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Masonry: difference between slacked lime and quick lime

1110d's picture

I have a old house and need to have some masonry repairs made to it.  I know for certain that it was built with a lime mortar.  We've tried a few different mixes all using small amounts of mortar and they are too grey.  It's obvious that we're going to need to use a straight lime mortar.  At $750, using a masonry matching service to recreate the recepie is out of the budget for this small job.  The best that I can tell, the old school recipe was to use "slacked lime" as the base and then add sand to the lime.  I'm thinking a recipe of 1:2.5:0 will be close.  the problem is that I can only find slacked lime in Chicago and the shipping is off the charts.  Calling around, I've been told that "quick lime" is the same as slacked lime.  Looking at the manufacturer's website, I don't see the term quck lime, but the product that they are referencing is labled as a "pressure hydrated type S".  Is this the same product as slacked lime?  What about the resting period?  From what I've read, slacked lime would be allowed to rest for 4-6 weeks before use.

Anybody????? (post #206983, reply #1 of 2)


You need to do a little (post #206983, reply #2 of 2)

You need to do a little research.This booklet, The History of Masonry Mortar, is available as an ebook for $6:

How old is your house? Portland cement was invented in 1824 and the first manufacturing plant in the US was established in 1871. If your house was built after 1900, chances are that the mortar is composed in part of portland cement.

I think that the term you are using, "slacked lime," should be slaked lime.