[Jeff Brimble]

John I dont think they are "dust" spots I live in a very rural area and even on calm days or at night in low  humidity, the phobic glass can still dry spotty.

[JohnL]

Like you I too live in a rural area and recently the farmers have been grass cutting and turning over the fields so there is a lot of dust everywhere so much so that on windows I did early this week the sills are covered with dust already. 

I am intrigued by the phobic glass reference though. Do you believe dust spots appear more on this type of glass - and by phobic - is that the stuff that does not sheet because I notice the dust spots do appear more on the non-sheeting type of glass.

[Jeff Brimble]

I understand about the "farmers" dust but its not the norm. As a generalisation I dont think the droplets of water do absorb enough mineral (tds)dust from the air to make the spots that give us the problems on Hydrophobic glass.

The Hydrohillic (water loving)sheeting glass gives no problems and is quicker to clean using 1/3rd less water on regulary cleaned windows.

Yes the problems are always with the droplet forming hphobic glass. However after many years I am still at a loss as to what causes it, except to guess as I mentioned earlier that maybe the water is not filtered enogh. If there is zero wind where do the milky white spots come from ?

Note that the phobic glass breaks down into 2 further types- one that tends not to  spot and one that does.

I remeber some years ago when I started that there was one paticular series of anticyclones that where picking up dust from the Saharh and also Spain, It nearly drove me bonkers because the glass and cars literally overnight had a thick deposit of this yellow and orange sand that turned to a milky paste much like the farmers dust you refered to, the resulting "soup" took several cleans to remove, and just when I got around my round another anticyclone came along and did it all over again.

[john tomkins]

Jeff, in my post further up, when I clean just the glass its ok, if I go up another 10mm  and include the rubber then the dreaded white spots appear--- loads of em, even after numerous cleans

[JohnL]

yes ok Jeff, I'm sorry but we seem to be talking at cross purposes here.

Whichever glass I am on - sheeting glass leaves droplets as well -  droplets form that once dry form perfect droplet shapes made entirely of dust. You can put paper on them and they transfer as shapes made of dust.

Spots to me are different. They are just spots, nasty little gritty critturs that take a hell of a lot of rinsing down and I think they come out of the edge beading  of the windows.

But it is funny I have not noticed white spots.

Oh, and I dont mind warm weather but I prefer not having the Sahara dust storms back again! 

[neil100]

If spots are left in a vertical line, then its due to the rubber seals not being watertight.

If their are a few splattered around at the top of the window then you have contaminted your brush breifly.

Some customers sometimes complain of spots whilst the window is still wet.

And some frames or windows just dont like wfp.

Nel.

[Moderator David@stives]

Just see it as a wake up call.

I got complacent and speeded up , therefore I left spots.

I slowed down and now the spots are gone.

Now the bad weather has gone and the sun is out , it is now time to slow down.

Dave

[Jeff Brimble]

Aye Dave, its a bit like the Tortoise and the Hare story.
Its sooo easy to go too fast. The pole almost demonically takes over your personality and commands you to go faster. 

[neil100]

Dave

I have gone the other way round. I was a lot slower cleaning the windows in winter due to the glass being covered in salt. I scrubbed the windows twice then did a double rinse, I had no complaints about spots.

Now the salt as gone and the widows are cleaner between cleans I am back to scrubbing once and rinseing once. My speed as shot up as a result.

Nel.

[Londoner]

Its no good just saying spots and leaving it at that. Spots where? which windows? where on the windows? all windows of just some? big spots? small spots? runs?

Put your Sherlock Holmes hat on and look for clues.  For example, I find that now I am faster I can be doing the downstairs while water is still dropping or running down from upstairs. This was causing spots and runs on the bottom wondows.

Spots can't come from thin air and they can't come from clean water so the answer is there, you just need to work it out from what it happening. 

[Jeff Brimble]

Yes you do need to work out where they come from, each house is different. But...
Quote- "Spots can't come from thin air and they can't come from clean water so the answer is there, you just need to work it out from what it happening"

Thin air     Have been trying for many years to work it out, some (only some) always spot, and I still dont know why 

A lot is to do with faith..... Beginers and doubters.    Clean a window with wfp then blade it so you have a pristine finish. Now squirt some RO/DI water on the glass and watch it dry perfect. Generally proving that its the method and not the water.
But I still dont know why some spot. 
Mind you thats not quite true I do have clue, Its down to a coating on the glass but what that paticular coating or combination of coatings is.. thats what I dont know.

[Pj]

I am reliably informed that glass never actually dries, that is why when you look at a pane of glass it reflects that ripple in it

[Jeff Brimble]

Its a strange phenomomen it appears hard but is soft not a solid but also not a liquid and still flowing internally, Pilks in St Helens(the canteen I think)  have a long pane 26ft installed since the float glass of the late sixties, they measure it periodically. Internally its moving or flowing downwards due to gravity. The top is getting thinner  and the bottom is thickening. 
It holds water but is absorbent. Strange stuff really. 

[john tomkins]

I agree with Vince that you need to work out why a particular window is spotting, I've worked from the bottom up of a problem window in stages, up the glass to the rubber seal and thats where the problems start, glass itself always ok, get to the seal and loads of runs of white spots so in my case its the seals causing problems