<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div>Lime terminology is confusing and inconsistent at times. The word "lime" is particularly ambiguous, since it is applied to every stage of the plaster making process, and also to various things outside that process. </div><div><br></div><div>For me, slaked lime means calcium hydroxide. To make lime, limestone, whose chief ingredient is calcium carbonate, is quarried, ground, and heated in a kiln or pit. Quicklime, from the lime kiln, is mostly calcium oxide. The slaking process reacts quicklime with water, to produce slaked lime, mostly calcium hydroxide. As lime plaster cures on the wall, it changes to calcium carbonate. So one could argue that slaked lime is the only kind of lime that is useful for plastering. </div><div><br></div><div>Of course there are always impurities and other minerals in the mix that affect the performance of the plaster, both in terms of both ease of application and in how well it performs on the wall. Hydraulic lime is calcium hydroxide with enough iron, silicon, phosphorous, aluminum, magnesium, and other minerals, that it will set up under water. Some people like plastering with hydraulic lime, some don't. </div><div><br></div><div>Perhaps I am missing the essence of your question, Jure. In general, getting the best, purest, freshest, driest slaked lime will give the best results. The minerals in the limestone used to make the slaked lime can be significant. British plasterers in particular like lime that is very high in calcium. This may be hard to find in other places. A large proportion of magnesium is common in many sources for lime (sometimes called "dolomitic lime"). Limes in Italy and the USA are often high in magnesium, and some plasterers prefer to work with these dolomitic limes. </div><div><br></div><div>Magnesium and calcium react at different speeds in a simple lime kiln, which can result in overburnt or underburnt components in the slaked lime. These can cause problems such as spalling- bits of plaster spontaneously coming off the wall. Slaked lime sold as type S in North America (and Australia?) uses a more complex process in production, which can reduce the underburn/overburn problem. Soaking slaked lime in water for months or years (perhaps mixing in sand to make lime putty) can help correct some lime deficiencies, and improve the working properties of the lime plaster. John Glassford of Australia says that he can get good bagged type S lime in his area. He can mix it with water and sand, and use it the same day. He reports little or no improvement with extended soaking. People in other places report that extended soaking of the lime available in those areas can help a great deal. </div><div><br></div><div>Does any of this address your question? </div><div><br></div><div>Derelict</div><div><br></div><div>Derek Roff</div><div><br></div><br><div><div>On Apr 6, 2011, at 11:20 AM, Sport Hotel, Jure Pozar wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"> <div text="#000000" bgcolor="#ffffff"> <font face="Calibri">Hi,<br> <br> Is slaked lime ok for the exterior plastering or does it need to be a special kind of lime for this purpose? <br> <br> Cheers,<br> </font> <pre class="moz-signature" cols="72"><font face="Calibri">
Jure Požar, </font></pre> </div> ____________________________________________________<br> European strawbale building discussion list<br><br>Send all messages to:<br><a href="mailto:Strawbale@amper....muni.cz">Strawbale@amper....muni.cz</a><br><br>Archives, subscription options, etc:<br>http://amper.ped.muni.cz/mailman/listinfo/strawbale<br>____________________________________________________<br><br><br></blockquote></div><br></body></html>