I often want to put in fine details, define shapes or highlight areas in an artwork. For this I rarely use brushes but use markers, implements with acrylic paint and or I have used paint squeezed out of a plastic bottle with a fine nozzle. But now I have discovered Molotow One4All pump markers which combine all the aesthetics of using acrylic paint with the convenience of a marker pen. They are filled with a hybrid acrylic paint that is quick drying, silk matt and 100% UV and weather resistant. They are great to use, the colours (over 40 in the range plus metallics) are brilliant and they work on almost any surface - wood, metal, leather, plastic and canvas.
When I have been working in layers I often find that the the picture can become a little dull in colour lacks definition and needs a lift in certain areas. The fact that these markers will work over a surface which is highly textured, and add a highlight, (the white, yellow and bright pink are particularly good), is really useful. I tried this out on a pair of canvases that I did a few years ago. I looked at them again and decided that they needed brightening so I used my new Molotow markers. They worked without a problem over the layers of paper, medium, paint and varnishes and made an improvement as can be seen above (top pics are the before).
I was really pleased to be given these markers as a present, as I can see they will become a vital addition to my supplies. I am looking forward to using them for all sorts of things. I believe they are expensive, but they are refillable and nibs of different sizes are available. In the past I have found alcohol markers useful and they are much cheaper, but I find they don't add the vibrancy to the work that the Molotow markers do.