INTRODUCTION	LESSON 1	LESSON 2	LESSON 3	LESSON 4

 Traditionally a great number of different lime qualities were available varying from hydrolytic to non-hydrolytic qualities.  Today only the two extremes of natural limes are on the market.  Hydrolytic lime, or XHN, which hardens with water due to it's high content of calcium silicates.  On the other extreme air drying lime, CAEB, which is obtained by burning very pure lime stone, hardens by binding it's high content of calcium hydroxyde with carbon dioxide.  The first is a rapid process occuring in the order of hours, while the later is slow, taking days to month.  Traditional limes are positioned between the two extremes and a good combination for course masonry work allowing for solid layers of up to 2.5 cm is obtained by a 50:50 mix consisting of one part CAEB, one part XHN, 5 parts sand and about 1.6 parts of water.  A very detailed book on this matter has been published by the school of Avignon, "Techniques et Pratique de la Chaux, EYROLLES, 1995 (ISBN 2-212-07216-3).

• It is important to work with clean, dry materials and the sand (0-3mm) must be stored in a dry place.  The CAEB can easily be stored by placing the paper bag in a plastic bag and even XHN will last a year if stored wrapped in a plastic bag in a dry place. I only use drinking quality water from the tap.
• One part CAEB and one part XHN are measured in and premixed in the tumbler.  Be careful as CAEB is very basic and highly aggressive to the skin and gloves must be worn at all times.  There are special oils and greases existing to protect the skin.  I also immediately leave the mixing room or wear a dust mask in order not to breath in the dust while tumbling the mixture.
• While the limes mix I catch the 5 volumes of sand and add them to the tumbler one by one.
• After about 5 minutes dry mixing I add the water in small portions, while observing the consistency.  I continue the tumbling for 5 more minutes. 

• I usually pull pour out rather small portions of the mortar which permit easy work up and transport.
• As the lime mixture is poorly compacted by the tumbling process I re-compact the mixtures by hand.  Small portions are lifted out and projected back into the mixture and the mixture is worked at until a pudding like consistence is achieved.  The same compacting process is done when applying the lime mixture by projecting it with the cuff or stuffing it into the holes between stones using the gloves.

•  To finish the seals around the door frames I normally start from the top using the larger and the small cuffs to squeeze the mixture into the interstices. I never pull down the tools to straighten the seals as I try to reproduce as close as possible the original seals which are still around on these old buildings.  This layer of lime adds to the mechanical strength of the binding and protects the polyurethane seals of the doorframes.

•  The door threshold of the doors were in several cases missing all together and had to be rebuilt using lime stones which were recuperated on the site.
• The first step is, as already mentioned, to clean out the opening down to the foundation (if there is any - otherwise one has to build one up).

•  It is important for this work to have a collection of lime stones and I usually arrange the special shapes like plates, cubes, rods, wedges, spheres, and so on.  I also arange a board loaded up with splinters which are used to fix the stones in place.
• It is important to wet all stones which come in contact with the lime as dry stones would pull the water out of the mixture thus preventing the lime mixture from binding to the stones.  I use a bath for this and  I spray larger blocks and the static parts of the wall.

•  I normally start out searching for at least two blocks which already fit nicely into the hollow between the foundation and the door frame.  It should thus be possible to stand on the frame without breaking it.  
• Slight reworking of the stones using the granite chisel is often necessary at this point in order to allow for a fit.
• The blocks are  pulled out again and reentered after putting lime on their seats.
• The blocks are then fixed with chisels which I hammer in and lime mixture is stuffed in to fill all interstices.
• It is important to get tight and regular fits of the stones when reproducing old walls.  In order to learn the technique I mounted several dry walls.  After some time one develops a feeling for the forms and often spontaneously grabs just the right piece.  I personally learned a great deal about these walls when I hand dismantled several walls which have been destroyed by the fire which had destroyed the commons building at Epanvilliers.
• The following pictures show step by step approach of how a door threshold is being rebuilt in a traditional fashion with lime mortar.