Feb: 20. 1809
To form a rough coating or casting, for the out-side of a wall, or even for pillars that will bear all weather--harden by time and last forever, you have only to take sharp gritty sand free from earth, and that it may be perfectly so, put into Tubs or troughs of water, & after stirring it, let the water be bailed off till no particles of earth remain. This done, add no more lime to the sand than is absolutely necessary to Occasion them to adhere to each other, and to effect this, with the use of but very little lime, let the Mortar be made with hot water, and put on by some hands as fast as it can be made by others, and let those employed in putting it on, have hot water standing by them into which they may immerse their trowels, as they spread & Smooth the casting. The casting should be just thick enough to form a Smooth & equal Surface. The best time for putting it on is in the Spring, when there is no danger from frost, and before the Sun is so hot as to crust the outside, before it dries through, or it will crack and peel off as is always the case where this business is improperly done, but if the above directions are attended to, the rough casting will last without crack or blemish, as long as the wall itself. It must not however be brought nearer to the Surface of the earth, than about six Inches, & the intermediate Span should be Supplied by a good painted two inch plank--you may give any colour that you please to your house, by adding a little Ochre to the Mortar. The workman will of course give it the appearance of a wall of hewn Stone, by deviding it with his line & giving it the appearance of such a wall by the proper lines of devision. I am with high Sentiments of regard, your faithful freind & Servt.
DLC: Papers of James Madison.