if the sun is at the wrong angle (or the right one depending how you look at it!) it will show up squeegee lines and for the want of a better word, smears from using a cloth.
And it matters not a whit how clean everything is.
People talk of WFP leaving spots and so on, well this is what you get with trad.
When the sun is very direct on the glass, you know, fairly low in the sky, it is so bright that every single flaw in the glass itself shows up too, it isn't just the marks left behind from window cleaning.
Clean equipment, good rubbers in your squeegee, a proper window cleaning detergent and so on, all of these things reduce what is left behind.
If you squeegee a patio door door instance, and see that you have left a kick or two somewhere on the pane and then use your scrim or microfibre to dry it off (and we all do), from the inside when the sun is at full on the glass, that rub with the cloth will show up, and as days and weeks pass it will show up more.
I always taught the lads that worked for me to not pick up any kicks they might leave on the glass with a cloth, but to re-wet the pane and squeegee it off again.
But even though you may think it is absolutely perfect, if the sun is low and bright and at the right (or wrong) angle you will be able to see every turn of the squeegee. (along with every flaw in the glass).
I had one pane of glass on a particular shop that I would challenge myself on as at one point in the year, whenever it was cleaned (late afternoon) if the skies were clear it would be an absolute sod to get perfect...in fact I could never get it perfect
When the sun was higher or it was a cloudy day you would swear it was perfection personified...until the sun was at the wrong (or right
) angle!
if you are rubbing the glass with something, the evidence of it will be left behind.
Glass itself isn't perfect it isn't completely smooth for one thing, no cloth on earth is totally clean or fibre free, in use everything we use on the windows wears out, no matter what you use as a detergent, it is still an additive to the water and as such, something will be left behind.
If the surface of glass was utterly flawless it would help, but even the best squeegee rubber will not remove everything.
If you magnify the surface of glass high enough it will appear rougher and rougher, with valleys and mountain ranges and that is part of the reason why glass cleaned with a cloth or a squeegee will not be perfect because you cannot get into these valleys, troughs and mountain ranges to remove all of what is on there.
A forensic scientist would explain it better, but you get the picture.
And WFP doesn't escape Scot free either, although in direct sunlight it is better than trad, as the water dries out it will attract microscopic particles from the atmosphere, and in the conditions where the sun is at the right (or wrong! :
angle you will be able to see spots. but the effect is not anywhere near as noticeable as it is with glass cleaned trad.
To get glass perfect it would have to be washed and rinsed as they do with the glass for double glazing...but even then, the glass on the inside of a sealed unit might be utterly clean, but with the sun just so (I'm getting fed up of using right or wrong
) in the sky, the flaws and imperfections in the glass itself show up...
Ian
