How to Repair a Windshield Crack or Chip Yourself

What a DIY resin kit can and cannot fix

A DIY resin kit can fill a short crack or a small chip in the outer layer of a laminated windshield. It cannot fix damage on the inner layer, damage through both layers or a crack longer than the kit’s rated length. Each kit maker sets its own size limits, and a kit sold for chips may not be meant for cracks. The table compares the makers’ limits with shop policy and the repair standard.

Rain-X says its kit removes the air from the break and fills it with resin, which is also how ROLAGS defines a repair. Whether a kit’s result is good enough is covered in do windshield repair kits really work. To pick a kit for your type of damage, see how to compare windshield chip repair kits by type.

Size and location limits under ROLAGS

ROLAGS 002-2022, the US Repair of Laminated Automotive Glass Standard, allows a single crack of up to 14 inches (350 mm) to be repaired. The standard is written for trained technicians. Its other limits are 1 inch (25 mm) for a bullseye, 2 inches (50 mm) for the body of a combination break and 3 inches (75 mm) for a star break. A shorter kit limit still applies to a DIY repair.

Location matters as much as size. ROLAGS defines a driver’s primary viewing area 12 inches (300 mm) wide, centered on the driver and running the height of the wiper sweep. Inside that band, the standard calls for replacement in three cases:

• The damage is larger than 1 inch (25 mm) across.
• The finished pit would be larger than 3/16 inch (5 mm).
• The repair would sit within 4 inches (100 mm) of another repair.

The band runs 6 inches to each side of the steering wheel’s center. Full limits and measuring tips are in how big a windshield crack can be repaired.

Before you start: stop the spread, clean and dry the crack

The break has to be clean and dry before any resin goes in. Rain-X says to repair the damage as soon as possible, before dirt or water gets into the break. ROLAGS lists trapped dirt that cannot be cleaned out as a reason to replace the windshield. The kit makers’ directions give this prep:

• Park in shade. Rain-X says to keep the windshield out of direct sunlight until the repair is done.
• Check that the glass is within your kit’s temperature range, shown in the curing table below.
• Wipe dust and dirt off the damage. Rain-X says to use a dry paper towel.
• Lift loose glass out of the impact point with the kit’s push pin or razor blade.
• Keep resin away from the paint. Permatex warns that its resin can damage the car’s finish.

Do not lean on the glass. Rain-X warns that excessive pressure will extend the crack. A crack can also grow past a kit’s limit while you wait for a dry, mild day. Short-term steps are in how to stop a windshield crack from spreading.

How to repair a windshield crack with a resin kit

These steps follow the crack directions on the Rain-X 600001 instruction sheet. Your own kit’s sheet overrides them if it differs.

Chips, bullseyes and stars use a bridge or pedestal over the impact point instead of open dispensing. In the Permatex kit, an adhesive seal and a pedestal hold a syringe over the pit. The syringe holds a vacuum for 10 minutes, then pushes resin in under pressure for at least 20 minutes. A drop of resin and a curing strip then seal the pit. The Rain-X chip method uses a screw-in pressure driver and lets the resin soak in for 4 to 6 minutes. Rain-X says the suction cups must not cover any crack that runs out from the impact point.

Curing the resin: sunlight, UV light, heat, cold and rain

Kit resin hardens under ultraviolet light, so the car goes into the sun only after the filling is done. Rain-X says proper curing needs strong, direct UV light and that natural sunlight is ideal. Without sunlight, Rain-X says a UV light with an output of 315 to 405 nanometers is required. Permatex says its resin cures in 15 minutes of direct sunlight, or in at least 1 hour outside on a hazy day. The two makers set different temperature and timing rules:

Rain and wet glass work against the repair. Rain-X tells users to repair before water contaminates the break and to wipe the glass dry first. If it is raining, wait until the glass and the break are dry and work under cover. Rain-X warns that excessive heat may cause further damage, so use a hair dryer with care.

Why the repair still shows, and how to check it

A resin repair reduces how much a crack shows, and it usually leaves a small mark. ROLAGS calls this remnant a cosmetic blemish. The cured resin is meant to come close to the refractive index of the glass, so it scatters less light than the open crack. Rain-X says unrepaired areas show as dark green or black spots. Permatex notes that its repair may not completely remove the blemish or permanently fill the pit. Safelite tells customers that a slight blemish is normal.

Rain-X gives two causes of poor results. Resin applied too quickly leaves air pockets, and a contaminated crack does not fill well. Its own test for success is that the crack “vanishes” when viewed at a 45-degree angle. Check both sides of the glass at that angle. Rain-X generally does not recommend a second kit on the same damage. For more checks, see how to know if a windshield repair worked. To remove leftover resin film and haze, read how to clean a windshield after resin repair.

When the windshield needs a professional or replacement

Call a glass shop when the damage is outside your kit’s limits or when ROLAGS calls for replacement:

• The damage is on the inner layer or goes through both layers.
• Three or more long cracks spread from one impact point.
• The plastic interlayer is damaged or discolored, or the pit is larger than 3/8 inch (9 mm).
• The crack reaches more than one edge, or it is a stress crack with no impact point.

Safelite says damage in the forward camera’s line of sight usually means replacement. A crack beyond your kit’s limit but within 14 inches may suit a shop that does long-crack repair. AAA puts a shop crack repair at $100 to $150, and Progressive charges no deductible for a repair under comprehensive coverage. Prices are in how much to repair a windshield crack, and the full decision is in windshield repair vs. replacement.

Kits and ROLAGS cover laminated glass only. AAA found laminated glass outside the windshield on about a third of 2018 models, and a side window’s corner label names its type. For side windows, read can side glass panels be repaired.

Storing a kit and handling the resin safely

Store an unopened kit in a cool, dry place. The Permatex data sheet gives a storage range of 46°F to 82°F (8°C to 28°C) and says the lower half of that range is best. It also says not to pour unused resin back into its container, because that can contaminate it. The Rain-X kit holds a 1-gram bottle of resin, and the Permatex kit holds 0.025 fl oz (0.75 ml).

The resin can irritate skin and eyes. The Permatex safety data sheet says it causes skin and serious eye irritation and may cause an allergic skin reaction. The sheet calls for protective gloves, eye protection and a well-ventilated or outdoor work area. It also says to store the product locked up and tightly closed. Rain-X’s product page carries a California Proposition 65 warning for naphthalene.

Frequently asked questions

Sources

• Rain-X Windshield Repair Kit directions (600001), chips and cracks (checked 24 October 2026)
• Rain-X Windshield Repair Kit product page and Rain-X FAQs (checked 24 October 2026)
• Rain-X: Windshield Repair Kit UV light requirements (updated 8 April 2026)
• Permatex Windshield Repair Kit (09103) product page (checked 24 October 2026)
• Permatex Windshield Repair technical data sheet (revised March 2014) and Permatex 09103 safety data sheet (revised 19 August 2025)
• ANSI/AGSC/NWRD/ROLAGS 002-2022, Repair of Laminated Automotive Glass Standard (checked 22 October 2026)
• Safelite Help Center: glass damage and service and Safelite windshield repair
• Nationwide: can a cracked windshield be repaired
• AAA: how much does windshield repair or replacement cost
• Progressive: glass repair vs. replace
• AAA: Vehicle Escape Tools research report (July 2019) and AAA newsroom release