely saved my shoulders and kept me from having to juggle the block and the trowel at the same time. The whole rhythm smoothed out, and my vertical joints actually stayed full instead of ending up hollow on the back side.
Man I cannot wait to start my retaining wall project next month!! Reading this gets me so hyped to mix my first real batch.
Quick question though that might be totally off-topic—has anyone here ever added liquid color pigment into Type S to get dark charcoal mortar joints? Does adding dye totally mess with the water ratio and slump you guys are talking about, or does it set up just like regular gray mud?
The real trap after nailing your spread is timing the jointer. I'd always jump the gun and strike 'em while the mud was still too green, wich just smeared junk across the block faces and ruined all that clean work.
Gotta wait till it passes the thumbprint test—firm enugh to leave an indent, but doesn't stick to your skin. Hit that sweet spot and the tool just glazes it smooth in one pass. You won't even need to brush it half the time.
Quick update — knocked out the rest of the wall yesterday. Waiting for that thumbprint test before striking the joints was a total game-changer. I definitly whould’ve jumped the gun and smeared wet mortar everywhere otherwise. Head joints got a lot smoother too once I settled into a rhythm. Everything cured up clean and tight. realy appreciate the tip on jointing timing!
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