Sunday, April 17, 2011

How To Avoid Using A Razor Blade to Clean Glass PILKINGTON Activ™ Self-Cleaning Glass GLAZING GUIDELINES Pilkington Activ™ Self-Cleaning Glass has a thin, clear, permanent, pyrolytic Titanium Oxide coating on one of its surfaces. The coating has a hydrophilic property with makes raindrops spread out, or sheet, across the surface to wash away dirt particles. It also acts as a catalyst, when activated by daylight, to break down organic dirt into water vapor and CO2 gas. Pilkington Activ glass needs to be glazed with the coating on the #1 (outboard) surface. It should be located where it will can receive daylight because the coating utilizes the sun’s ultra violet light, either direct or diffuse indirect, to activate its self-cleaning action and destroy organic material on its surface. There is sufficient indirect UV light to activate the coating, even on a north elevation (in the northern hemisphere), underneath overhanging roof eaves and behind an insect screen. When glazed beside a light of clear, non-coated glass the Activ Glass will appear slightly brighter. RECOMMENDED GLAZING GUIDELINES Wet glazing tapes, such as “preshim” with a neoprene rod core enclosed in a high viscosity butyl, are designed to remain pliable and flexible over their design lifetime. These tapes may contain a significant percentage of oil that can migrate onto the glass surface. This oil can sometimes be seen on the coated surface and can be difficult to remove without damaging the coating. Silicone sealants can also exude silicone oil or plasticisers while they cure, and long afterwards. These very thin layers of silicone oil are very difficult to remove from glass or coatings. They are usually only visible when the glass is wet, and even then they are only noticeable by the different water droplet formation when compared to clean glass, but they do cover the coating and effectively inhibit the self-cleaning action. ATS-169 2008/05/12 Page 2 Neoprene gaskets are often coated with extrusion oil or a lubrication liquid to assist installation. This will usually be removed during the first glass cleaning, provided the lubricating liquid does not contain Silicone. It is for these reasons that the following glazing materials are deemed compatible with Pilkington Activ Glass. 1. Use a clean, oil-free, dry gasket system against the Pilkington Activ surface Or 2. Use silicone oil free, one or two component, curing, glazing sealants such as polysulfides and urethanes, Or 3. SMX 505 by Soudal Inc. Contact: Mr Glen Kallgren, National Sales Manager. 682 553 1173. gkallgren@soudal-inc.com 8888 Governors Row, Dallas, Texas 75247 Or 4. Manusbond 35MP by Manus Products, 866 Industrial Blvd. , West Waconia, MN 55387 . Contact: Mr. Brian Henjum, Dir. Sales, Tel 952 442 3323 brianh@manus.net Or 5. Sonolastic 150 by Sonnerborn. Supplied by Chemrex, MN . 800 433 9517 (Avoid direct UV exposure) Follow the manufacturers’ recommendations and insure that the sealants have adequate UV and weathering stability. Identifying the Activ Coated Surface The coated glass surface should be identified by the location of a lable on the non-coated glass side. A special hand-held detector is available from EDTM, Toledo, Ohio , tel. 419 861 1030, www.edtm.com to positively identify the coated surface. The fine scale roughness of the coating can be detected by added friction when it is rubbed with finger tips or finger nails. Note: the coating emittance is the same as non-coated glass and so standard Low-E detectors cannot be used to identify the coated surface. ATS-169 2008/05/12 Page 3 Maintenance and Cleaning Activ Glass See ATS Bulletin #166 for details. It is on the web at: http://www.pilkington.com/the+americas/usa/english/building+products/ats+bulletins/default1.htm The information contained in this bulletin is offered for assistance in the application of Pilkington North America Inc. flat glass products, but IT DOES NOT CONSTITUTE A WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. Actual performance may vary in particular applications. [ Home Page | SimPole Brushes | New Products | COXREELS | Fiber Glass Poles | Testimonials | Ordering | Self Cleaning Glass Warning | How To Glass | DI Water | Pole Details | Product Survey | Contact Us | Newsletter | Water-Fed-Pole Links | Blog SimPole ] nformational Bulletins Proper Proced Paul is on the right tract because a lot of new glass out there in not all bad but it does not like razor blades. I manufacture the www.simpole.com which is made out of carbon fiber which is conductive to electric wires. If I warn the cleanlier to keep the pole away for wires that doesn’t make my product defective. We need information or the type of glass and not just say it is bad glass because we can no longer use razor blades. I see windows every day that have scratches on them from razor blades (not from us because we have stop using them and will WFP all new job first.) There is other ways to clean window without razor blades.