There’s More Behind Your Windshield Than You Think.
The science, the standards, and the truth behind a professional windshield installation.
LOCAL AUTO GLASS / WINDSHIELD INSTALLATION GUIDE
How Local Auto Glass repairs, replaces and bonds windshields
A windshield replacement starts with the right glass, a sound surface to bond it to, and an adhesive system that suits the vehicle and the conditions. Our owner is a master auto glass technician with Sika adhesive-system certification. Our technicians are trained to assess damage, prepare the glass and vehicle, and explain the product choice, release time and aftercare for your job.
Can a new windshield get wet?
During installation, the bonding surfaces must stay dry. We need clean, dry contact surfaces where the urethane will bond to the glass and vehicle. Rain, pooled water, condensation or frost on those surfaces can interfere with adhesion. If rain is falling at a mobile appointment, we need a sheltered work area that keeps the glass and vehicle opening dry throughout the installation. If we can’t maintain those conditions, we’ll arrange another location or time. Sika vehicle glass replacement guidance
After installation and release, ordinary rain on the outside of the glass is generally fine. Rain on the face of a properly installed windshield is different from water on a surface where we’re trying to make a fresh bond. If it starts raining during your drive-away hold, leave the vehicle parked where your technician directs until your release time. State Auto Glass aftercare FAQ · AGSC drive-away guidance
Wait 24 hours after replacement before using an automatic car wash. That includes touchless washes. Pressurized jets and brushes can put force on the seal and surrounding trim while the adhesive continues to cure. Ask us about direct pressure washing around the glass, and follow any instructions we give you for your vehicle or retention tape. Liberty Auto Glass aftercare guidance
What happens during a chip repair?
A repair keeps the original windshield in place. We inspect the damage from both sides and check its size, depth and location. Damage in the driver’s main viewing area, near a camera’s view, through the inner layer, or affected by contamination may call for replacement. The type of break and the vehicle manufacturer’s instructions also matter. Laminated glass repair standard, sections 6–8
For a repairable chip, we prepare the damaged area, remove or displace trapped air, and fill the break with a clear resin. The resin is cured as directed by the repair system, typically with a UV light. We finish the surface flush and inspect the repair from the driver’s position. A faint mark can remain. The goal is to stabilize the damage and improve clarity where possible. A chip repair has its own resin curing procedure. The urethane drive-away chart applies to a bonded replacement. Repair standard, sections 8–11 · Delta Kits resin repair demonstration
Windshield replacement, steps 1–3
1. Identify the right glass. We check the vehicle and its equipment before removing the original windshield. The correct part may need a specific camera bracket, rain sensor mount, heating element or head-up display compatibility. We check the vehicle manufacturer’s service information for the applicable glass, installation and calibration procedures.
2. Check the work area and materials. For mobile work, we look at shelter, weather, and the temperatures of the air, bonding surfaces and adhesive. We also check the product’s storage requirements and expiration date. These checks help determine which system can be used that day.
3. Remove the damaged glass and inspect the opening. We protect the surrounding surfaces and remove the necessary trim and equipment. With the glass out, we can see the pinchweld, the metal flange around the opening. Rust, damaged paint, prior sealants and poor previous work can affect the new bond. If the opening needs body repair before we can make a sound installation, we explain what we found and pause the job. Sika replacement guideline · AGSC replacement standard, sections 4–8
Windshield replacement, steps 4–6
4. Prepare both sides of the bond. We trim sound existing urethane where the procedure calls for it, address scratches or exposed metal as directed, and clean the bonding area on the replacement glass. The glass, its black ceramic border, the existing urethane and the vehicle’s painted flange can each have different preparation requirements.
5. Apply the urethane and set the glass. We apply a continuous bead shaped and sized for the installation. The glass has to be aligned and seated within the adhesive’s working time, while the bead can still make proper contact with both surfaces. We reinstall the applicable trim, wipers and sensors and check their operation.
6. Handle calibration and release. If the vehicle requires camera calibration, we follow the vehicle-specific procedure and explain the calibration plan and status. A road-based calibration begins after the adhesive’s minimum drive-away time. At handoff, we tell you when the vehicle can move and which aftercare instructions apply. Sika replacement guideline · AGSC replacement standard, sections 4–8
The three Sika urethanes compared
For our bonded windshield replacements, Local Auto Glass uses SikaTack® ULTIMATE and SikaTack® ASAP+. We choose the system that fits the vehicle and work conditions. SikaTack® MACH-30 XV is included for comparison.
