Cob: (no subject)

Sat Mar 8 16:51:24 CST 2003

the lime you want for lime wash and render is non hydrraulic lime putty. 
these limes are usually desdcribed as fat or lean.they are described as fat 
due to theplasticity and workability of the lime putty produced from slaking 
them. Once lime began to be adopted as the principal binder in mortars, 
plasters, renders and washes, the integrity of the structure improved because 
as non-hydraulic lime (calcium hydroxide) cures, it absorbs carbon dioxide 
from the air and slowly reverts back to calcium carbonate, which is more 
resistant to water erosion. The application of a lime wash, often modified by 
the inclusion of water-resisting agents such as tallow, raw linseed oil, 
animal glues, casein and even common salt, has proved very successful in 
further extending the life of lime render. All of the limewash variants are. 
to a greater or lesser degree, sacrificial. Further maintenance applications 
are required at regular intervals, depending on the number of initial 
coatings; the vulnerability of the site, and the quality of both the original 
material and the workmanship. The durability of non-hydraulic lime render 
depends on three factors. First, the quality of the lime putty which needs to 
have matured for at least three months after thorough slaking. Second, the 
aggregate should comprise of a wide range of particle sizes, equally 
represented throughout the range. Finally, the degree of carbonation that 
takes place. This will depend on temperature and moisture as well as the 
ability of the pore structure of the aggregate and the presence of carbon 
dioxide. Rapid drying out in hot weather can produce an early set with little 
carbonation, resulting in a weak render, which will be vulnerable to rain 
erosion. 

example mix
                     first coat :1 lime putty 2.5 aggreate 80:20 coarse 
rockbeare. rockbeare 6mm rounds
this coat is better when it has largish aggregate  as this aids setting and 
bonding
finish coate
                   1 lime putty: 2.5 aggregate
                                                                 hope this 
helps all the best al
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<HTML><FONT FACE=arial,helvetica><FONT  SIZE=2 FAMILY="SANSSERIF" FACE="Arial" LANG="0">the lime you want for lime wash and render is non hydrraulic lime putty. these limes are usually desdcribed as fat or lean.they are described as fat due to theplasticity and workability of the lime putty produced from slaking them. Once lime began to be adopted as the principal binder in mortars, plasters, renders and washes, the integrity of the structure improved because as non-hydraulic lime (calcium hydroxide) cures, it absorbs carbon dioxide from the air and slowly reverts back to calcium carbonate, which is more resistant to water erosion. The application of a lime wash, often modified by the inclusion of water-resisting agents such as tallow, raw linseed oil, animal glues, casein and even common salt, has proved very successful in further extending the life of lime render. All of the limewash variants are. to a greater or lesser degree, sacrificial. Further maintenance applications are required at regular intervals, depending on the number of initial coatings; the vulnerability of the site, and the quality of both the original material and the workmanship. The durability of non-hydraulic lime render depends on three factors. First, the quality of the lime putty which needs to have matured for at least three months after thorough slaking. Second, the aggregate should comprise of a wide range of particle sizes, equally represented throughout the range. Finally, the degree of carbonation that takes place. This will depend on temperature and moisture as well as the ability of the pore structure of the aggregate and the presence of carbon dioxide. Rapid drying out in hot weather can produce an early set with little carbonation, resulting in a weak render, which will be vulnerable to rain erosion. <BR>
<BR>
example mix<BR>
                     first coat :1 lime putty 2.5 aggreate 80:20 coarse rockbeare. rockbeare 6mm rounds<BR>
this coat is better when it has largish aggregate  as this aids setting and bonding<BR>
finish coate<BR>
                   1 lime putty: 2.5 aggregate<BR>
                                                                 hope this helps all the best al<BR>
</FONT></HTML>

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