The Konig uPVC touch-up pen can be used to remove scratches on uPVC window frames. These pens use a highly pigmented, weather resistant, acrylic based paint making them ideal for applying edges and mitre joints on uPVC windows. There are over 20 natural and artificial materials that can be colour matched using these repair pens. To use the pen, you will first need to shake the pen for approximately 30 seconds. Then holding the pen upwards, simply squeeze so that the pen is fully de-aerated. Next turn the pen downwards and gently squeeze until the nib absorbs the paint. Now the pen is ready to to be used. Compress the nib for a steady flow of paint. Each pen is fitted with an angled tip, to make it easier to use.