( WFP- PRESSURE WASHING) If the manufacture does not want us to use them in why should we be so bull headed and tell we know better. They make the glass and if they say not to use razor blades on most new glass out there we should listen to them, It’s their Glass! Ask most of the follow window cleanlier and they will agree that in the last ten years the new type of glass will scratch even without FD problems. Education is the key not always saying my way is best and I be dam if a let an manufacture tell I can’t d razor blade! We'Dew"Windows Inc www.wedewwindows.com "40 YEARS CLEANING WINDOWS" SimPole Inc. "WE USE WHAT WE SELL" www.simpole.com 1-865-256-2225 ures for Cleaning Architectural Glass Products - GANA 01-0300 Download Bulletin in PDF Format (181 KB) Cleaning Glass Gana Web Site. http://www.scratched-glass.net/ Check out the site to avoid scrarching glass. Click on titles to view articles - the Acrobat Reader is required to view some articles. Please note: All comments on this page were written by Gary Mauer. No one should assume or infer that the owners of any other website endorse this website or any of the opinions expressed. Some of the links below lead directly to items on other websites. It is our policy to always provide equally prominent links to the home pages of these other websites. We urge all visitors to follow these document links and to read the entire document cited, and we also urge visitors to follow the home page links in order to fully appreciate the content of the other website. Click here to learn more about this website. IWCA Seminar on Fabricating Debris Awareness - 2006 Dan Fields, a highly regarded expert on the subject, presented a seminar called "Fabricating Debris Awareness" on Saturday, Feb. 18 at the 2006 IWCA Convention in Mesa, Arizona. Purchase 2006 IWCA Fabricating Debris Awareness CD online Everyone with an interest in this issue needs to listen to this recording. This is a turning point in the dialog between window cleaners and glass companies. Double Audio CD. IWCA Seminar on Glass Fabrication & Processes - 2005 The day after a tour of the local Arch Aluminum & Glass tempering facility - during their 2005 convention in Orlando - the IWCA recorded a very interesting discussion about how hard these fabricators worked to produce better quality tempered glass for their customers. During this discussion, these fabricators agreed that an ideal way to check for fabricating debris was to use a razor during regular QC checks on glass exiting tempering ovens. Click here for Gary Mauer's article about the tour & seminar Window cleaners were bussed to the Arch plant one day before the IWCA seminar. The editor of Glass Magazine - Nancy M. Davis - wrote an account of the discussion at the IWCA/Arch tour for the April 2005 issue. In that article, Max Perilstein, the Vice President of marketing for Arch, and leader of GANA’s Building Envelope Contractors division said, “We believe we're doing things the right way.” He advised window cleaners to “Investigate local glass fabricators. Ask if they’re doing the things we’re doing here.” That article was removed from the Glass Magazine website after only a few days. Articles by Daniel A. Fields - WindowGuru@aol.com Fields Construction Services, Inc. 5715 South Front Road, Building B-1 Livermore, CA 94550 - Phone: 925-294-8183 Scratched Glass Seminar Outline of Scratched Glass Seminar presented by Dan Fields at the Window Cleaning Network Picnic in Oconomowoc, Wisconsin, July 27, 2002. This seminar covered the leading cause of glass scratching - defective tempered glass surfaces. "Scrapers don't scratch glass - fabricating debris does." Construction Window Cleaning A Primer; By Daniel A Fields The purpose of this article is to help enlighten general contractors, window cleaners, and other responsible parties in the residential construction industry on how to identify some of the numerous causes of scratched glass. This article discusses the responsibilities of the construction window cleaner, other subcontractors and the general contractor, the major causes of scratched glass, and the possible solutions to this widespread problem. Glass Quality By Daniel A Fields An illustrated essay on tempered glass quality - the origins of fabricating debris, and what needs to be done about it. Article by Gary Mauer Scrapers & Fabricating Debris Issues - Revised 2/23/04 Window cleaners: This article will help you and your customers understand the problems presented by fabricating debris on some heat treated glass, and why you need to have a fabricating debris damage liability waiver signed before you scrape tempered glass. This update contains several clarifications, including the statement that "The incidence of fabricating debris is greatly minimized when temperers adhere to all recommended maintenance procedures for washers, rollers and other tempering equipment." Print copies and show it to builders. Help them realize why they should insist on quality tempered glass - that can be scraped - and why they need to sign your waiver. Builders are encouraged to manage fabricating debris as a manufacturing defect on some of the tempered glass they are getting, and address this issue with their suppliers. Work with them to assure that the uncoated tempered glass you're getting can be successfully cleaned with a properly used scraper. If you can do that, you'll have no more problems with tempered glass damage than you do with annealed. This article may be reprinted and redistributed by anyone who wishes to. Photocopying and fax distribution is discouraged - but only because color photos of glass defects are involved. I recommend printing from the original PDF file, or emailing the file itself to interested parties. Article in the International Glass Review Partnering with the Glass Fabricating Industry This 2002 International Glass Review article by the leading supplier of furnace rollers points out they offer "free seminars to customers focusing on roller properties, cleaning and maintenance procedures, roller refurbishing and regrinding options and precautions, the effects of the plant environment and fabricating practices on tempered glass." They also offer laboratory analysis as a free service to their clients, to properly identify "glass surface conditions or markings". At one point, this article says, "Most often the conditions that appear on glass surfaces during the heat treating process are related to