Thanks for catching that. In the first sentence I should have said 2 days for every half inch. I have corrected that. The following two lines: 2 inches thick has four 1/2 inches, 2X4 is eight days, add two or three, cure for 10 to 11 days. 1 1/2 inches thick as three 1/2 inches, 2X3 is six days, add two or three, cure for 8 or 9 days. Is the correct formula.