The actual question is.
Ions are just impurities that exist in any normal water supply and come in dissolved form minerals just like calcium and sodium, when the water evaporates the minerals that were once dissolved in the water are left behind to leave unsightly spots on your paintwork. Water doesn’t have time to evaporate and leave behind the spots, Action normal course is to dry your car with a soft cloth or paper towel. What is Deionisation? This is beyond doubt impractical though, notably on a rather hot day when the sun will dry parts of your car before you get a chance to get to them.
This is done by passing the water through a filter containing resin beads that have a greater affinity for different ions.
a lot of people have reported getting a better lather from deionised water and so use it for washing therefore.
Immediately rinse with deionised water. It’s up to you. Due to the fact that the filter has a finite life and will mostly be able to exchange ions for a particular volume of water, it makes sense to completely use the deionised water for the final rinse as otherwise you will end up changing filters more regularly than you otherwise need to. That said, this involves exchanging negatively charged ions, called cations for hydrogen and positively charged ions, called anions for hydroxyl.
During the final rinse it’s a good idea to notice that the deionised water beads quite readily and runs off the paintwork surface nearly like little ball of mercury.
That’s when you understand to purchase a modern filter. I’d say if you see this after that, you learn the filter is working. You will notice therewith that there’re no water spots but likewise you car has an immediate shine to it. Be careful with this though as the last thing you should be doing to your paintwork is blowing dust and debris onto it which may cause scratches. It is as the resin beads inside the filter start to approach saturation the beading will start to diminish. Think for a moment. One final thing to note.