foreign materials that have been mechanically impinged into the glass or that has damage the glass as it passes over the rollers. " An illustrated article from the 2001 International Glass Review entitled, The dynamics of ceramic rollers Operating and maintenance practices to produce quality tempered glass; By Renald D Bartoe, is no longer available online from International Glass Review - but back issues can be ordered. This article also discusses issues related to tempered glass quality from the perspective of the roller manufacturer, and advocates good housekeeping and good fabricating practices. At one point, this article says, "Glass dust and debris deposited on the furnace rollers can be picked up by the glass." There are several color photos. International Glass Review is a tri-annual review of glass production and manufacturing, published by Contract Communications Limited a subsidiary of Euromoney Institutional Investor PLC, in London, England Articles in US Glass Magazine 4/98 Temper Temper Managing the Problems Inherent in Tempered Glass; By: Regina R. Johnson This 1998 US Glass Magazine article says in part that "particles such as glass fines from the cutting edging process and handling smudges that are not washed off the surface of glass before tempering will bake on to the surface, causing blemishes..... described throughout the industry by various names, including "orange peel," "heat prickling," "seeds," "bubbles," or just plain "garbage" that was not washed off prior to the glass entering the tempering furnace. During normal window cleaning after building construction, the pimples can be scraped off and the dragged across the glass surface, causing scratches" 6/99 Maximizing Ceramic Furnace Roll Performance By Renald D Bartoe, Frederick Caillaud, Dr. John Dodsworth and Jerry Osele The authors of this 1999 US Glass Magazine article identify glass fines and other surface deposits as defects. The article underlines the importance of plant cleanliness, roller & furnace cleanliness and maintenance, dust control, and states that "Effective use of the glass washer is critical to every tempering operation. The glass should be washed just prior to tempering... The glass washer must be operating properly with the detergents, brushes and rinse water at the manufacturer's recommended settings. Maintenance of the glass washer is equally important to ensure the glass is clean and without residue or debris that will be carried into the furnace... " Bulletins by GANA - (Glass Association of North America) Proper Procedures for Cleaning Architectural Glass Products Glass Association of North America This GANA bulletin is often interpreted as a "ban" on scrapers. GANA clearly does not condone or recommend scrapers, and scraping is not considered a "normal cleaning procedure" by GANA, This bulletin claims that "widespread" use of scrapers will "often" damage glass. Heat Treated Glass Surfaces are Different Glass Association of North America This GANA bulletin refers to the presence of fabricating debris as a "surface condition" - agrees that fabricating debris may be present on some tempered glass, and also states that scraping can result in damage, "if any microscopic particles have adhered to the surface". It does not, however, address the variable presence of fabricating debris. On most tempered glass, one side is fine, and the other side may or may not have fabricating debris. There is no explanation for why that occurs, or what is being done about it. The truth is that proper maintenance in the tempering plant yields a better tempered glass surface - but this GANA bulletin doesn't mention that. There is also the suggestion that ASTM standards allow the presence of fabricating debris, which suggests that builders have no choice but to accept tempered glass. However, the ASTM C 1036 standard contains disclaimers which seem to contradict that - and clearly, the ASTM standard does not actually state that detectable fabricating debris is acceptable. The conclusion suggests that "millions upon millions of square feet of glass have been installed with trouble free performance", the inference being that this is because this glass has been cleaned and maintained by professional window cleaners who didn't use scrapers. A window cleaner's view would probably be that most of those "millions upon millions of square feet of glass" have in fact felt a scraper - with no ill effect, because there was no fabricating debris problem. Scraper use among window cleaners is widespread - nearly universal. Window cleaning scrapers are offered by every major squeegee manufacturer, and sold by every major window cleaning supply house. General Information on Quality Tempered Glass What every window cleaner should know; By Daniel A Fields Information and facts regarding tempered glass in an outline format 6 second audio clip - recorded by Gary Mauer You can often detect fabricating debris on clean tempered glass by running a scraper lightly over the surface. Listen to MP3 file Listen to .WAV file (much larger file - slightly better quality) This recording will give you an indication of what to listen for. A microphone was attached to a scraper..... the scraper was placed on a piece of tempered glass, pushed a short way, then lifted and placed on a nearby piece of tempered glass which was loaded with fabricating debris and pushed again - lightly, so as not to scratch the glass. The smooth surface that you hear first would have been the top side when that particular piece of glass was tempered, and the rough surface you hear next was the bottom - the side that was touching rollers when that particular piece of glass passed through the tempering oven. The tinkling soun

