Mastic, or Mastich Meniscus
paper shaped openings are cut; and the piece cut out is termed the disc, the margin being called the mask. The mask is placed between the negative and the paper, when it is obvious a print will result of the form given by the opening of the mask, and the margin where covered by the mask will be white. The print may be finished off at this stage, or the disc may be carefully and accurately placed over the print, and the margins exposed to light till they darken to the required tint. A good effect is sometimes given to portraits with light backgrounds by printing under a mask, then using a disc and blackening the margin, enamelling the print, and giving the centre portion a convexity, as mentioned under Cameo.
Mastic, or Mastich. A resinous exudation from the stems of Pistacia lentiscus, grown in the island of Scio. It is usually met with in the form of whitish or yellowish-white drops or tears, about the size of small peas. Insoluble in water; almost entirely soluble in alcohol, ether, chloroform, oil of turpentine, and benzole. It is used for preparing certain Varnishes (q.v.)
Matt Paper. Popular opinion, amongst photographers at least, has veered round towards printing papers with a dull or non-glossy surface. Several commercial makes of matt-surface gelatino-chloride paper have been placed on the market but require no different treatment to the ordinary glossy paper.
Matt Varnish. See Varnish.
Mealiness of Prints. A peculiar mottled appearance on the surface of prints, due to a weak paper-sensitising bath; and as this is also the cause of lack of vigour, contrast, and brilliancy, the term is frequently used to denote all these.
Measles. A peculiar defect in prints, which shows, when they are held up to the light, as opaque blotches, which are due to imperfect fixation and non-solution of the insoluble hypo-sulphite of silver. On keeping, these spots turn yellow, due to formation of sulphide of silver ; whence the name, from a fancied re-semblance to the human ailment. (See Fixing.)
Measures. See Weights and Measures.
Melanotype. A term sometimes applied to Ferrotype (q.v.).
Meniscus. See Lens.