Thomas Jefferson Papers

Enclosure: Richard Randolph’s Directions for Making Cement, [ca. 10 April 1822]


Richard Randolph’s Directions for Making Cement

[ca. 10 Apr. 1822]

Spread four measures of the powder upon a wooden floor, from six to ten or twelve inches thick. Sprinkle one measure of water equally over the surface. turn up the bed and mix it carefully, so as that the whole shall be equally damp or wet, then heap it up into a compact mass, and let it lie covered in a damp shady place or cellar two or three days; Then spread it on the same floor and sprinkle on sparingly as much water as will barely be percieved, and commence beating with any convenient wooden beaters, the mass will be very refractory at this moment, but by the continued, and all important operation of beating, it will become tough like putty, it now requires perhaps not one half as much water to be added, as when the powder was first laid down; Nevertheless a sufficient quantity of water must be applied, and it will depend in a great measure on the degree of beating, the more beating the less water; and the stronger will be the mortar. Whenever it is to be used observe that it is to be immediately preceeded by beating until in a tough and plastic state, like soft putty. The proof of its being in good order will be shewn by its exudation of the water. The stone or bricks on which the mortar is to be laid must be clean, and thoughrouly drenched with water. It is best at all times to prepare the mortar in a shade or cellar as above stated, and if the masonry be excluded from the sun a few days the better. The slower the drying the more solid the cement. Unlike Parkers Roman1 cement you may take any reasonable time for operating. When delayed it will require repeated labour to bring it into order, and longer time to set. In all cases allow not2 less than ten to fifteen days before the water is let on your work, and if convenient still longer. persons unused to work this mortar should take care to trowel it well, press it on firmly and finish the joints nicely and smooth.

MS (MHi); in Randolph’s hand; undated.

1Word interlined.

2Randolph here canceled “mor.”

Index Entries

  • building materials; cement search
  • building materials; cement, Roman search
  • cement; R. Randolph’s Directions for Making search
  • cement; Roman search
  • Parker, James; and Roman cement search
  • Randolph, Richard; and cement search