Li, you're from our neck of the woods, the problem is that we have pretty hard water on the south coast.A Bit of background on the watermarks, it's a long answer so stay with me:
TDS are the total amount of charged ions, including minerals, salts or metals dissolved in a given volume of water. TDS, which is based on conductivity, is expressed in parts per million (ppm).
For car & window washing, the lower the TDS level the better, a reading of 0-8ppm will give you a fantastic spot free finish (even in direct sunlight, but assuming you've not let the shampoo sit on the car), 8-15ppm very light spotting possible, 15-25ppm light spotting likely. - Our standard water in Fair Oak comes in at circa 260ppm - this essentially means g'teed watermarks!Moving swiftly along...lol
I tested our tap water today & the TDS (Total Dissolved Solids) reading came out at 265ppm (parts per million), however connected to my DI Resin Filter it came in at 2ppm (the filters a year old & used for washing & rinsing the cars).
Essentially this means that using the water straight from your tap, even if you tried to dry immediately WILL leave water marks & spotting as some of the droplets dry in the sunshine.There are ways to reduce this, a couple are:
a) Megs Last Touch - used as a drying aid
b) Use a DI Filter
I've tried both & found that the DI filters are best, but they do represent an investment of circa £100 for a refillable one...
Flash had a portable cartridge based unit for sale some time ago, this was my first foray into the DI Resin filter market, although in all honesty I didn't know it at the time. The beauty of the Flash unit was that you can connect it to a standard hose (NOT pressure washer) & the filters last (UPTO) 10 rinses...although the best I managed was about 8...
The Flash product isn't the best out there, but it is pretty good & VERY easy to use
On Ebay they go for about £15 delivered for the sprayer & circa £7.50 per 10 wash cartridge. If you're interested I have a boxed new sprayer & 3 x 10 wash cartridges that you can have for £30.As for the swirls...
Without doubt, no matter how careful you are cleaning your pride & joy you WILL get swirls, alright, some will get it worse than others as we can't all afford the most costly of cloths & utilise the two-bucket-method EVERY time... Real life gets in the way sometimes & let's face it, most of us would rather be driving the car than washing it...MOST of us...lol
I have swirls & my car's less than a year, heck it even came from the dealers with swirls...now there are ways to get rid, but they take time & WILL come back...
So, again a couple of options:
a) Products such as Swissvax Cleaner Fluid Medium, Hard or Pro & others like Megs...many brands have products that can be used by hand, but they take time & elbow grease...
b) Have them buffed out by machine...not really for beginners & can be costly for pads, polish/compound & of course machine...
Option b is the route I tend to use, but you need to be very careful & not do it often...in-fact I'm yet to attack the Camden, but will do over the summer.
Just to show you, here's a shot of the wife's car that we'd had (BRAND NEW) after she drove it through a swirl 'a' matic carwash
She scratched EVERY panel!!!
Here's the final panel shot after spending some time buffing & refining...
It was tough & took a long time to fix the whole car as it was a Toyota Land Cruiser!!! But, it was worth the effort as you can see in the reflection shot...Ways to minimise swirls:
Good MF cloths
Remove Tags (where possible)
2BM (Rinse & Wash, with grit guards)
Try not to use sponges much (grit gets caught in the open pores & drags them across the paint)
Probably BORED you to death, but there are products out there to help...