COLOURLOCK Duller is a dulling agent to reduce the gloss level of Leather Colours applied on extremely matt surfaced leathers, which is especially the case with new vehicle leathers. More info: Add up to 5% Duller to the COLOURLOCK Leather Colour and use as normal. It is also possible to add up to 3% to the Top Coat. However, this can cause a greying effect on dark leathers. For this reason, we recommend adding it to the paint. To reduce the greying effect a max. 3% of Leather Colour can be added to the Top Coat. This product will need to be sprayed using a spray gun. It is suitable only for professionals who repair leather on a regular basis and have experience in spray work.