Lime mortar

[brian89gp (WavyGlass)]

How to make up your own lime based plaster.

Supplies:
-Type S hydrated lime
-5 gallon bucket
-Paddle mixer
-Strong drill
-Water
-Sharp sand (not rounded river sand)

1. Fill up your bucket at least half full of water, start adding lime and mixing.
2. Keep adding lime and mixing until you reach a constancy somewhere between sour cream and cottage cheese
3. Cover with 1" of water and leave to sit preferably at least a week. The longer the better.
4. Transfer lime putty to mortar tub and add sand. Use between a 1:2 to 1:3 lime to sand ratio measuring by volume. Mix/beat until to the desired constancy, the longer you mix the more workable it will get.

Notes:
-Less then 1/2 full bucket it will be more likely to fling out when you are mixing. I usually fill 1/2, mix, then add more lime and water to have a 3/4 full bucket at the end.
-It is not suggested you add any Portland cement to the mixture unless it is on a 1:1 ratio with the lime (equivalent of Type N mortar). There have been a few studies that have found that any amount of Portland cement less then that will cause a weaker bond then just using straight lime. (will add link once I can find it again)
-Consider adding a pozzolan if you are looking for a faster set, brick dust and fly ash are two common pozzolans
-Don't let your lime putty freeze

[HB2]

great tutorial - one small point to make about portland cement -

Portland cement is bad for masonary structures that were originally constructed using lime mortar. Portland greatly decreases the moisture permeability of the lime mortar, forcing moisture to find other ways out of the building ie., through masonary units causing spalling or through wood trim, causing paint to peel.

Lime mortar acts as a wick to keep moisture out of the wall / building. Portland also releases salts into the surrrounding area when it gets wet and the recrystallization of the salt destroys the lime mortar it comes into contact with - this acts on the structure in a way that is similar to the freeze thaw cycle.

[brian89gp (WavyGlass)]

Many thanks to you HB, it was your tutorial that I followed the first time I made it.

Is there a shelf life on lime putty?

[Texas_Ranger]

I think that depends on the storage conditions. I had some in an unopened plastic bucket (probably up to 15 years old, PO leftover) and it didn't work at all, just dried instead of curing properly.

[Scott S (WavyGlass)]

Anyone know a good place to get Type-S lime? Never tried and not sure where to start.

[mjt]

Anyone know a good place to get Type-S lime? Never tried and not sure where to start.

I've been poking about because I have a little parging repair to do in my basement. From what I can tell, this seems to be the right stuff:http://www.hedbergaggregates.com/product.cfm?id=859.

I found this by googling for masonry suppliers in my area.

[Sow's Ear Mal]

Hello, I'm new to this forum but it looks great! Re Lime mortar: I'm in Ontario, and I'll be repointing my stone house this summer, 1 white portland, 1 type S lime, 6 sharp sand. I've been researching this, and I noticed there's no mention here of hanging wet burlap over lime mortar to keep it from drying too fast (that, or frequent misting with water) Can anyone comment on this, whether it is a necessity? Thanks, Mal

[Texas_Ranger]

On walls that get direct sun it sounds like a great idea! After all you definitely want your repointing job to last another 100 years.

[lupinfarm2012 (WavyGlass)]

Hi Brian...I have a source for Natural hydraulic lime ( 3.5). Could I use this? how does it differ from
Type S hydraulic lime? Would I mix it in the same ? ratio as per your recipe?
Oh and I should add that I am using this on an interior wall. Although from what I have read it is
okay for general use outside except in areas of extreme weathering like chimneys and foundations.
Please correct me if I am wrong.
The Natural Lime mortar that I am looking at buying is from Singleton Birch of the U.K.

[lupinfarm2012 (WavyGlass)]

I found this really neat blog all about the different hydraulic lime products and their uses. Don't know if this
is the correct place for this but here is it is:
http://limemortar.co/hydraulic-lime/