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Need info on old mortar
Well, since I asked about shellac, I figure that I should ask about old mortar. I am getting to the point where I will need to repoint the old bricks before I put the kitchen together. So from what I read, I will need some sand, portland cement, and hydrated lime. Am I forgetting anything else? A lot of the old mortar is failing due to the previous owners not really keeping up with the gutter/downspout system. I was going to practice with the bricks in the basment, and some of the bricks on the interior before trying to tackle the exterior repointing.
The original mortar has a lot of beach sand in it, and I have been able to find some sea shells in there. I am not too worried about the color of the mortar since the exterior will be repainted in the future. Any help would be great! It would get me another step closer to having a kitchen again :)
The original mortar has a lot of beach sand in it, and I have been able to find some sea shells in there. I am not too worried about the color of the mortar since the exterior will be repainted in the future. Any help would be great! It would get me another step closer to having a kitchen again :)
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Replies to This Discussion
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Permalink Reply by Randall Marder on -
Hi,
Take samples of your mortar to get it analyzed to get the correct mortar mix. One (major) important fact, if you have old sanded brick and you use portland cement or to much portland mixed into your formula you will damage (destroy) the brick. As your house expands and contracts the harder mortar will sand away your brick. Contact your local historical society for recomended labs to test your sample. If you have no one in your area contact the Colorado State Historical Fund for a list of labs.
link http://www.coloradohistory.org/
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Permalink Reply by Martin on -
Thanks for the info! I understand that is it important to use the right mortar. I have seen too many houses in the area have their brick destroyed due to using newer cement. Hopefully the historical society can help me out. I have been in contact with them for some time now, but I never asked them about the mortar. But I will give it a shot. Lab tests sound expensive :(
I am trying to see if I can buy some hydrated lime somewhere around here too. I appreciate the info! Hopefully I can find something out here soon so I can patch up some of the interior walls before putting the plaster/drywall back up.
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Permalink Reply by Randall Marder on
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Here in Colorado the test usually ranges around $250.00. Considering the damage done without the test, worth the investment. You can mail a test sample to (not sure of the spelling) Dick Lipoth. You should be able to find him via the State Fund. I have not seen Dick in a few years, misplaced his phone number. I can get it. Right now I am rebuilding a stone foundation. My mix test, that I am currently using for my project is ;
1 part white portland, 1 part lime, 6 parts sand. See attached picture.
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Permalink Reply by Martin on
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I will have to check that out then. Some of the exterior needs repointed, like yesterday.. so I will have to do something about it this summer. thanks for the info! Where did you find the hydrated lime at?
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Permalink Reply by Randall Marder on
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The lime is type S. I was surprise that Home Depot had it. Any brick supplier will also have it.
if you have the time check out my work. www.rmdesignconst.com
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Permalink Reply by Martin on
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I wanted to ask about the monkey juice stuff you have on your site. Could you use that on a floor? It would be for a bathroom.
I am going to check out Home Depot and see if I can find some of this lime. I figured a brick supplier may have it. But I do appreciate the info!
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Permalink Reply by Randall Marder on
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No Monkey Juice is for walls and furniture, to soft for floors. Try Duraseal Oil base floor finish. Nice stuff. Here is a repointing formula that is common 6 parts sand 2 parts lime 1 part white portland cement. First mix dry than add water
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Permalink Reply by Martin on
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I will have to check that duraseal stuff out. We are running out of time to really refinish the bathroom floor before we make it into an actual bathroom (it is a bedroom right now). I may just repaint it.
I looked for the lime at the only local home depot. My next shot will be at a place that sells bricks and stuff. Thanks for the formula!! I am not too concerned with trying to match the mortar color since it will be painted over, or it will be covered by plaster.. so it may make things easier.
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Permalink Reply by Martin on
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How about the stuff on this website http://www.palimeworks.com/lwus/default.asp?page=ecologic.html. They have some stock colors and the lime/sand/concrete is already premixed in a bag. I guess they use it to restore old buildings. I may give it a shot since it is 18 bucks per 35lb sack, and I could try it out on some of the bricks that need repointing on the interior that will be covered up by drywall/plaster.
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Permalink Reply by Craig Talley on -
Do not use Portland Cement on historic masonry! It will destroy the weaker materials around it over time.
Suppiers:
PA lime works, Andy DeGruchy
Virginia Limeworks, Jeff Price
The lime is not Hydrated but rather a Lime putty made from calcined limestone. It varies from Butter joint formulas for fine joints on face brick to coarse sanded Natural Hydraulic Lime for foundation Stone work.
And I do testing of old mortar in the course of my trade as a Historic Masonry consultant.
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Permalink Reply by Randall Marder on
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Just for the record, the formula I shared was for a stone foundation and should not be used for soft sanded brick
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Permalink Reply by Craig Talley on
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I still would have to not approve of that mix, the majority of builders and too many people well versed in other disciplines of the restoration science and arts do not understand the use of OPC (ordinary portland cement) as being a detriment to all masonry. It matters not if its faced sandstone or split granite and basalt. Even the understanding of old beehive kiln bricks is not the point here. The mortar must breathe, not interact with silaceous materials in the substrate, react and raise mineral salts, ACR, ASR, and most of all be the sacrificial element in the longer timeline of the sustainable restoration practices. You can always patch up lime putty in 30 years but refacing a stone or a section of bricks is expensive if not impossible if materials cannot be scavenged or made to replace.
Your formula exceeds type N mortar 900psi and actually is what we call foundation mortar type M 1200psi for modern block and face brick.
Stone over time becomes friable exposed to elements, freeze thaw, organic colonization, and water percolation.
My house is 1870 vintage field stone and its a proving ground for every well meaning mason in 100 years of history and the only work that has been done that is acceptable is type O mortar at 600 psi.
There ae countless welsh cottages in the UK all the way to castles in Europe that prove Natural Hydraulic lime and lime mortars are the appropriate historical mortar in all cases.
You also have the option of purchasing Jahn M100 pointing mortar from Cathedral Stone.(cathedralstone.com) Unlike the repair mortars you do not have to be certified to buy it and install it.
It's a Pozzolonic mix that has the right strength to do the job without damaging the stone and brick.
I recommend to all the readers of this forum that they read and learn the proven methods from the National Park Service preservation briefs. http://www.oldhousejournal.com/notebook/npsbriefs/index.shtml
These are Department of the Interior guidlines that are actually federal building codes under CFR 36. I certify the project to insure that all comply with these means and methods for the sake of the landmark structure.
Martin,
If you are going to use OPC than your formula should be thus; 1 part portland cement, 2.5 parts lime, 9 parts medium bank mason sand. That is weak enough to give way without spalling the masonry and still hard enough to be a good repair.If you need it to be light colored than silica sand and white portland will replicate old butter joint lime.
Better to just buy Andy's pre mixed mortar though as you are not a professional.
send a picture and introduce yourself Andy's email is on the site and he gives free advice along with a great mix.
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