Holbein waterbrush is my favourite of all the waterbrushes I've used. It's not perfect but I feel it's better than other brands.
It's a rather long waterbrush with a body that can hold more water than other waterbrushes. I can still fit it inside my pencil case so that's a plus.
At the top is my well worn Holbein waterbrush. I've used up quite a lot of waterbrushes over the years.
Their bristles tend to wear out quite fast and I would recommend getting at least two of these, one as a backup, when you're outdoors. I still use my worn out waterbrush, not for painting but to clean up my palette after each use.
The bottom one is a new one I just bought. Holbein waterbrushes come in two sizes, the large and medium. I love the large one because the bristles are longer, about 1.6cm.
A waterbrush is a very convenient tool to bring around and use. If I bring a normal brush, I would have to bring an extra bottle for washing the brush and water supply.
The bristles are made of some white-coloured synthetic material. With usage, pigments will stain the bristles so don't be too caught up with getting it perfectly clean. When it's new, it tapers to a point and when worn, the bristles will start to flare outwards, and that's the time to get a new one.
You can stick the cap to the back of the body.
Here's how it compares with other waterbrushes. From top to bottom, we have Sakura, Pentel (Kuretake), Derwent and finally the Holbein. Holbein has the largest water capacity. I would sometimes squeeze water out and try to shake the pigment off before cleaning (wiping) it with tissue. After that, I can use the waterbrush to pick up new colours again.
One of the challenges of using a waterbrush is unpredictability of the water flow. Actually, water is always flowing so you've to take that into account when painting. For example, you may want to use more pigments because with each dap, you add more water and dilute the colour mixture.
In the test above, I compared the Holbein waterbrush with a normal sable brush. It's so much easier to create an even flat wash with a normal brush. With the waterbrush, the body will keep on supplying water even if you're not squeezing it. So it's challenging to control the water flow. Creating a gradated wash is easier than a flat wash.
Below are some sketches I painted with the watebrush. You can click on them to view the larger image.
In real life, it works well for me most of the time except when I require a totally flat wash. There are techniques to create flat washes with the waterbrush, and that usually involves pre-mixing the colours on the palette rather than on the paper. Other times I would hold the waterbrush with the bristles up and body down to prevent water from flowing.
Here's a close up to the area just above the front wheel. I wanted to create a flat wash but you can see the gradation caused by excess water.
Waterbrushes are more convenient for sketchers who are always on the go. It's great to use for journaling and sketchbooks, outdoor usage. It's also for those who like to bring as few things as possible when sketching outdoors. They are good for holiday sketching and I would usually bring a few so that I don't have to refill them often.
Nowadays, I prefer a normal brush rather than waterbrush even when sketching outdoors because because I like to have more control over the amount of water I apply.
If you want to get a waterbrush, I would recommend the Holbein one over the other brands.