Mortar mix came out like peanut butter, now I doubt my whole process

Tried a new lime putty mix on a garden wall last Saturday, followed the ratio to the letter from an old forum post. The stuff just would not stiffen up, every brick slid around like I was buttering toast with a paddle. My foreman took one look and said 'you testing for soup over here?' before I stripped it all back. Turns out the sand I grabbed from the back of the yard was way too fine, and I should've matched it to the cement type. Anyone else ever get caught out by sand grading, or am I the only one who learned that the hard way?

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wilson.jamie8d ago

Did you check the sand before you mixed it or just grab whatever was in the pile? Sand grading is the number one thing that trips people up with lime putty and it's not just about fine vs coarse, it's about how the grains are shaped and how much silt is in there. That fine sand from the back of the yard probably had way more surface area so it sucked up all your water and left you with a sloppy mess. I made the same mistake on a stone wall years ago and my uncle still brings it up at every family cookout. The fix is simple though, always test your sand by squeezing a wet handful and if it holds shape like brown sugar you're good, if it oozes you need to screen it or mix in some sharper grit. Matching sand to your binder is half the battle and nobody tells you that starting out.

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