How To Avoid Using A Razor Blade to Clean Glass

 

PILKINGTON Activ™ Self-Cleaning Glass

GLAZING GUIDELINES



Pilkington Activ™ Self-Cleaning Glass has a thin, clear, permanent, pyrolytic Titanium Oxide coating on one of its surfaces.  The coating has a hydrophilic property with makes raindrops spread out, or sheet, across the surface to wash away dirt particles. It also acts as a catalyst, when activated by daylight, to break down organic dirt into water vapor and CO2 gas. 
Pilkington Activ glass needs to be glazed with the coating on the #1 (outboard) surface. It should be located where it will can receive daylight because the coating utilizes the sun’s ultra violet light, either direct or diffuse indirect, to activate its self-cleaning action and destroy organic material on its surface.  There is sufficient indirect UV light to activate the coating, even on a north elevation (in the northern hemisphere), underneath overhanging roof eaves and behind an insect screen.
When glazed beside a light of clear, non-coated glass the Activ Glass will appear slightly brighter.


RECOMMENDED GLAZING GUIDELINES

Wet glazing tapes, such as “preshim” with a neoprene rod core enclosed in a high viscosity butyl, are designed to remain pliable and flexible over their design lifetime. These tapes may contain a significant percentage of oil that can migrate onto the glass surface.  This oil can sometimes be seen on the coated surface and can be difficult to remove without damaging the coating.
Silicone sealants can also exude silicone oil or plasticisers while they cure, and long afterwards.  These very thin layers of silicone oil are very difficult to remove from glass or coatings.  They are usually only visible when the glass is wet, and even then they are only noticeable by the different water droplet formation when compared to clean glass, but they do cover the coating and effectively inhibit the self-cleaning action.

ATS-169

2008/05/12
Page 2


Neoprene gaskets are often coated with extrusion oil or a lubrication liquid to assist installation.  This will usually be removed during the first glass cleaning, provided the lubricating liquid does not contain Silicone.
It is for these reasons that the following glazing materials are deemed compatible with Pilkington Activ Glass.
1.  Use a clean, oil-free, dry gasket system against the Pilkington Activ surface      Or
2.      Use silicone oil free, one or two component, curing, glazing sealants such as polysulfides and urethanes, Or
3.      SMX 505 by Soudal Inc. Contact: Mr Glen Kallgren, National Sales Manager. 682 553 1173.  gkallgren@soudal-inc.com 8888 Governors Row, Dallas, Texas 75247
Or 4.      Manusbond 35MP by Manus Products,
866 Industrial Blvd.
, West Waconia, MN 55387 . Contact: Mr. Brian Henjum, Dir. Sales, Tel 952 442 3323  brianh@manus.net Or
5.      Sonolastic 150 by Sonnerborn. Supplied by Chemrex, MN . 800 433 9517  (Avoid direct UV exposure)

Follow the manufacturers’ recommendations and insure that the sealants have adequate UV and weathering stability.


