 Short runs can printed on a proofing press, but longer print runs are carried out on a flatbed machine, where the plate is made square, level and fixed on the bed.The plate is then dampened with a slightly acidic glycerine–water mixture which is selectively absorbed by the different gel hardnesses, blotted before inking with collotype ink using a leather nap or velvet rollers.Best results are achieved with hard finished paper such as Bristol, placed upon the plate and covered with a tympan before slight pressure is applied.