by Bob Beranek
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What is a flap?” A flap is a sliver of cured urethane lying on top of another piece of cured urethane, which can cause a leak or bonding problems. Any time you are replacing a windshield and stripping back the existing bead, flaps in the urethane must be eliminated.

A flap can be caused by the cut-out procedure, strip-out procedure or by a combination of the two.

A flap can be caused by the cut-out procedure, strip-out procedure or by a combination of the two. Often, a flap is not noticed by the technician due to insufficient light, compressed timelines or the (proper) practice of not touching the bead after the strip-out procedure.

We never want to create a flap, but it can be easy to do. For example, using a cut-out tool in one direction and then finishing the cut-out action in the opposite direction can cause a flap where the start and stop points overlap. Most of the time, this flap is eliminated by the strip-out action of the full strip process, but if the flap is deep enough it can go unnoticed. The sliver left behind is almost invisible to the technician and easily missed.

If the flap is deep enough it can go unnoticed.

A flap can also be caused at the start and end point of the strip-out procedure, where the technician trims back the existing urethane bead. Again, a flap can be created if the tech strips the urethane in one direction and then finishes in the opposite direction.

If a flap is not discovered and eliminated, the new fresh bead of urethane is applied right over it, which can cause an entry way for water into the vehicle. The flap also creates a bond problem.

The first step in eliminating flaps is to realize they exist, and to look for them. Use your strip-out tool to find possible flaps within your trimmed-back bead. Gently run the tool over suspected areas, and try to catch the blade on the loose flaps. Once found, cut them off.

Try to catch the blade on the loose flaps.

I know it’s easier to use your gloved hand to find the flaps, but you run the risk of contaminating the freshly exposed existing bead with your gloves. If you must use your hand to find and eliminate a flap, make sure you wipe the surface clean according to your adhesive manufacturer’s instructions.

The flap leak can be difficult to fix. With other leaks, a little bead of fresh urethane placed over the leak area will work. However, with a “flap leak” this technique may only shift the water leak to another location. The best way to fix the leak is to remove and install the windshield. However, if you decide not to do a full removal and installation, I suggest the repair bead be extended the entire length of the roofline and down the sides an inch or two. This will divert the water and have a better chance of sealing it for good.

You run the risk of contaminating the freshly exposed existing bead with your gloves.

Don’t forget, the best thing to do is not have flaps in the first place. Take the time to look and eliminate them.

I hope everyone is having a happy and profitable 2017.  Last year was an eventful (and sometimes frustrating) year for the AGR Industry, and I predict 2017 will not be any different. New dealer directives on glass and part usage and the expectation of new calibration tool introductions will prove to be exciting and challenging.  Keep visiting this site for updates as they happen.

Today, however, I want to address a problem that can be solved with chemistry and a little extra effort. With the increase in underside mouldings, lower cowl retaining devices and self-adhesive clips, we all have faced the challenge of getting these products to adhere aggressively to plastic and painted surfaces. To put it bluntly, many of these products just don’t stick the way they should.

In the case of self-adhesive moulding clips, technicians have attempted to fix the problem with the use of “liquid clips” and a length of tape to hold the moulding down until the urethane cures. This is not the way mouldings should be reinstalled. For consistent performance, clips should be properly adhered, and the moulding attached to the clips by design.

Proper cleaning and preparation of surfaces is the key to making added parts stick during an installation. I instruct the use of self-adhesive parts this way:

  • Clean both surfaces of any residue;
  • Warm the adhesive tape to body temperature; and
  • Press in the part place for five or more seconds to allow the adhesive to bond.

The Material being prepped for application

This process works consistently if you make the effort to follow the process. However, if any of the three steps above are not followed, the result is adhesive failure – with the mouldings, cowl or clips coming loose and flying away at highway speeds.

However, I’ve recently learned about other products that can help “add on” parts stick to surfaces. At an auto dealership training course I gave last month, the body shop manager showed me a product meant to be used with double-faced tape. The generic name is an adhesion promoter.

The foam applique being applied.

I was amazed at the difference this product can make. Adhesion promoters are used routinely in body shops, but I believe they are very practical in the AGR industry, too. The directions are simple;  apply the promoter to the cleaned surface (or surfaces) that will be attached by the adhesive tape, allow it to dry 60-90 seconds, and then press into place. Once you use it the first time, you may never want to be without it again.

