I'm tired of baking my chaps in the slow cooker so I tried Dorlands wax medium to matt my oil colours. You certainly obtain a matt finish but I hated the medium as I can't work the paint properly. Of course, wax medium isn't designed to do this so that was my mistake (curses!) And then I tried Spectrum Matt Spectragel. Deep joy. You mix a dab of this stuff into your paint and it dries overnight to a flat, matt finish. It's a very thick gel in the tin but it smooths out and thins as you work it into your paint; it's a bit like using Liquin. Your paint flows and blends beautifully. I've tried it with my regular Winsor & Newton and Schminke paints and these dry matt overnight. I was trying out those Sennelier Rive Gauche safflower oil paints; these are really nice paints and usually dry overnight to a satin finish. With the Spectragel they dried matt in around 4-5 hours. Here's a picture of my palette. The red and the blue on the left are the matt finish, the blue on the right is Rive Gauche Prussian blue without the medium dried overnight. I bought my tin of the wonder gel from Ken Bromley https://www.artsupplies.co.uk/item-matt-spectragel-medium.htm. The bad news is that the smallest size tin they sell is 250ml and it'll cost you over a tenner. But it works. I'm a newbie on this site so here's a newbie's question... How do we get our pictures the right way up? Happy days.