Medieval James Himself

Medieval James Himself
Guide at Ozark Medieval Fortress

Monday, January 10, 2011

Shocking Rocks with a Chase-masse

Jan5 (3)   “If the Roman cementorium cement needs the top and bottom of each stone flat, how do you find the stones?”  The answer at the Ozark Medieval Fortress is that all the stones come from the quarry on site.  This was also typical for the Medieval.  The answer also, however, is that the stones are not found “flat”.  Most of the rocks are split at the quarry to be flat top and bottom to serve as face stones, meaning those that show to the outside or inside of the castle walls.  Even guests that are experienced American masons are surprised at the way the rocks are split.  People expect that the rocks will be hit with a sledge hammer or that wedges will be forced into the rocks to split them flat.  Not so. 

During the Middle Ages the French came up with an amazing tool called the chase-masse, which looks like a hammer but is not.  One side is placed against the rock and the other side is then struck with a hammer.  This causes a series of shockwaves to go through the rock and split it.  The procedure is far faster and less work than wedges or carving.  Again, we have to marvel at the intelligence and ingenuity of the people of Europe in the Medieval.

 Jan5 (2) At the Ozark Medieval Fortress in 2010 the quarrymen used a chase-masse from France that was actually found in a Medieval castle.  The problem we had was that we only had one.  They are not readily available or easily made.  If you search the Internet for “rock cutting tools”, which I did, you will only find companies selling chisels, saws, wedges and the like. No chase-masses, except for two companies in France and those have a modern, machined look rather than the look of the Medieval chase-masse.  I don’t know how well the modern ones work because I have not ordered one. Instead, I fired up my forge and made one in the Medieval style.  The difficulty in making a chase-masse is that the rock contact side has to be hard and the hammer contact side has to be soft.  Steel is a funny thing that way.  It can be flexible and soft or it can be brittle and hard depending on how fast it is cooled. 

Jan8 (7)My chase-masse was awesome!  My wife and I, although not professional masons, split rocks in our Ozark creek bed with ease.  My grandson, Christian, took this video.  You can see why the French were leaders in Medieval castle and cathedral construction.




  1. That is so neat that you made your own chase-masse! Will it be used in the castle construction now?

  2. Wow! That's impressive! The video really shows how great a tool the chase-masse really is! Interesting how we think that we are so "modern" yet quality tools like that can now only be found either in France or from you.

  3. I'm into this type of designs cuz they can verily give contrast to rooms or to any designs imo.
    Stone Split Face