what type of mortar mix should i use for a
· 4 to 1 mix is far too strong. a 6 or 8 to 1 with an added 1 part lime is perfect for stone. in your case i would go for 6 sand, 1 cement, 1 lime. make your mix stiffer than brickwork mortar and keep your joints as small as possible, fill all joints as you go. at the end of the day scratch off the joints flush and brush with a soft brush.