Identifying the Activ Coated Surface

The coated glass surface should be identified by the location of a lable on the non-coated glass side.  A special hand-held detector is available from EDTM, Toledo, Ohio , tel. 419 861 1030, www.edtm.com to positively identify the coated surface.
The fine scale roughness of the coating can be detected by added friction when it is rubbed with finger tips or finger nails.
Note: the coating emittance is the same as non-coated glass and so standard Low-E detectors cannot be used to identify the coated surface.

ATS-169

2008/05/12
Page 3


Maintenance and Cleaning Activ Glass

See ATS Bulletin #166 for details.  It is on the web at:
http://www.pilkington.com/the+americas/usa/english/building+products/ats+bulletins/default1.htm




The information contained in this bulletin is offered for assistance in the application of Pilkington North America Inc. flat glass products, but IT DOES NOT CONSTITUTE A WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE.  Actual performance may vary in particular applications.
[ Home Page | SimPole Brushes | New Products | COXREELS | Fiber Glass Poles | Testimonials | Ordering | Self Cleaning Glass Warning | How To Glass | DI Water | Pole Details | Product Survey | Contact Us | Newsletter | Water-Fed-Pole Links | Blog SimPole ]




nformational Bulletins
Proper Proced Paul is on the right tract because a lot of  new glass out there in not all bad but it does not like razor blades.
I manufacture the www.simpole.com which is made out of carbon fiber which is conductive to electric  wires.
If I warn the cleanlier to keep the pole away for wires that doesn’t make my product defective.
We need information or the type of glass and not  just say it is bad glass  because we can no longer use razor blades.
I see windows every day that have scratches on them from razor blades (not from us because we have stop using them and will WFP all new job first.)
There is other ways to clean window without razor blades.( WFP- PRESSURE WASHING)
If the manufacture does not want us to use them in why should we be so bull headed and tell we know better.
They make the glass and if  they say not to use razor blades on most new glass out there we should listen to them, It’s their Glass!
Ask  most of the follow window cleanlier and they will agree that in the last ten years the new type of glass will scratch even without FD problems.
Education is the key not always saying my way is best and I be dam if a let an manufacture  tell I can’t d razor blade!
We'Dew"Windows Inc
www.wedewwindows.com
"40 YEARS CLEANING WINDOWS"
SimPole Inc.
"WE USE WHAT WE SELL"
www.simpole.com

1-865-256-2225
ures for Cleaning Architectural Glass Products - GANA 01-0300 
     Download Bulletin in PDF Format (181 KB) Cleaning Glass Gana Web Site.
 http://www.scratched-glass.net/   Check out the site to avoid scrarching glass.
Click on titles to view articles -
the Acrobat Reader is required to view some articles.
  Please note:  All comments on this page were written by Gary Mauer.
No one should assume or infer that the owners of any other website endorse this website or any of the opinions expressed. Some of the links below lead directly to items on other websites. It is our policy to always provide equally prominent links to the home pages of these other websites. We urge all visitors to follow these document links and to read the entire document cited, and we also urge visitors to follow the home page links  in order to fully appreciate the content of the other website.
Click here to learn more about this website.
IWCA Seminar on Fabricating Debris Awareness - 2006
  Dan Fields, a highly regarded expert on the subject, presented a seminar called "Fabricating Debris Awareness" on Saturday, Feb. 18 at the 2006 IWCA Convention in Mesa, Arizona. Purchase 2006 IWCA Fabricating Debris Awareness CD online
Everyone with an interest in this issue needs to listen to this recording. This is a turning point in the dialog between window cleaners and glass companies. Double Audio CD.
IWCA Seminar on Glass Fabrication & Processes - 2005
  The day after a tour of the local Arch Aluminum & Glass tempering facility - during their 2005 convention in Orlando - the IWCA recorded a very interesting discussion about how hard these fabricators worked to produce better quality tempered glass for their customers.
During this discussion, these fabricators agreed that an ideal way to check for fabricating debris was to use a razor during regular QC checks on glass exiting tempering ovens.
Click here for Gary Mauer's article about the tour & seminar

Window cleaners were bussed to the Arch plant one day before the IWCA seminar. The editor of Glass Magazine - Nancy M. Davis - wrote an account of the discussion at the IWCA/Arch tour for the April 2005 issue. In that article, Max Perilstein, the Vice President of marketing for Arch, and leader of GANA’s Building Envelope Contractors division said, “We believe we're doing things the right way.” He advised window cleaners to “Investigate local glass fabricators. Ask if they’re doing the things we’re doing here.” That article was removed from the Glass Magazine website after only a few days.

