Plain old Water

A while back I got chatting to another miniatures painter at a convention and he mentioned using distilled water to mix paints with. I'd never heard of this practice before so asked him about it. He insisted that using distilled rather than tap water was better for diluting and blending with than any other option. He was a little vague as to why this should be the case so I decided to investigate.

Tap water actually varies in quality from one area to another. London (where I live) for instance has relatively high levels of Calcium Carbonate (from dissolved limestone/chalk) in it. This is why kettles get lime scale inside them and why irons ‘fur up’. If you use water to dilute paint for washes you are also adding a small amount of this mineral to the paint. The water evaporates and leaves behind the paint and the mineral. In really ‘hard’ water areas this could seriously affect acrylic paint and can - it is claimed- result in powdery looking deposits on models. I've never seen this myself but it sounds like a logical result when using water with a high mineral content in it.

Distilled water on the other hand has zero mineral content because it is made from condensed water. The process of making distilled water is simple and can be repeated easily at home. Boil water and let the steam hit a cold surface like a mirror or tile. Some of the steam will condense back into water. What’s happening here is the water molecules become a gas when heated but the mineral molecules in the water do not. So the steam is ‘pure water’. This process is called distilling.

Another suggestion that is hinted at on several painting forums is that acrylic paint can 'react' to the chemicals in drinking water, and by that I assume they mean the added Fluoride. None of the people making this claim explain how this process works. There are a lot of conspiracy theories on the Internet about fluoridation of water but I'm pretty sure that the evil hive over-mind that runs the planet didn't decide to add fluoride to our water to thwart the work of model painters using acrylic paint. Nor do I believe that fluoridation is responsible for corrupting our "bodily fluids".

However on the principle that less is more I have started to use distilled water for blending and mixing etc. Its cheep and can be bought at any service station/garage and is even available in supermarkets. I still use tap water for brush cleaning and drinking... although of course I don't drink the brush water. That would just be weird. 

I'd be interested to hear what you use and why, and of course if you can offer up some scientific reasoning behind some of the claims of 'chemical reactions' when using tap water that would be great.