ULTIMATE · 30-minute published minimum drive-away time for cars under Sika’s charted conditions. Cold-applied. The adhesive itself must be 50–120°F. It can bond to properly cleaned glass and ceramic frit without an added glass primer or activator. Vehicle-side preparation still depends on the surface. ULTIMATE product data sheet
ASAP+ · 30-minute published minimum drive-away time for cars under Sika’s charted conditions. Hot-applied. The adhesive is conditioned to 167–194°F in a Sika-approved oven for at least one hour before use. The glass receives the specified Sika pretreatment. ASAP+ product data sheet
MACH-30 XV · 30 minutes in most charted conditions for cars and 45 minutes in some warm, dry conditions. At 75°F and 30% relative humidity, Sika’s chart shows 45 minutes. This is a cold-applied adhesive with a product temperature range of 50–120°F. The glass receives the specified Sika pretreatment. The high-viscosity formula helps the bead hold its shape. MACH-30 XV product data sheet
The data sheets list application temperatures on page 1 and the drive-away charts on page 2. Your technician will give you the release time for your vehicle.
Air, glass and adhesive temperatures
Ambient means the air around the job. Substrate means the surface the urethane will touch, such as the glass or the prepared vehicle opening. Product temperature means the temperature of the urethane itself. A windshield sitting in the sun or a vehicle parked outside overnight can have a surface temperature quite different from the air. Sika’s U.S. sheets list 0–120°F for ambient air and 0–170°F for bonding surfaces for these three products. The adhesive and any required preparation products have their own limits. ULTIMATE · ASAP+ · MACH-30 XV
At Local Auto Glass, 40°F is our outdoor cutoff for ULTIMATE. Below that, we assess whether ASAP+ is suitable. Sika’s training manual provides cold-weather procedures for ASAP+ down to its listed 0°F application limit. We still need dry, frost-free surfaces and the right conditions for every step. Cold can also change the prep time. For example, Sika calls for more drying time for Aktivator PRO at the colder end of its range. If we can’t meet the system’s conditions outdoors, we need a suitable sheltered location or a different appointment time. Sika U.S. technician training manual, section 7
Cleaners, activators, primers and urethane
A compatible glass cleaner removes contamination from the bond area. An activator promotes adhesion on the surfaces specified by the system. A primer prepares certain surfaces and can be part of the specified treatment for exposed metal. The urethane is the adhesive that holds the glass to the vehicle.
We choose and apply these products as a system and allow the required drying time before bonding. With a primerless-to-glass product such as ULTIMATE, careful cleaning and correct vehicle-side preparation still matter. Sika vehicle glass replacement guidance on surface preparation
What the crash testing tells you
A bonded windshield helps keep occupants inside the vehicle in a crash and can support passenger airbag deployment on some vehicles. Federal Motor Vehicle Safety Standard 212 sets windshield-retention requirements in a crash test for covered vehicles. Sika uses that standard to validate the drive-away times it publishes for these adhesives. Federal windshield mounting standard · Sika U.S. technician training manual
The Auto Glass Safety Council’s replacement standard calls for a vehicle-manufacturer-approved retention system or one the retention-system manufacturer certifies in writing as equivalent. It also calls for following the system manufacturer’s current written instructions, including storage, weather procedures and drive-away timing. We check the vehicle requirements and follow the current vehicle and adhesive manufacturer instructions for the installation. AGSC replacement standard, sections 5 and 6
Working time, drive-away time and full cure
Working time is the installer’s window to set the glass after applying urethane. At Sika’s reference conditions of 73°F and 50% relative humidity, typical working times are 8 minutes for ULTIMATE, 7 minutes for ASAP+, and 8 minutes for MACH-30 XV. Conditions can shorten that window. ULTIMATE · ASAP+ · MACH-30 XV
Minimum drive-away time is how long the vehicle must stay parked after installation for the bond to reach the tested strength needed for release. Your technician checks the applicable chart and tells you the release time for your vehicle. Installation and any required calibration also factor into the time you should plan for the appointment. AGSC drive-away guidance
Full cure is when the adhesive has cured through the entire bead. These one-part urethanes react with moisture in the air and cure from the outside inward. The center can continue curing for days after the bond reaches drive-away strength. That’s why we give you a release time for driving and separate instructions for washing and caring for the new glass. Sika U.S. technician training manual, section 6.7
Before you take the keys
Confirm your release time, when any tape can come off, and the status of any required camera calibration. If you notice a water leak, new wind noise, loose trim or a driver-assistance warning after service, call us so we can inspect it. If visibility or safe operation is affected, keep the vehicle parked and call for guidance. Windshield Aftercare · ADAS Calibration Guide
Have a question about the urethane we’ll use on your vehicle or whether we can complete your mobile appointment in the weather? Call Local Auto Glass at 617-959-1884 or send us a text. For a repair or replacement quote in Quincy or the surrounding area, send your VIN, a close-up and a wider photo of the damage, and your service location. Request a quote
Sources you can check
Sika technical references ULTIMATE data sheet · ASAP+ data sheet · MACH-30 XV data sheet · Technician training manual
Industry standards and customer guidance AGSC windshield replacement standard · Laminated glass repair standard · AGSC minimum drive-away times · Federal windshield retention test
Questions about your windshield? Call or text Local Auto Glass.
Local Auto Glass LLC | 133 S. Walnut St., Quincy, MA 02169 | localautoglass@outlook.com