[Clean Cloth]

Whether you are WFP or traditional.

I ask because I do not use anything sharp on glass, I use a mop/applicator to apply the soapy water and if there is bird poo on the glass I use the end of the mop/applicator to scrub it, most dissolves easily but some is difficult to get off and I end up scrubbing quite hard.
I have been cleaning this holiday property monthly for over 2 years and last time I noticed a collection of scratches on the glass, I noticed them again today and wondered if I did it scrubbing bird poo off.

I suppose you WFP users are applying a constant stream of water maybe reducing the chances of scratching the glass.

[Arnold Palmer]

Not in proper use no.

Had an employee who turned the brush on its side and used the stock. That did it.

[NWH]

I’ve done it years ago when I used to scrub with the end of the applicator,my dad used to scratch em when he used to use a 10p coin lol.

[M & C Window Cleaning]

In my experience, to scratch glass you have to use something as hard as glass or harder. 

So when working with a squeegee you need to make sure no grit gets under the blade or on your applicator especially the ends if you use them to scrub bird poo.
It's not common, but bird poo itself can have grit in it as some birds eat grit to assist with digestion.  So a plastic brush stock can scratch glass if you come across this or you are in the habit of resting your brush or brush stock on brickwork or the ground. 

Aluminium seems to react with glass too. ie; Tops of ladders with no mitts on or low quality squeegee channels.

Rusty scrapers will often scratch glass as well, as iron oxide is harder than glass.

These are just a few things I've noticed over the years.

[Smudger]

yes - as soupy said -  brush was turned onto its side and the corner of the stock used - left a lovely load of scratch marks

Darran

[Clean Cloth]

Interesting replies, thank-you.

I thought I was doing the correct thing with soaking the bird poo and then using the end of the mop/applicator to rub the mess off but I was wondering myself if it was gritty I could scratch the glass.

I have now stopped using this method and soak the poo and use a clean stainless steel blade, flat to the glass and only push once then apply more water, repeat until clear.

This customer has not mentioned it to me, yet, but there is a chance that I caused the scratches.

[M & C Window Cleaning]

In all honesty I think most of us who have been cleaning windows for any serious length of time will have scratched a window at some point but our customers just haven't noticed it.
To the best of my recollection I've only ever been called out to scratched glass once and on that occasion I believe it couldn't have been me.  It looked more like it had been done with a broom handle and as she was in the habit of standing her garden broom on its handle and using it far more regularly than I cleaned her windows, that's more than likely what had done it. I couldn't convince her though.  And I sure-fire wasn't going to pay for something I was 99.9% sure I couldn't have done.

[Clean Cloth]

Yes, many customers will blame the window cleaner if they notice any damage which may have been there before we started working for them.
Quite a high % of my customers do have marks on their glass, I used to point it out to them when I started a new job but some were not interested and others did not seem to like me pointing it out so I don't do that anymore. Either scratches or chips from a strimmer flicking a stone up.

Yesterday a customer with a fairly new conservatory pointed out a scratch on the glass, I had not even noticed it while cleaning it, my heart sank and then I felt it and said I think it is on the inside, it was and I do not clean the insides of their windows. Then they remembered their grand daughter knocked it at the weekend.

[NWH]

Point the imperfections out the builder will hate you make sure you don’t even put a cloth over them first though,walk them round that’s the main thing don’t touch em until Marks scratches have been highlighted.

[jay moley]

People still using razor blade scrapers?

[NWH]

I still occasionally use them like I say on existing stuff COVID signs on doors etc but used properly they should only last on very few doors-windows before needing to be changed and should only be used scraping one way with plenty of solution.,a builders clean should be what it says done by the builder.

[dazmond]

Whether you are WFP or traditional.

I ask because I do not use anything sharp on glass, I use a mop/applicator to apply the soapy water and if there is bird poo on the glass I use the end of the mop/applicator to scrub it, most dissolves easily but some is difficult to get off and I end up scrubbing quite hard.
I have been cleaning this holiday property monthly for over 2 years and last time I noticed a collection of scratches on the glass, I noticed them again today and wondered if I did it scrubbing bird poo off.

I suppose you WFP users are applying a constant stream of water maybe reducing the chances of scratching the glass.

get an unger 4 inch ninja scraper with stainless steel blades.....this is great for scraping glass(one way obviously).....

i doubt you ve scratched the glass scrubbing bird muck off...its possible but highly unlikely(esp if there are a few scratches)...

its harder than you think to scratch glass.....

[NWH]

You’ll never know most of the time you’ll get the blame you are the window man they won’t blame the builder unless there was bad feeling or they didn’t like them.