Curing Windshield Repairs: Why Cures Fail and What to Cure With

A repair that looks right when the resin goes in and wrong an hour later failed at the cure. Either the resin did not get enough of the right light, or the pit was open while it hardened, or it was the wrong resin for the temperature before the lamp ever came on. This guide covers what GT Tools sells to cure with, what each piece costs, and the five things to check when a cure comes out soft, cloudy or incomplete.

How Long a Cure Takes

GT Tools publishes a cure time of fifteen seconds for the DarkCure™ system. The number most often quoted in the trade is far higher.

Two different numbers appear on the product page and they measure different things. The cure time is 15 seconds. The lamp's cycle is 35 seconds, because the tool runs a fixed cycle and then shuts off by itself. The extra twenty seconds is margin. GT Tools' instruction text says a single cycle should be enough for most windshield repair resins and that additional cycles do no harm.

If you have been holding a lamp over a repair for a minute and a half, well, you can get a little time back!

What GT Tools Sells to Cure With

GT Tools' current curing hardware is LED. The older bulb-type UV lamps are covered at the end of this guide, but they are not typically what a shop buys now.

The standalone lamp

The DarkCure™ Extreme UV Rechargeable LED Curing System is $205.00. GT Tools describes it as the most powerful windshield repair resin curing system available. The box contains the lamp, a charger and the manual.

Four numbers from the page that matter on the first day:

• The cycle is 35 seconds, fixed, with an automatic shut-off.
• A full charge lasts roughly 300 curing cycles. The product description puts it at up to 350 repairs per charge.
• The first charge takes 2 to 3 hours.
• Only the supplied DarkCure charger works with the tool. Other chargers will not.

The indicator on the side of the lamp turns orange when the charge is low. A replacement DarkCure™ 110V/220V to USB-C Wall Charger is $48.30.

Curing built into the bridge

On the VANISH system the lamp is part of the bridge rather than a separate tool, so there is one item to carry and one thing to charge. The VANISH™ DarkCure™ Extreme UV Bridge and Lamp Assembly is $501.90 as a replacement or as a second assembly, and its USB bridge charger and cable is $48.30.

Which arrangement suits you is a mobile-versus-bay question. Integrated curing is one fewer thing to lose on a driveway. A separate lamp lets you cure one repair while the bridge is already set on the next, which is worth more in a bay running repairs back to back. Our comparison of which repair system fits which shop covers how the three GT Tools systems differ on this and on everything else.

Eye protection

GT Tools' instruction text opens with it: always wear UV eye protection when using the DarkCure lamp. DarkCure™ UV Protective Glasses are $14.70. Buy them with the lamp.

Why a Cure Fails

Five checks, from least time-consuming to most.

1. The lamp is low on charge

The orange indicator is the signal, and it is easy to miss because nothing else changes. A lamp late in its 300 cycles still lights and still completes its full 35 seconds. Charge it and cure the repair again.

2. One cycle was not enough

A single cycle covers most windshield repair resins, which leaves the ones it does not. Additional cycles cause no harm. On a deep pit, a long crack or a cold windshield, run a second cycle before you scrape anything.

3. The wrong charger

Only the charger supplied with the tool is going to work properly. A lamp on a generic USB-C charger can sit on the bench overnight and come off it just as dead as when it went on. If a lamp will not hold charge, check the charger before you conclude the battery has failed.

4. The resin was wrong for the temperature

This is the one that shows up as a repair that cured but does not look right, and the cause is upstream of the lamp. GT Tools publishes temperature guidance on the DiamondClear range: low viscosity below 60F, high viscosity above 85F. A resin used outside its range flows differently going in, so the break is not fully filled when the light arrives.

The full range is six viscosities at $39.00 for 15cc and $69.00 for 30cc: low, medium and high viscosity, a long crack resin, and two pit fillers. Our guide to choosing repair resin by damage type maps each one to the damage and the conditions, and it is the guide to read if cures are failing more in one season than another.

5. The pit was open during the cure

The curing film goes over the filled pit before the lamp does. GT Tools sells two. Mylar Curing Squares are $7.40 for 25 or $18.90 for 100. Pit Tape For Curing is $7.40.

Both are consumable and both are cheap. At $18.90 for 100 squares the film on a repair costs under twenty cents.

Finishing the Pit

After the cure, the pit gets filled, covered, cured again and scraped flush. Pit Gloss is $10.50. Two of the six DiamondClear resins are pit fillers, at the same $39.00 and $69.00 as the rest of the range.

The Large Pit Adapter at $34.70 fits the injector over a pit too wide for the standard opening.

The customer runs a fingernail over the pit, so that is where the repair gets judged. Our guide to discs, grit order and polishing compound covers glass polishing in full, though a repair pit is a much smaller job than a scratch.

What the Curing Stage Costs

Item	Price	Reorder?
DarkCure™ Extreme LED Curing System	$205.00	No
DarkCure™ UV Protective Glasses	$14.70	No
DarkCure™ USB-C Wall Charger	$48.30	Replacement only
VANISH™ DarkCure™ Bridge and Lamp Assembly	$501.90	No
Mylar Curing Squares	$7.40 for 25, $18.90 for 100	Yes
Pit Tape For Curing	$7.40	Yes
Pit Gloss	$10.50	Yes
Large Pit Adapter	$34.70	No

Prices checked 24 September 2026. Confirm current pricing on the appropriate product pages.

A first curing setup means the lamp at $205.00, the glasses at $14.70 and 100 curing squares at $18.90, which comes to $238.60 and enough film for a hundred repairs. Add pit gloss at $10.50 and the working total is $249.10.

Against that, a technician already running a VANISH has the lamp in the bridge and needs only the consumables.

A Note on the Older UV Lamps

The GT Tools UV Lamps and Bulbs collection still lists the 12 Volt UV Curing Lamp and the replacement bulbs from the generation before LED. Those are not currently available to order. The 110 Volt to 12 Volt Adapter at $18.00 is still stocked for anyone running one.

If you are buying a curing light now, buy the LED unit. There is no bulb to replace and no cable to run to a vehicle battery.

Frequently Asked Questions

How long does it take to cure windshield repair resin?

GT Tools publishes 15 seconds for the DarkCure™ Extreme LED system. The lamp itself completes a fixed 35-second cycle and then shuts off on its own, which covers most windshield repair resins with margin. Running a second cycle causes no harm and is the first thing to try on a repair that has not hardened through. A minute or more is not required with an LED unit.

Why won't my windshield repair resin cure?

Check the charge indicator first, because a lamp low on charge still completes its full cycle and gives no other sign. