The kilns are made with either fixed or revolving retorts.
The appendix de Benedictionibus to the Rituale Romanum contains formulae, often of much simple beauty, for blessing all manner of persons and things, from the congregation as a whole and sick men and women, to railways, ships, blast-furnaces, lime-kilns, articles of food, medicine and medical bandages and all manner of domestic animals.
In practice the proximity to chalk pits or lime kilns, the cost of the lime and cartage, will determine which is most economical.
What then happened was very natural: imitations of the old wares were produced, and having been sufficiently disfigured by staining and other processes calculated to lend an air of rust and age, they were sold to ignorant persons, who labored under the singular yet common hallucination that the points to be looked for in specimens from early kilns were, not technical excellence, decorative tastefulness and richness of color, but dinginess, imperfections and dirt; persons who imagined, in short, that defects which they would condemn at once in new porcelains ought to be regarded as merits in old.
The waste silk is put into large kilns and covered with hot water (temperature t70° F.).