Cleaning concrete off of tempered glass

I started cleaning windows as a side hustle about six months ago. Today I went to look at a house that needs post construction clean. Some of the windows have concrete stuck on them and they are tempered. How do I remove that without scratching the glass? Also, as I understand, you’re never supposed to use a scraper on tempered glass. I really need some advice here. I’ve never done a post construction clean before and I’m wondering if I should bid the job or not

Concrete stuck on tempered glass?

Idk bout you but that’s a no for me dawg.


I Just passed on a job like this a couple of months ago. Don’t forget if there are any pre-existing scratches you’ll get blamed for those as well.
Pass !! Plenty of easier work out there for you. Well when the winter is over that is. Hang in there !
If you do decide to move forward and do it. Have them sign a pre-existing condition waiver

1 Like

Thanks Majestic66. I appreciate the advice. I’m still thinking about it, but I’m starting to lean towards passing on it, unless there is some product that can I can use to dissolve the concrete. There’s quite a bit of windows and several are quite large overlooking a lake. Most of the windows look like it’s mostly dust and dirt, but a couple of the sliding doors had quite a bit of concrete splatter on the bottom part
I watched a guy demonstrating scraping concrete off glass, but that was not tempered glass

This winter is too damn long lol

1 Like

Pass here too, unless there is no other work and you feel sure you won’t get blamed for damage.

1 Like

Thanks for the advice. I have decided to pass

1 Like

There is a product called cement off. Not sure how good it is, or if it even works.
If it’s only those specific doors you’re talking about. Maybe just let them know. I can clean everything else , but I don’t use blades on glass , because they’re prone to scratching.
That would be the easiest way to get cement off blade it . Maybe try this cement off stuff , you can buy a small bottle. I wouldn’t use a blade though.
Let homeowner know all this. You can clean everything , but won’t remove cement from doors . Your willing to pick up a product that might work without scraping. If not leave it in there hands for cement removal.
Some people are ok with that. It’s happened for me many of times. Just need to set that expectation level.


Great Info and a video on Fabricating Debris can be found here: Fabricating Debris - What Is It? | WCR –

Then you should also check this area out for New Construction guidance and videos: Construction Clean Up | WCR –

Both pages have some downloadable forms and waivers you might want as well.


This is a good product -

As @Chris said, Titan Cement Off is really good but I quit doing ti on heat treated/tempered glass. When I did them:

  1. Talk to the customer about the glass and expectations; explaining what is likely under the dirt and concrete will be scratched and get them to sign a waiver after explaining my method in detail. This includes pictures before, after WFP, and after finishing the clean. Make sure you priced it right.
  2. Pictures and making notes beforehand. Double check that you priced it right.
  3. WFP is a Godsend for this stuff. I WFP the thing, rinsing before even scrubbing and then rinse really well after. Make sure you priced it right.
  4. Pictures and notes. Make sure you priced it right
  5. Clean and use Titan or another concrete dissolver. Did you price it right?
  6. Pictures and talk to the customer because the contractor has already thrown you under the bus. Price it right and move on.
    I bring up price because I am usually under what I should have done. New rule, get my price and double it. Take the pictures, then double it again. That is when I tell the customer the price. :slight_smile:

Great suggestions. Thank you guys for taking the time to respond. I really appreciate it. I decided to pass on this opportunity, but I’ll be better prepared next time, thanks to you all

If you do take these jobs on, let the customer know that because the windows were not protected from these kinds of debris during construction or remodel, then to remove harsh stuck on debris there is a very good chance of scratching the glass. Sometimes hosing the whole window off before scrubber and squeegee (or rinse with water fed pole) will remove the loose grit that can get trapped and scratch as well. Construction Cleanups require washing the window 2 - 3 times and some form of scraping, so that is why charging 2-3 times as much as regular clean is the norm. When scraping I try to just do “spot scraping” where I may use the corner of a razor or gentle nudges to the debris in order to remove it with as little risk as possible of scratching. I ALWAYS TALK TO THE CUSTOMER UP FRONT and show them what I am faced with, and let them know I can try or I can leave it because of risk of scratching. Their call.


Garry brings up the real issue, "because these were not properly protected . . . "

“because these were not properly protected by the __________ company (concrete, painters etc) I cannot, it is not possible to guarantee you will have scratch free results (like new results). They should have been properly protected from start to finish”

it’s a because, then issue

the way this response was worded it reminds me of when there’s tape on window film - we tell them what will remove baked on tape will damage the film,
should not have put tape on the film in the first place

generals blame the window cleaner but really it falls on the general for not making sure the concrete guys protected things. window cleaners removing the junk is merely an attempt to have like new results (think auto body shop repairs) to cover for the general’s and contractors error

unfortunately it turns into a “last touched tag you’re it” gotcha issue


This document from GANA supports what you say about protection…

GANA copy.pdf (302.7 KB)


@Matthew Just printed that for my CCU contractors. I have great guys that do a great job but this is now in the folder for clients too.

1 Like

I had a recent storefront with this issue, it was a remodel and there was paint, concrete, and plaster everywhere. I just had them in my SUV from some car stuff I was trying, but I used a plastic razor on it. The plastic acted as a sacrificial material that would take the concrete off without the material hardness to scratch the tempered glass. Not saying that I didn’t just get lucky, but it seemed to work and there wasn’t any scratching.

I would guess - and this is just me spit-balling here with my experience in manufacturing and not tested, proven science - but I would assume one could use something like Muriatic Acid to dissolve the concrete. The acid option would be messy unless you hypothetically could make a sealable tray or a sealed bag option (similar to argon purging the backside of stainless steel for TIG welding).

I would be interested in the remedial actions that can be taken to deal with concrete and similar naissances.

1 Like

Today I used Mean Klean to clean fine concrete spatter off of glass. It worked great. Dissolved the little black bits in 25 minutes or so. “Hey, I’m a frickin genius!” Or so I thought.

When I mopped & squeegeed, I saw that the concrete (or Quickrete or masonry or whatever it was) left tiny pits. From the thrill of victory to the agony of defeat, just like that.

Just thought I’d warn y’all. Mean Klean will get the concrete off the glass without abrasives or razoring, but prepare your client for the possibility of pitting.

Thanks to a video by SteveO, I was texting the builder the whole time and looked like a pro even though it didn’t leave the glass like new.


How long had it been on the glass?

No telling. I’m not familiar enough with the builder’s process to know when anyone would’ve been using masonry products. It was on the interior side, believe it or not.

A bit of Mean Klean leaked through my masking and made the paint on the sill bubble up, too. Good thing the painters were there and I had built rapport with them as a former painter. The site supervisor said he’d take care of it, no charge. I should drop off a six pack for them.

1 Like