Articles by Daniel A. Fields - WindowGuru@aol.com
Fields Construction Services, Inc.
5715 South Front Road, Building B-1
Livermore, CA 94550    - Phone: 925-294-8183
Scratched Glass Seminar
  Outline of Scratched Glass Seminar presented by Dan Fields at the Window Cleaning Network Picnic in Oconomowoc, Wisconsin, July 27, 2002.
This seminar covered the leading cause of glass scratching - defective tempered glass surfaces. "Scrapers don't scratch glass - fabricating debris does."
Construction Window CleaningA Primer; By Daniel A Fields
   The purpose of this article is to help enlighten general contractors, window cleaners, and other responsible parties in the residential construction industry on how to identify some of the numerous causes of scratched glass.  This article discusses the responsibilities of the construction window cleaner, other subcontractors and the general contractor, the major causes of scratched glass, and the possible solutions to this widespread problem.
 
Glass Quality
By Daniel A Fields
   An illustrated essay on tempered glass quality - the origins of fabricating debris, and what needs to be done about it.
Article by Gary Mauer 
Scrapers & Fabricating Debris Issues - Revised 2/23/04
  Window cleaners: This article will help you and your customers understand the problems presented by fabricating debris on some heat treated glass, and why you need to have a fabricating debris damage liability waiver signed before you scrape tempered glass. This update contains several clarifications, including the statement that "The incidence of fabricating debris is greatly minimized when temperers adhere to all recommended maintenance procedures for washers, rollers and other tempering equipment."
Print copies and show it to builders. Help them realize why they should insist on quality tempered glass - that can be scraped - and why they need to sign your waiver.
Builders are encouraged to manage fabricating debris as a manufacturing defect on some of the tempered glass they are getting, and address this issue with their suppliers. Work with them to assure that the uncoated tempered glass you're getting can be successfully cleaned with a properly used scraper. If you can do that, you'll have no more problems with tempered glass damage than you do with annealed.
This article may be reprinted and redistributed by anyone who wishes to. Photocopying and fax distribution is discouraged - but only because color photos of glass defects are involved.
I recommend printing from the original PDF file, or emailing the file itself to interested parties.
Article in the International Glass Review
Partnering with the Glass Fabricating Industry
  This 2002 International Glass Review  article by the leading supplier of furnace rollers points out they offer "free seminars to customers focusing on roller properties, cleaning and maintenance procedures, roller refurbishing and regrinding options and precautions, the effects of the plant environment and fabricating practices on tempered glass." They also offer laboratory analysis as a free service to their clients, to properly identify "glass surface conditions or markings".
At one point, this article says, "Most often the conditions that appear on glass surfaces during the heat treating process are related to foreign materials that have been mechanically impinged into the glass or that has damage the glass as it passes over the rollers. "
An illustrated article from the 2001 International Glass Review entitled,
The dynamics of ceramic rollers
Operating and maintenance practices to produce quality tempered glass; By Renald D Bartoe, is no longer available online from International Glass Review - but back issues can be ordered.
This article also discusses issues related to tempered glass quality from the perspective of the roller manufacturer, and  advocates good housekeeping and good fabricating practices. At one point, this article says, "Glass dust and debris deposited on the furnace rollers can be picked up by the glass." There are several color photos.
International Glass Review is a tri-annual review of glass production and manufacturing, published by Contract Communications Limited a subsidiary of Euromoney Institutional Investor PLC, in London, England
Articles in US Glass Magazine
 4/98 Temper TemperManaging the Problems Inherent in Tempered Glass; By: Regina R. Johnson
  This 1998 US Glass Magazine article says in part that "particles such as glass fines from the cutting edging process and handling smudges that are not washed off the surface of glass before tempering will bake on to the surface, causing blemishes..... described throughout the industry by various names, including "orange peel," "heat prickling," "seeds," "bubbles," or just plain "garbage" that was not washed off prior to the glass entering the tempering furnace.  During normal window cleaning after building construction, the pimples can be scraped off and the dragged across the glass surface, causing scratches"

