In the case of emulsion mask, a layer of high-resolution photographic emulsion coats the glass plate. Optical exposure and development causes parts of the emulsion to become opaque, forming an image of the pattern. These types of masks are inexpensive to make, but have poor resolution and are not nearly as robust as Cr masks.

There are two considerations of the glass out of which the mask is made; the thermal expansion of the glass and its transmission at the exposure wavelength. Thermal coefficients for different types of soda-lime, borosilicate and quartz glass are 9.3 ppm/°C, 3.7 ppm/°C and 0.5 ppm/°C respectively. The worst case here is soda-lime glass, which gives a 1.2 µm change across a 5 inch mask for every 1°C variation in temperature, but we still use soda-lime in most cases because it is much cheaper. Thermal effects can be limited by using a temperature compensated environmental chambers. Borosilicate glass is usually used for masks made on e-beam tools. Since the masks are exposed under vacuum, heat is not transferred as readily, so a lower expansion glass is desirable. These masks are about twice as expensive as soda-lime.

When the transmission properties of the various types of glasses are compared deep UV exposures require quartz instead of other types of glass, because glass begins to absorb strongly at wavelengths below about 350 nm. However, quartz masks are several times more expensive than glass.