Sand like substance on windows

I have come up against this type of problem twice now. I don’t usually do CCU but some times there is a small reno at a home and I come across a window or two that has what appears to be a sand like debris on it. I soak it down and bring out the scraper, but instantly get a bad feeling. This stuff ain’t coming off with a scraper and if I continue with this method, I’ll do more harm than good.

In both situations the customer knew about the sand like debris and are looking at getting the builder to solve the problem. I’m sure that there are experts here that know what the debris is and how to safely remove it. Even though I’m not looking to get into CCU in any big way, I’m sure I’'l come across this type of problem in the future.

Thanks for any help.

Can you see it? Or are you just hearing it?

Oh you can see it fine. It looks at first like someone has been doing some garden work and flicked dirt on the glass but this stuff does not come off like dirt. It’s fine but it’s on there good. I almost think it would need to be dissolved with some chemical or something. The one spot where I scraped, the glass is now flat and smooth but you can see all kinds of black specks.

The customer said the workers were doing something with a jackhammer and he saw the window getting splattered with something. The only thing is, I’ve seen this before. Looked the same prior to cleaning, looked the same after attempting to clean.

Do you think it could be fabricating debris? What type of siding does the home have?

Was it splattered with concrete, mortar, or the like? If so, you’ll need a phosphoric acid solution to release the sand prior to scraping. Otherwise, you’re pushing the sand across the glass surface, risking (non-fabricating debris) scratching.

I don’t have much experience identifying construction debris, I guess it could be mortar or concrete. It’s only on one window so there must have been something being constructed close by, maybe around the pool.

Please explain this phosphoric acid solution and application. I’ve heard it mentioned many times before but I’ve never heard anyone do a walk through in the different steps of the process.

By chance could it be welding spatter or possibly artillery fungus?

Phosphoric acid is used for the loosening & removal of Mortar,Stucco & Plaster actually loosens the bonding agent in them.With mortar for example its the cement in it that bonds it.

I normally squirt a line or two horizontally across the glass use a hog hair brush to agitate and scrape in a downward motion for the most part. Ialso use a broadknife on things of that nature. We can get into that later.

Be careful when using the acid it can etch substrate’s like stucco below the windows.

Dan Fields uses a “pink soap” for CCU exterior mortar removals labeled Fields Scale Remover. Surtec System, 1880 N. MacArthur Dr., Tracy, CA 95376 / Phone (209) 820-3700 Fax (209) 820-3793, - manufactures it as their product TILE BRITE SCUM AND SCALE REMOVER (AC800000).

With the solution in a squeeze bottle, dispense along the top of a pane and allow to run down covering the glass.

Before it hits the bottom of the pane, use your hogs hair brush to apply your “standard” WC’ing solution while coating the entire pane with the combination of solutions (phosphoric acid and cleaning.) NOTE: a hog’s hair is necessary, due a standard washer sleeve may trap debris and push it across the surface, risking a scratching.

Allow to dwell slightly (depending on severity of concrete, mortar, stucco, etc.) in order for the solution to release any sand. Make sure to quickly wipe any phosphoric acid that flows onto the structure’s surface.

Scrape glass surface (your choice – razor, scraper, sharpened broadknife).

Clean and detail as usual.

This is detailed in Dan’s Construction Window Cleaning Basics video, available at a WC’ing supplier of your choice (or his website:

If it won’t come off with a razor blade or steel wool, my hunch is that it’s “welding splatters”. If any of the subs were cutting stone or metal or doing any welding near the glass, the hot sparks/debris can fly onto the glass and permanently damage it. I’m in the middle of a large construction clean up on a home right now that has some doors that have weld splatters on the bottom half of the glass – the builder wondered how it could have happened – I then pointed out the metal railing about 6 feet away ???
Only option I know of is replacement – I don’t think the SRP polishing system would work with weld splatters, would it?

Thanks for all the replies. I’ll check out the ‘Pink Soap’ solution and video link to CCU.

Good lookin out! That was my initial hunch as well in an earlier post along with shotgun fungus being a possibility.

Not sure about polishing out spatter marks,thats a good question!!

hi am useing a water fed pole system is there a way off remoing sand and cemeant without getting up ladders and useing a sharo blade regards chris c england

What i’ve done with a few CCU’s is give them a “Pre-Rinse” with the WFP to see exactly what’s left on the glass,this may i have a better idea as to the chemicals i will need for what debris remains.

For sand…it shouldn’t really pose a problem although…i would make it a point to really rinse down the glass as much as possible before actually scrubbing it. Although you run less risk of “scratching” with a WFP brush…i have seen crazier things.

Mortar/cement WHOLE different ball game Phosphoric acid would be my first choice(getting up close and personal with the glass affected) apply horizontal squirts across the glass…use a hog hair brush or similar to lather up (making it a point) NOT to let it run down below the window (it could lighten/etch stucco & other surfaces if allowed to dwell too long) A scraper/razor is a must for proper removal…get a waiver signed FIRST!

Mark, I had a job the other day and there was a sand like debris on many of the back yard windows to the house. It was very very fine and while i hated to pop the scraper out i tried a small area and it came off nicely (made a horrible sound though!) Turns out when the guys sprayed stucco on the underside of the huge deck at this house it was windy out (always windy they live on edge of an escarpment) it went on all the windows, some worst than others. Luckily after soaking the glass, scraping, soaking again, final scraping the none final cleaning…it came off perfectly, no scratches or anything.
I’m assuming that the stuff your talking about is not stucco though.

It’s funny that this thread should be brought alive again after so many months because today I saw the exact same thing. And like in the past cases, this house had undergone a recent renovation.

Once again I saw black grain like spots on the glass. Performed a basic wash and they were still there. Pulled out the scraper and tried a small spot and same bad sound. I stopped and felt the spots. I believe this may be caused by welding nearby as someone else suggested. (railing repair or something) Next time I see this I’ll try to have my camera at the ready.

I asked the customer what kind of work had been performed close to the windows (it was on two of them side by side) but they were clueless and not very concerned either. I just left the window as is.

This past Monday I did a condo/apt and the exterior balcony doors had the dreaded black spots. No camera on me, Damn.

Asked the customer about any recent work on the building. “Oh yes” she said, “They redid our railings including grinding off all the old rust then repainting.”

Grinding right next to glass, eh? Now that I think of it, out of the 5 times I’ve seen this, this is the second time a customer has mentioned grinding close to the glass.

My guess would be if…you look real close at other gigs with any type of wrought iron you see similar. Almost every job we’ve done where iron was installed there has been welding spatter.

Only 1 outfit i know here locally these guys have there act wired tight they on more then one occasion have used sheets of plywood leaned up against windows that would be affected by the grinding & spatter.

I mentioned that to them on one occasion,there reply yeah…we had to buy a couple doors about a year ago since then we take precautions.

More companies need to be held responsible for “shotty work” that in itself i feel would cut back on the amount of glass being ruined by those that don’t take the necessary precautions.