by Bob Beranek

Is the old cold knife disappearing? Will the wire/cord crimping tool overtake other auto glass removal tools? Are violent power removal tools going to be replaced with more passive tools?

Recently I thought about who invented the cold knife and when it was first offered? It certainly had a good run. When I started in the industry, in the mid-70s, the cold knife was a major tool in my toolbox along with a hook tool and a utility knife. Wire and handles were also present, but the cold knife took the lead when it came to glued-in glass removal tools.

I figured the cold knife would be easy to research, so I began probing. There was no shortage of sites offering “auto glass removal tools” for sale, but the history of the tool was seriously lacking. The many names associated to the tool over the years caused a major problem. Cold knife, cable knife, windshield removal tool were all used interchangeably, which makes it difficult to track down.

The first cold knife

I called my friend and colleague, Bob Nilsson from Ultra Wiz who steered me to Jeff Cothery. Jeff told me that his father, Harry R Cothery, invented the cold knife based on PPG’s suggestion in the early 1960’s. He went on to invent and patent the “Hot Knife” as well, patent number 3,448,517. Unfortunately the hot knife never really took off like the cold knife did, and due to the existence of similar tools, it was unable to be patented. Jeff turned out to be a wealth of information and I want to thank him for satisfying my curiosity.

The first hot knife

Now to address the questions above.

Is the cold knife disappearing? I believe current technicians will never let it disappear completely. The cold knife took them a while to master and once they did there was never a tool that could remove the glass faster and smoother than a well sharpened cold knife.

Will the wire/cord crimping tool overcome other auto glass removal tools? With the potential for vehicle damage minimized, no physical exertion required, and providing even an inexperienced tech the ability for a safe efficient removal, they provide a lot of benefits. As people get used to seeing wire-out tools and trying them, they will increase in popularity.

Will the power removal tools be replaced with more passive removal tools? I don’t think so. Power tools are the fix when all else fails. If power tools are used incorrectly they can cause serious damage to the vehicle, but for experience techs there will always be a place in the tool box for the ultimate tool that will “get-er done”.

You have to say a few things about Harry’s cold knife invention, the long learning curve it takes to master and the effort expended using it, the cold knife, when used properly still works great. Don’t throw your cold knife away yet.

The fall season is here, and there are a few things you may need to adjust to compensate for the colder weather.

  • Clothing – Colder weather means proper clothing should be acquired for comfort and quality installations. A cold technician hurries through their installations and can cut corners. You should dress in layers, so when the day wears on and temperatures rise a layer of clothing can come off.

    Photo courtesy of

    Photo courtesy of

  • Scheduling – It’s great to do installations in the open air during the summer and spring. However, the cold winds of the fall and winter are not as pleasant. Make sure to schedule jobs with shelter available as often as possible because cold winds and wet weather are not conducive to proper installations.
  • Tools – You might be able to get by with dull blades and cold knives in the summertime but fall brings stiffer and harder to cut urethane beads. Make sure your blades are sharpened in the morning and honed up during the day and that your power tools are in good working order.
  • Parts – Cooler weather brings more brittle plastic parts. Make sure your parts box is stocked and inventoried. Also you should have your heat gun and hair dryer at the ready to warm up vinyl and dry out pinchwelds. The sun is not as warm in the fall so be prepared to smooth out that “washboard” moulding before you leave each job.
  • Adhesives – Sealants and adhesives will be stiffer in colder temps. Keep them warm by taking them in the shop at night. During the day you can keep them warm by exposing them to warmer air blowing from the floor heaters. I do not recommend using your defrosters on the dashboard, as that can make those cartridges or packages flying projectiles in case of an accident. Check with your adhesive manufacturers’ instructions so you will know what you can and cannot do when storing your chemicals.
  • Primers – Most primers have a longer drying time in colder weather. Make sure you check the proper timing and adjust your installation procedures to compensate.
  • ADAS – Many Advanced Driver Assist Systems (ADAS) turn themselves off when the cameras and sensors cannot see the road markings due to rain or snow. You should be aware of this and make sure your customer knows recalibration is required even though the system has shut itself down.
  • MDAT – The Minimum Drive Away Times (MDAT) may have to be adjusted to compensate for cooler and dryer temperature. Some adhesive systems do not need any adjustments except for some primer dry times, however others do need to be adjusted according to the heat and humidity of the day. Keep you MDAT charts available for reference.

There have been discussions about carmakers requiring pre & post scans when doing any repair work on their vehicles lately. “Scanning” means using a tool to read the vehicle’s On-Board Diagnostic (OBDII) computer.

The scan taps into the OBDII port under the driver side dashboard and flags “fault” codes that are tripped by things that cause problems for the vehicle. Dealerships, body shops and other repair facilities are already required to perform a pre-scan prior to beginning any repair procedure to make sure there are no undetermined issues to deal with, along with and a post-scan after the repair is complete to confirm the repair.

Photo courtesy of

Photo courtesy of

Vehicle technology built into the modern vehicle is categorized under two headings, safety related or performance related. Safety related technology is the most important. If safety related features are not performing properly, the repair facility is obligated to fix the problem. An example might be the Advanced Driver Assist Systems (ADAS). I say “might be” because it is still unclear if ADAS is an “assist” system or a “safety” system.

Some safety systems are noticeable to the driver via lights, sounds, and warnings that pop up on the dash or fill the cab with audible warnings. Others are intertwined with other systems that are read by the scan of the vehicle and are not obvious to the driver. The carmaker wants to make sure the vehicle owner has the most current safety technology up and working correctly.  Directing and requiring scans help assure the safety of occupants in the vehicle.

The other scanning requirement is of performance related technology. Vehicle owners spend thousands of dollars to have the latest in performance features and expect them to be in working order. When an owner enters a repair facility, they expect their vehicle to be in the same working order as when it arrived at the repair shop. Pre & post scans assure the customer of that expectation.

What does this have to do with auto glass? Our challenge is to step up. This new technology has reached our industry through our connection to ADAS and with other glass related systems. We must rise to the level of professionalism of our sister industries.

More and more auto repairers pinpoint systems that are not operating properly through a pre-scan process. They then deliver that vehicle back to the owners, with all of the systems repaired and operating at peak performance and safety; which are documented through the post-scan process.  Our industry cannot be any less of a service provider.

There are dozens of scanners available to the professional and consumer and can range from under $100 to thousands. Each scanner offers different levels of performance from superficial readings for the car owner to global scans that professionals use to diagnosis complex systems.

My advice – do your homework and determine the scanner that will fit the needs of your shop. Purchase and use it on every vehicle. When an issue shows itself, determine if you have the ability and equipment to repair the problem. If not, inform the customer of the issue and suggest a repair by a professional that can complete it.