Do Cracked Windshield Repair Kits Work?

A woman had bad luck while driving a rental car recently. A rock hit the windshield, leaving some minor damage.

Rather than risk getting charged by the rental company, she fixed it herself with a $20 repair kit.

TikTok user Kat (@kat.loissa) posted a video that shows her using a Permatex Windshield Repair Kit to fix her rental car’s windshield.

“Of course a rock would hit our rental car on the freeway,” Kat says at the start of the video. “So let’s try to fix it.”

Her post has 6 million views as of this writing.

How to Use a Permatex Windshield Repair Kit

The first step is using a thumb tack to remove excess glass and debris from the crack. The person helping Kat reminds her to go “gently” on this part. Kat’s second task is to wipe the area clean with an alcohol pad, which she also demonstrates.

After preparing the area, Kat places a red sticker around the crack, ensures that it’s completely adhered, and then removes the top red layer. She then puts a small grey funnel over the sticker.

“Now put the grey funnel also facing up,” Kat says. “Fill the hole with resin until it’s visible at the top.”

After that, Kat inserts a syringe-looking contraption into the funnel, which is used to remove air bubbles from the resin.

“Insert this and pull up to suck out the air for 20 minutes,” Kat says. “Lightly tap to help air bubbles out and remove after 20 minutes.”

Kat then puts the syringe back into the funnel and pushes air into it for another 10 minutes. “Remove carefully and use a blade to remove all stickers and resin,” Kat says. “Once clean, use more resin to fill in any cracks and place the clear cover [over the crack] for 15 minutes in the sun.”

Once the resin is dry, Kat uses the blade to scrape the cover and remaining resin off of the windshield. “Do not pull it off,” she says. “Only scrape.”

Finally, Kat cleans the area with another alcohol wipe and shows viewers her results. She also notes that the kit is available for $20 at AutoZone or $5 on Amazon.

 “Worked like a charm,” she writes in the caption.

‘Saved Yourself a Couple Hundred Bucks’

People were largely impressed with Kat’s initiative and technique.

“Nice,” wrote one person. “You saved yourself a couple hundred bucks.”

A second wrote, “You’re really that girl, because I would’ve cried, lol.”

Someone else said, “Rental employee here. Good for you.”

However, not everyone was so positive.

“By the way, this doesn’t do anything,” wrote one person. “It just fills in the crack to hide the damage, but the window is structurally weaker so it will break quicker now.”

Do Windshield Repair Kits Work?

According to Glass Solutions, windshield repair kits do work, but like anything, they come with pros and cons.

When used for small cracks like the one in Kat’s video, the kits should work to stop the crack from spreading. But how well the kit works will depend on the initial damage, the brand of the kit, and—ultimately—how good of a job the person using the kit does.

Using one of these kits won’t make your windshield as strong as it was before the break.

That might not be a concern for Kat, however, as she was fixing a rental car windshield.

Motor1 reached out to Kat via TikTok comment and email for comment. We’ll update this post if she responds.