The only art classes I had were during my primary and secondary school. I barely remember any proper art techniques were taught to me. I draw and paint terribly even until today.
I always want to learn drawing and painting, but the adult drawing class is quite limited here or sometimes the time does not match. So recently, I noticed there are some watercolour tutorials for beginners (just fit me nice!) as I was surfing pinterest. So I read up some basic intro and then I found this watercolour mixing chart tutorial video (https://www.youtube.com/watchv=wY45AMXs6V8) that I would like to try too.So, I just grabbed whatever I have at home and tried to learn from there. At this 21st century, you can learn almost everything online!
The video have showed everything so I am just gonna to briefly go through the steps. So, these are the old watercolour stock I have since my secondary school, I guess. I did do some basic reading before I started this out so ya, even it drys out, it is always usable by re-wetting up. So you can also try with your old stock if you have any at home instead of buying a new one. I used normal drawing paper instead of proper watercolour paper.
So first, like how I did, you can draw boxes on your paper like I did, I picked 8 colours so I have a 8 x 8 table here. Next, write the colours you picked on both horizontal and vertical side in sequence you preferred, and then you can start mixing the colour. You should always mix more horizontal colour than the vertical one so that your red-green looked different with your green-red.
For every row, you should also always start with the primary colour before you start to mix with theothers. It is interest to see how the colour changes when you mix them.
I prefer to prepare 7 mini pools of my primary colour (horizontal colour) rather than mixing two colours directly as showed in the video, trying to reduce the times I need to keep cleaning my brushes.
So, after filing up all boxes by mixing the different colours, you now have the mixing colour chart that you can always keep as a reference which to mix to get your desire colour next time. I got a bit distracted so I actually mixed the wrong combination when I am trying to mix sky blue with black. Despite the entire work seemed to be pretty simple, but I did find that the ratio of the 2 colours have to be controlled carefully. Too little make no difference, too much make it the same as the other same combination. In additions, my saturation in colours are not quite consistent too, some looked saturated and some looked quite diluted. Hope that you can avoid some mistakes after seeing the mistakes I made. Happy mixing colours~

