Colour filters only transmit a certain part of the coloured, visible spectrum, whereby the remaining components of the radiation are filtered out. Colour filters made of plastic film are not heat resistant. Conversely, heat is not so critical for glass filters and, to an extent, they are resistant to temperature change. Absorption filters made of coloured glass attain lower colour saturation compared to interference filters. The colour-filtering property of interference colour filters is not immediately apparent - they do not look coloured.