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I mortared my first bricks last night (pairs together, for later transport to the hearth) and then the first courses today. I used Lars' 6:4:2:1 recipe with about 4 to 4.5 parts water.
I have four questions: behavior over time, recipe, sand, watered consistency.
First, after twelve hours, and again this evening (about twenty-four hours) -- admittedly not very long yet -- the mortar seems very tacky and small globs break off easily (not chipping like old concrete, but like dried glue. Despite extremely ginger care when transporting brick-pairs to the hearth, admittedly a few were abused and easily fell apart...which I then bar-clamped together and left to sit, although I'm not sure if a break after twelve hours can simply be pushed back together or if it is too late at that point.
Question one: is this behavior from the mortar acceptable? I thought it should act like concrete and be impressively hard the next day. Admittedly, numerous posts on FB confirm that this might be okay, so I'm trying not to worry about it, but it seems a little odd to me that is stays soft for so long.
Question two: There seem to be almost as many recipes as oven-builders. I am NOT asking which recipe people blindly recommend, FB already has no shortage of such posts.
What I would greatly appreciate, however, is an understanding of what effect variations of the recipes should have. For example, Lars' increased the fireclay and decreased the lime relative the James'. Many other recipes do something similar. What does each change do? What does increasing the fireclay do? What does decreasing the lime do? Many recipes increase the sand. Some completely dismiss lime entirely. How should these changes affect mortar? I could experiment, except that I wholly admit I don't even know what to look for, which makes "playing around" rather unproductive. Experimenting is only useful if you know what you're shooting or.
Question three: I bought the white silicate sand available at Home Depot (100 Lb. #30 Silica Sand - 362201999 at The Home Depot), image attached (the image shows "settled" sand, the smallest grains after shaking it level. There are slightly larger grains below the surface I'm afraid.). My mortar has a gritty consistency, as one would expect from such sand. I find this at odds with the numerous "peanut-butter" recommendations, although I admit that that is w.r.t. water, not sand. Is everyone's mortar gritty?
Question four: Water. I know the peanut-butter mantra, but I'm not sure I "get" it. The mortar is very unlike peanut-butter due to the sand, so any advice on this topic would be appreciated. What I used today was 6:4:2:1:4-1/2 (sand, fireclay, portland, lime, water). I felt that 4 parts water was too dry and 5 parts was pushing runny...but I just don't know what to shoot for...sigh.
If you read this far, thank you.
Cheers!
I have four questions: behavior over time, recipe, sand, watered consistency.
First, after twelve hours, and again this evening (about twenty-four hours) -- admittedly not very long yet -- the mortar seems very tacky and small globs break off easily (not chipping like old concrete, but like dried glue. Despite extremely ginger care when transporting brick-pairs to the hearth, admittedly a few were abused and easily fell apart...which I then bar-clamped together and left to sit, although I'm not sure if a break after twelve hours can simply be pushed back together or if it is too late at that point.
Question one: is this behavior from the mortar acceptable? I thought it should act like concrete and be impressively hard the next day. Admittedly, numerous posts on FB confirm that this might be okay, so I'm trying not to worry about it, but it seems a little odd to me that is stays soft for so long.
Question two: There seem to be almost as many recipes as oven-builders. I am NOT asking which recipe people blindly recommend, FB already has no shortage of such posts.
What I would greatly appreciate, however, is an understanding of what effect variations of the recipes should have. For example, Lars' increased the fireclay and decreased the lime relative the James'. Many other recipes do something similar. What does each change do? What does increasing the fireclay do? What does decreasing the lime do? Many recipes increase the sand. Some completely dismiss lime entirely. How should these changes affect mortar? I could experiment, except that I wholly admit I don't even know what to look for, which makes "playing around" rather unproductive. Experimenting is only useful if you know what you're shooting or.Question three: I bought the white silicate sand available at Home Depot (100 Lb. #30 Silica Sand - 362201999 at The Home Depot), image attached (the image shows "settled" sand, the smallest grains after shaking it level. There are slightly larger grains below the surface I'm afraid.). My mortar has a gritty consistency, as one would expect from such sand. I find this at odds with the numerous "peanut-butter" recommendations, although I admit that that is w.r.t. water, not sand. Is everyone's mortar gritty?
Question four: Water. I know the peanut-butter mantra, but I'm not sure I "get" it. The mortar is very unlike peanut-butter due to the sand, so any advice on this topic would be appreciated. What I used today was 6:4:2:1:4-1/2 (sand, fireclay, portland, lime, water). I felt that 4 parts water was too dry and 5 parts was pushing runny...but I just don't know what to shoot for...sigh.
If you read this far, thank you.
Cheers!
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