Protecting Glass Surfaces During Construction - Why and How?

It is a familiar scene to window cleaners everywhere. After receiving a request for a post construction window cleaning job and visiting the job site, it becomes quickly apparent that the glass surfaces were never protected by neither the window installer, the general contractor or the various trades working adjacent to glass surfaces. Subsequently the glass has been subjected to every type of post construction debris such as concrete sealant runoff, paint, wood stain, concrete, stucco residue, silicone smears, etc. The expectation of the general contractor is that this construction debris can be easily removed from the glass surface by window cleaners with no possibility of damage.

We should pause for a moment and ask - Why are glass surfaces so often left completely unprotected by the general contractor/builder? Especially since the glass industry has published clear and specific guidelines for protecting glass during all phases of construction?

To quote the second joint GANA/IWCA technical bulletin "Proper Procedures for Cleaning Architectural Glass Products" (01-0116) page 2 clearly states "During all stages of construction the glass must be properly protected from construction debris such as cement, paint, varnish, adhesives and other construction material commonly found on job sites." Why is there an urgent need to protect the glass surface during construction activities? This bulletin goes on to state; "Glass that is improperly stored or left unprotected during construction may result in glass that cannot be successfully cleaned using routine cleaning procedures. In such situations, more aggressive cleaning and restoration techniques may become necessary, such as the use of razor blades, chemical cleaning and/or mechanical polishing. Glass surface conditions that may require more aggressive cleaning techniques would include, but not be limited to, the accumulation of paint, stain or varnish overspray; mortar, concrete or cement splashing on glass; silicone sealants and/or lubricants being smeared or sprayed onto glass and frames; and sealer overspray or run-off from adjacent masonry or stone waterproofing operations. In the process of removing tenacious contaminates from unprotected glass, particles may be trapped between the razor blade and the glass, resulting in fine scratches."

An additional technical bulletin cowritten by GANA/IWCA is titled "Construction Site Protection and Maintenance of Architectural Glass" (TD 03-1003). This publication clearly states; "After installation, special attention by all trades should be given to construction activities in order to prevent exposure of glass in windows, doors and skylights to weld splatter, paint, plaster, sealants, fireproofing, and alkali and chemical attack. The subcontractor, general contractor, or builder should inspect and document the condition of the glazed materials on a daily basis. At this stage of construction, the glazing subcontractor should request, in writing, that the general contractor or builder remind other construction trades of the potential for irreparable damage to the glazed materials and to implement systems and procedures for protection." (Page 3) Another guideline is "Proper protection of glass in windows, doors, and skylights throughout the construction process and the life of a building are essential." (Page 4) Hence, it is obvious that more forethought needs to be put into proper glass protection during all phases of construction.

An emerging technology to protect glass from accumulating tenacious debris on the surface are specialty coatings that can be applied once the glass is installed and then easily peeled off once the construction is complete. Any concrete, silicone caulk, paint, wood stain, particulate silica based dirt (which can cause scratches), mineral deposits from stucco or any other source, concrete/brick sealant runoff or anything else will come right off with the film.

One such product is WindOCoat produced by General Chemical. They specialize in many different products used for protecting different surfaces during construction. This one is specifically for glass. It can be applied with a brush, a roller or an air spray gun. Even the window frames can be protected. This is truly an innovative product.

Some glass surfaces are more prone to scratching if aggressive cleaning techniques are necessary to remove debris from unprotected glass. Thus the specific guidelines;... Protect The Glass! I remember once consulting on a building that was completely covered with a silane based concrete sealant. It couldn't be scraped off or removed with 0000 steel wool. There was an alternative method but this would have required so much time it became a restoration job. If WindOCoat had been used prior to sealing the concrete all that would have been needed would have been to peal the film off and throw it away. There would have been no need to even clean the window after. This product dramatically reduces the need to use razor blades, steel or bronze wool, and or powerful organic solvents. General Chem has developed a cold weather WindOCoat (4930 white) and a warm weather WindOCoat (4880 blue). They also have a WindOCoat 1013 manufactured for Low E glass. Many of these products have been successfully tested and used by IWCA Glass Committee members.

Here are a few questions that I wanted answered. The manufacturer provided the answers.

Q; Will concrete eat through it as it cures and reaches a high pH of 9.5?

A; Most of our coating has a Ph of 8 to 9.5. So high alkalinity from concrete drying shouldn’t cause any issue.

Q; Will ordinary rain water deteriorate it?

A; 4880 tends to hold for 3 to 4 days under a water soak test. So rain will not deteriorate it if it’s raining for three continuous days. It still remains adhered to the surface. Whitening can be seen. But the film stays intact.

Q; What of ordinary paint and wood stain? Silicone caulk? Will it protect against weld splatter?

A; Ordinary paint & wood stain can be made up of a variety of different polymers. For this reason we suggest a patch test. But if the underneath of the coating is thoroughly cured, WindOcoat 4880 can then be easily peeled off. But we still suggest a patch test. Silicon caulk & weld splatter will also come off with the product.

Q; If it is left on for six months will it come off with difficulty?

A; After 6 months, (depending on outdoor conditions), the film can lose some elasticity, but it does peel off. We have performed an accelerated weather test on 4880 with good results.

Q; Does it leave any kind of deposit that is difficult to remove once it is pealed off?

A; It does not leave any deposit that could not be easily removed with water. Even the 4930 cold weather version of WindOCoat, (which is more elastic than the warm weather version), does not leave a deposit that couldn't be easily removed with water.

Q; How much time does it take to apply and remove from a 5 by 5 foot window? How much does the product cost to apply to a 5X5 foot window?

A; Using an airless spray, a 5x5 foot window can be coated within a minute and peeled off in the same time. It requires a pint if you apply it at 3 to 4 mils wet. This can vary as the film thickness varies. General Chem suggests 4 mils wet for easy peel and pliability. One liter will cover approximately 4 square meters at a dry film thickness of 100 microns. Costing will be provided upon request.

Q; Can it be applied to a window that has been treated with a hydrophobic sealant?

A; The adhesion of WindOcoat to a substrate is best when that substrate is free of oil and silicone residue.

Q; Must it be applied at a temperature of 40F and above?

A; It is ideally applied at 50 degrees F and above. The Minimum film formation temperature is 35 degrees F. Obviously warmer temperatures lend to a quicker and more thourough cure.

The patch test should answer any question you might have. If you need to know how easily it will peal off aluminum, PVC window frames, wooden window frames, low e coatings, a hydrophobic sealant, or anything else;... just do the test! If you need to know if it can be degraded by the specific concrete being used on the job or anything else;...just do the test. If you need to know how much of the product it will take to coat a window and how long it will take;...just do the test. Then you will have the answers and the numbers to put together your quote.

General Chemical Corp 12336 Emerson Dr. Brighton, Michigan 48116 USA 248-587-5600

The benefits of WindOCoat are very easy to see. With the problem of scratched glass becoming more intense as time goes by we really do need some innovative solutions. This is one of the very best available right now. But it absolutely must be implemented immediately after the windows are installed in the building or even before installation.

Written by Paul West (Glass Committee Chair)

Kohala Window Cleaning
and Henry Grover Jr. (Glass Committee Member)

Glass Smart Consulting

IWCA | 7918 Jones Branch Dr, Ste 300 | McLean, VA 22102 | 800.875.4922
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