There are a number of brands of adhesion promoter out there, so do your own experimenting. Some products are in bottles, some are in individually wrapped packages, some have applicators and some are in saturated sponges for ease of use. Contact me at if you have experience or suggestions for using them.

Modern day wire-out tools are becoming more necessary with every new vehicle introduction.

Government standards now mandate an average fuel economy of 54.5 miles per gallon for the 2025 model year, according to the New York Times. To meet that new standard, glass must be thinner and be as flush to the body as possible to reduce weight and drag.

The close tolerances demand different or better cut-out tools to reduce damage to the paint and remove the glass without breaking it.

This is part of the reason why a number of wire-out tools are being introduced to the market. Each tool has its pros and cons, and each does a very good job of removing glass without damage.

However, the biggest complaint about wire tools is the time it takes to set up and operate the tool. Time is frequently the deciding factor when purchasing a tool. Even the best wire-out professionals acknowledge that the process takes longer than other methods. The trade-off, they argue, is the reduction in damage is worth the extra time.

That may be true, but when a small business needs to pay its people and keep a business running in a competitive market, being productive with time is a key component.

I believe that you can do both – be productive and provide a quality glass removal without damage. It takes skill, practice and knowledge of what to look for (and at) to facilitate the fastest removal with wire.  What should you consider?

  • Is the glass original equipment (OE)? If it is, and if it does not have gravity stops at the bottom, then you will have to separate the guide pins at the top edge of the glass before proceeding with the removal. This is done by using a flexible sharpened putty knife or paddle tool blade to separate the pins from the glass surface. Otherwise, the pins can cause the wire or cord to break, thus prolonging the removal. If the glass is not OE, you may want to use wire instead of cord to make the removal easier. A previous installer may have used larger and thicker beads than the OE installer and the wire will cut through them better than the cord.
  • Cord or wire? That is entirely up to the technician. The wire cuts the urethane, and the cord is pulled through it. Cord is reusable if used correctly, but wire is a consumable discarded after every use. Cord is usually more expensive than wire, but due to its reuse capability, that may come out as the same cost.
  • The smaller the angle, the easier the tool works. The lower the degree of angle (under 90 degrees), the easier the cut and the less likely the wire will break during removal. A good angle is 45 degrees; 30 degrees is better and 15 is better yet. When the wire gets to 90 degrees of the tool’s spindle, move the tool closer to a corner edge and continue the cut.
  • Keep the wire as close to the inside glass surface as possible. This will aid in the ease of the cut and prevent possible damage to the interior garnish moulding. To achieve this, use the protective pad included in the kit or use a plastic stick to force the wire to the interior surface – or develop your own method.
  • Clean the interior surface of the glass and wipe down the vacuum cup for best suction to the glass. There is a great deal of tension on the wire, cord and cup. If the glass is dirty or the cup is wet or soiled, the cup will not hold suction and it can “walk” on you. Clean all surfaces before you begin glass removal.
  • Some tools work best when the distance between the spindle and the bead is less than three feet. Anything longer will put more tension on the wire or cord and cause it to break prematurely.
  • If you have a manual wire tool rather than a power tool, it may be easier to feel when the wire is at a breaking point. If you feel that the wire is tensing up, make short pulls and then allow the wire to rest. Then repeat as often as necessary until you feel the wire pull easier. This usually occurs around the corners and at the end of the cutout.
  • If you have a power tool, listen to the drain on the power tool as a hint of wire tension. If the tool sounds like it is struggling to pull the wire, inspect it to determine the cause of the obstruction. It could be a burr in the metal under the glass or the wire could be under the metal of the lower pinchweld. If so, relax the wire and get it between the glass and the adhesive.
  • Be extremely careful around the VIN plate – the wire can cut off the VIN plate easily. You DO NOT want to cut off the VIN plate. This has happened to me, and it is a major problem that involves the vehicle manufacturer, the state government and the owner. Make sure your wire is above the plate when it gets to that area of the urethane bead.

Each wire-out tool has its own little hints and tricks for efficient use. I urge you to listen to the manufacturer, learn and use those tricks. They are well worth the effort and training. Good luck.