You Can Be a Surface Technician-Consultant

The IWCA Glass Committee has taken on a new project for 2018 called “Window Cleaner Chronicles”. It will be a complete database of glass related surface defects and contaminants that window cleaners see in the field, complete with photos, and a brief description of the field observation. The list of field observations however is not brief. Here is a list the members of the committee has gathered so far.

Rough glass that is extremely prone to scratching, glass corrosion, hard water stains/spots, metal oxidation, ghost suction cup marks, roller wave and other tempered glass distortion, low E corrosion, failed IG unit, weld splatter, sand paper scratches (edges), transit scratches (circular), concrete sealant runoff (silanes and siloxanes), acid etching, pitting from abrasive particle blasting, fish eye, chemical stains (such as bleach and acid residues from pressure wash processes), surfactant residue from pressure washing, artillery (shotgun) fungus, silicone caulk residue, in house scratch removal grinding damage; and post construction debris commonly found on unprotected glass such as paint, stucco, dry-bit, drywall, wood stain, label adhesive, mortar, concrete, dry-vit, adhesive label remnants, labels that don't easily peel off, wood stain, and Minwax.

I am quite sure we all have encountered all of these in our work at some time. Some of these can be corrected and others cannot. Usually the people we work for are completely unfamiliar with any of them. The "Window Cleaning Chronicles" will help us in a large way to educate our customers both current and potential. The intended goal here is to help these ones understand our challenges and the need to hire a knowledgeable window cleaning company that will not cause any more damage by attempting to remove something with the wrong chemicals and abrasives, or something that cannot be removed at all. We can also help our customers with the knowledge needed to get reimbursement for a defective window. Lets look at the list in more detail.

Rough glass; Most times this can be felt with a coin, a dry fingertip, or even a razor blade. This type of surface can also sound like "sandpaper" when a razor blade is used. Which sound can be light or heavy.

Glass Corrosion; Corrosion can look like a white haze. It happens when certain acids contact the glass but are not rinsed off. It can also happen over time when glass is exposed to high humidity. Which can happen when glass is stacked in storage.

Hard water spots; These can form from rain water runoff from leached concrete, brickwork, or stucco. They also result from sprinklers and the garden hose. Which are both fed by ground water systems.

Metal oxidation; Comes from aluminum, iron, or brass window frames. It also results from aluminum screens that oxidize over time. Sometimes only a single year.

Ghost suction cup marks; Result from the rubber cups that the glass techs use to hold the windows until they are set in place. The rubber polymers move into the glass pores and are hydrophobic. They only become visible when the glass surface develops a thin layer of fog.

Glass Surface Science

Tempered glass distortion; Results from a change in the flatness of the float glass plate when it is either hung or passed over the rollers in a tempering oven. This distortion is best observed in the reflection of objects from a good distance such as fifty feet or more.

Low E Corrosion; This usually happens when a first surface reflective low emmisivity coating is exposed to a powerful acid usually hydrofluoric. HF can easily degrade the physical integrity of such coatings without any signs of damage. Then when the window is washed again with the same product, or exposed to a polishing compound, the reflective coating can easily strip off in patches. These usually appear as black patches in the bright sun.

Failed IG Units; These usually start off light with some fogging developing inbetween the two plates. It can be more heavy at certain times of the year depending on the difference in temperature between the inside and outside. If left for many years the water will actually etch the inside of the window unit making it patchy white.

Weld splatter; This develops as the weld and molten metal strikes the glass surface literally melting it upon contact. Usually the splatter melts its way in and remains after as dark spots.

Sandpaper scratches; These happen when painters sand the wooden frames and pay little attention to not making contact with the glass. Hence they leave long scratches that run parrallel with the window frames.

Transit scratches; Happen when anything is moved across the glass usually for the purpose of cleaning it. Sand particles can be caught between the tool used to clean and the glass surface. Such as a rag, terry towel, or even a paper towel. Since the motion is usually circular from hand motion, the scratches are also circular. Most times these only show up in the direct sunlight but if they are severe enough than otherwise.

Concrete sealant runoff; This happens when the concrete, or brickwork is sealed with a waterproofing fluid which is usually based on an oil, silane, or siloxane. In either case the runoff is typically vertical and will bond to the glass in the direct sun over time.

Acid etching; This can show up as a clear rippled (orange peal) effect, clear lines of distortion (banding). It can also show up as a foggy white haze. In either case it is caused by an acid that directly reacts with the glass. Usually it is hydrofluoric acid.

Bleach and acid residue from pressure washing; Bleach can react with certain paints on the building and deposit on the glass. Certain acids such as HF are used to rinse paint especially. This acid will etch the windows leaving a white haze that will not come off. Ceratin surfactants can also leave stains. There are also chemicals like sodium metasilicate which is a very powerful alkali which will leave silicate spots/stains.

Glass Surfaces Science

Artillary (shotgun) fungus; This appears as raised black/dark brown spots/nubs that seam to be cemented to the glass. They do come off easily with a single edge razor. But there is usually a large number of them. If they are found on a glass surface that is prone to scratching the process used to remove them can be quite time consuming. They come from a fungus that lives in mulch. And are actually shot from the fungus at the glass. Find the mulch and you will usually find the spots on the glass.

Silicone caulk residue; This comes from caulk tubes used to seal around the edges of a window pane. It can be applied at the factory or on the jobsite. Either way when it is shmeared on the glass it will cure and literally bond to the glass. As it cures it forms a covalent bond with the glass surface. If you think you have removed all of it hit the glass with pure water or even just soapy water.

Treated Glass Surfaces

In house scratch removal grinding damage; We have all seen it. Those unbelievable deep scratch patches. Most times the original scratches still remain. It would have been best if the scratches were just left alone. This happens too most times when inexperienced people attempt removing hard water spots.

Post construction debris; The list is virtually endless. As given above. The most common which I have personally observed are paint, wood stain, concrete, silicone caulk, minwax, and labels. The most interesting observation for me is the fact that most times the general contractor does not see this as a problem. We are supposed to have a magic wand and just wipe this debris away without doing any harm to the glass. Sometimes this can be done with a razor or a chemical. But when the surface is prone to scratching it is not that easy. Then it becomes a serious problem. Which must be brought to the attention of the general contractor. Again it is for this reason that the IWCA Glass Committee has begun the "Window Cleaner Chronicles". To help us all educate the people we work for.

Written by Henry Grover Jr. A member of the IWCA Glass Committee
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