The present invention relates to seals which may be used in an image forming apparatus. In the breaker, the piston is multi-stepped to form first, second and third oil chambers between the piston and the cylinder. Also disclosed are methods of detecting a fill level of a flowable product in an aerosol container using a thermchromatic indicator and manufacturing an aerosol container having a thermochromatic indicator. The color of the glow can be adjusted by choice of luminescent material as a design feature or safety purpose. Efficient light emission in the ultraviolet-visible-infrared wavelength range is demonstrated.