6/99 Maximizing Ceramic Furnace Roll Performance
By Renald D Bartoe, Frederick Caillaud, Dr. John Dodsworth and Jerry Osele
  The authors of this 1999 US Glass Magazine article identify glass fines and other surface deposits as defects. The article underlines the importance of plant cleanliness, roller & furnace cleanliness and maintenance, dust control, and states that "Effective use of the glass washer is critical to every tempering operation.  The glass should be washed just prior to tempering... The glass washer must be operating properly with the detergents, brushes and rinse water at the manufacturer's recommended settings.  Maintenance of the glass washer is equally important to ensure the glass is clean and without residue or debris that will be carried into the furnace... "
Bulletins by GANA - (Glass Association of North America)
Proper Procedures for Cleaning Architectural Glass Products
Glass Association of North America
  This GANA bulletin is often interpreted as a  "ban" on scrapers. GANA clearly does not condone or recommend scrapers, and scraping is not considered a "normal cleaning procedure" by GANA,  This bulletin  claims that "widespread" use of scrapers will "often" damage glass. 
Heat Treated Glass Surfaces are Different
Glass Association of North America
  This GANA bulletin refers to the presence of fabricating debris as a "surface condition"  - agrees that fabricating debris may be present on some tempered glass, and also states that scraping can result in damage, "if any microscopic particles have adhered to the surface". It does not, however, address the variable presence of fabricating debris. On most tempered glass, one side is fine, and the other side may or may not have fabricating debris. There is no explanation for why that occurs, or what is being done about it.
The truth is that proper maintenance in the tempering plant yields a better tempered glass surface - but this GANA bulletin doesn't mention that.
There is also the suggestion that ASTM standards allow the presence of fabricating debris, which suggests that builders have no choice but to accept tempered glass. However, the ASTM C 1036 standard contains disclaimers which seem to contradict that - and clearly, the ASTM standard does not actually state that detectable fabricating debris is acceptable.

The conclusion suggests that "millions upon millions of square feet of glass have been installed with trouble free performance", the inference being that this is because this glass has been cleaned and maintained by professional window cleaners who didn't use scrapers.
A window cleaner's view would probably be that most of those "millions upon millions of square feet of glass" have in fact felt a scraper - with no ill effect, because there was no fabricating debris problem. Scraper use among window cleaners is widespread - nearly universal. Window cleaning scrapers are offered by every major squeegee manufacturer, and sold by every major window cleaning supply house.
General Information on Quality Tempered GlassWhat every window cleaner should know; By Daniel A Fields
   Information and facts regarding tempered glass in an outline format  
6 second audio clip - recorded by Gary Mauer 
You can often detect fabricating debris on clean tempered glass by running a scraper lightly over the surface.  Listen to MP3 file      
Listen to .WAV file (much larger file - slightly better quality)

This recording will give you an indication of what to listen for.
A microphone was attached to a scraper..... the scraper was placed on a piece of tempered glass, pushed a short way, then lifted and placed on a nearby piece of tempered glass which was loaded with fabricating debris and pushed again - lightly, so as not to scratch the glass. 
The smooth surface that you hear first would have been the top side when that particular piece of glass was tempered, and the rough surface you hear next was the bottom - the side that was touching rollers when that particular piece of glass passed through the tempering oven.
The tinkling sound you hear is little glass fines and other fabricating debris. This is the "tinkle test"....   If you've never heard this before, you'll be impressed - or maybe you'll think we faked it. 

If you hear this sound, you cannot apply pressure with a scraper, because if you do, some of this fabricating debris will become trapped under the scraper and scratch the glass. 
Caution -  Fabricating debris is variable, and this is a more extreme example. It won't always sound this bad, and you cannot count on feeling or hearing this surface defect while you are working - particularly on a messy construction site.

Miscellaneous Links
Mohs Hardness scale at About.comThis and other Mohs hardness scale web pages rank glass and blades at about the same hardness. Unfortunately, most Mohs hardness scale web pages are written by and for gemologists. Those which do mention glass and blades are similar in hardness tend to mention the fact only in passi