[TomCrowther]

I cleaned a new customers windows Saturday morning. The house has just been renovated and it was almost a builders clean. Anyway, cleaned the windows twice using wfp and I could still feel dragging on the glass through the bristles. Looking closely at the glass there are loads of transparent spots which I guess came when the new rendering was sprayed on the walls. So the glass now looks really clean from two feet away but isn't.
I tried giving it a good scrub with a soapy applicator but no joy. The only way I could get it off was using a scraper but it's a big five bed house and I would still be there now if I used the scraper on all the windows, as it is all over every window.
So the point of this post is... do the hot wfp users think really hot water would get this kind of spotting off?
Cheers.

[Harry Robins]

 You can use a brick or mortar cleaner such as disclean (there are many other makes as well), it will just fall off.  I've used it many times ( It's an acid) it has always worked very well for me.

[Slash]

When I do a maintenance clean and the builders or decoprators come in to paint the house I simply ignore the paint splashes all over the glass no matter how big or small a mess,however when the custy says you have'nt got the paint blotches off I simply reply that they or the builder will need to pay extra,because the builder or decorator can't be bothered to be carefull why should the window cleaner spend more time getting the paint spots off for the same amount of money you quote on a regular maintenance clean,I always quote 3 times the normal price for this work as it takes 3 times as long.

[Nathanael Jones]

That stuff is completely waterproof, even hot water wouldn't touch it. 

[Harry Robins]

 Forgot to add.  If you do use disclean, dont let it drip on any metal, as it will discolour it.

[TomCrowther]

Thanks for the feedback guys. Will look into the disclean route.

[Small but perfectley formed]

If the walls have been rendered it may be unibond .