Cracked or broken glass is an annoying and often dangerous problem. Before replacing the glass, many people try DIY repair kits that claim to fix cracks and prevent them from spreading. But do these cracked glass repair kits really work?
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What is in glass repair kits?
Glass repair kits contain a liquid resin formula designed to penetrate into tiny cracks and flaws in the glass. Many kits also include tools to help inject the resin into the cracks. Here are some of the main ingredients and components:
- Resin – The main active ingredient is a clear, liquid adhesive resin that hardens to create a strong bond. Popular resins for repair kits include silicone, epoxy, acrylic, or UV-cured resins.
- Curing agent – This helps the resin harden. Some use UV light, while others contain a chemical hardening agent.
- Injector – A specialized tool to let you inject the resin deep into cracks and flaws on the glass.
- UV light – Some kits use UV-cured resins that require a UV light tool to cure the resin.
- Razor blades or picks – For removing excess resin after application.
- Polish – A polishing compound may be included to buff out any residue or haze.
- Suction cups – To help hold the glass steady while injecting the resin.
How to use a glass repair kit
Using a DIY cracked glass repair kit is a multi-step process. Here is a general overview of how to use one:
- Clean the glass thoroughly around the cracked area to remove dirt, grease, or debris left in the crack.
- Place suction cups around the crack to hold the glass steady.
- Use the injector tool to drip resin carefully into the crack, filling it fully.
- Spread the resin using picks to remove any air bubbles and ensure it penetrates fully.
- On UV-cured resin, shine the UV light on the area to harden it.
- For air-cured resin, allow the recommended time for it to set.
- Once set, use a razor to scrape off any excess dried resin.
- Polish and buff the area to remove residue and restore clarity.
It is important to follow all the manufacturer’s directions closely when using any repair kit. The curing times, amount of resin used, and tools may vary between products.
What types of damage can they repair?
Glass repair resin is designed to fix minor flaws and cracks in glass. Here are the main types of damage these kits can be used for:
- Small cracks – Thin spiderweb cracks less than 12 inches long can often be repaired.
- Chips or pits – Small dings and chips from impact damage can be filled.
- Flaws – Minor imperfections like bubbles or uneven areas in glass.
- Holes – Repair kits may work for holes up to 1/4 inch in diameter.
The resin bonds to the edges of cracks to essentially glue them together again. Kits are not designed to repair large cracks, shattered glass, or holes and gaps too large for the resin to bridge effectively.
Does cracked glass repair resin really work?
When used properly for small cracks and chips, many homeowners have success with DIY glass repair kits. The adhesives penetrate cracks to rebuild strength. However, there are some downsides to be aware of:
- The repair is not as strong as original glass.
- Repaired areas may look cloudy or distorted.
- Kits don’t work well for cracks larger than 12 inches.
- Repairs may not last long-term.
- Resin does not restore the original glass strength or structure.
For car windshields, repair kits can be effective to pass vehicle inspections after a small crack. But for severely damaged, large cracks, or long-term use, glass replacement may be the better option.
When glass repair resin works best
DIY repair kits can offer an affordable short-term fix in some situations. Here are the cases when using repair resin is most likely to be effective:
- Very small chips or pits in glass
- Minor dings from small objects hitting the glass
- Small cracks less than 6 inches long
- Slowing crack growth temporarily
- Flaws and bubbles in glass
- Holes less than 1/4 inch wide
- Getting broken auto glass to pass inspection
Problems to be aware of
While glass repair kits have their uses, there are some potential problems to be aware of:
- Repaired areas may have cloudy appearance
- Resin does not match the strength of original glass
- Repairs may not last long-term
- Only works for small cracks and chips, not major damage
- Takes skill and precision to inject resin properly
- Repaired glass is more prone to re-cracking
- Kits don’t work well for cracks over 12 inches
Types of glass repair kits
There are a variety of DIY glass repair kits available. Here are some of the main types:
Liquid resin kits
Liquid resin kits come with an adhesive resin formula and injector tool. Popular resin choices include:
- Epoxy – A two-part epoxy cures when mixed. Provides a rigid bond but can yellow over time.
- Acrylic – Acrylic resin is often used for plastic as well as glass repair. Bonds well but can lack long term durability.
- UV-cured – Resins cured with ultraviolet light provide fast hardening without mixing. Often used for auto glass.
- Silicone – Flexible bonds and ability to resist temperature changes make silicone a good glass repair choice.
Liquid resin pros and cons
| Pros | Cons |
|---|---|
| – Fast repairs | – Messy application |
| – Low cost | – Fumes while curing |
| – Easy to find | – Can yellow or cloud over time |
| – Various resin options | – Requires skill to inject properly |
Pre-mixed putty bars
Putty-based repair kits come with a pre-mixed putty you apply by kneading and pressing into cracks. No mixing or injecting required. The putty cures with exposure to air.
Putty bar pros and cons
| Pros | Cons |
|---|---|
| – No mixing | – Harder to force into small cracks |
| – Easy application | – Not as strong as liquid resin |
| – Fast repairs | – Can fall out of cracks |
| – Minimal tools needed | – Messier and less precise |
Suction cup kits
Suction cup repair kits rely on strong suction force to pull cracked glass edges together before applying adhesive resin. This can provide stronger repairs than resin alone.
Suction cup repair pros and cons
| Pros | Cons |
|---|---|
| – Pulls cracks together before filling | – Suction can damage glass |
| – Provides stronger repairs | – More expensive |
| – Works on some larger cracks | – Requires smooth, flat glass |
Tips for success with glass crack repair
While DIY glass repair kits have limitations, following some best practices can increase your chances of success:
- Use on clean, dry glass only. Grease and dirt reduce adhesion.
- Apply resin slowly to let it fully penetrate cracks.
- Spread resin evenly and remove air pockets for best results.
- Limit repairs to cracks under 12 inches long.
- Match curing times to resin directions.
- Buff and polish smoothly to avoid clouded areas.
- Consider reinforcing repairs with clear packing tape on both sides of glass.
- Use as a temporary fix only, not a long-term glass repair solution.
Conclusion
Small DIY glass repair kits can provide an affordable short-term solution for minor cracks and damage. The key is using them properly within their limitations. While the resin can penetrate and bond cracks together, results and longevity will be limited, especially compared to professional glass replacement. But for small chips, short cracks, or just to get broken auto glass through an inspection, they can offer an easy fix.