A retired mason in his 70s told me my mortar was too wet and I finally get why my joints kept cracking
Honestly I was ready to blow him off. I was mixing on a small job in Fresno last month, three houses in a row, and every one of them had hairline cracks running through the joints about a week after I finished. I figured it was the heat or the brick, maybe the sand. This old guy, he laid brick for 40 years before his knees quit on him, watched me for a bit and said my mortar was too wet to hold anything. He said if it slides off the trowel slow and soupy, it's already dead. I tried a stiffer mix on the next house, about like peanut butter, and I kid you not, zero cracks. Then I checked the 3 jobs I did before that with a ladder and found 22 feet of cracks across all of them. So now I keep a bucket of water next to me and barely touch it. Anyone else here learn a basic thing way later than they should have?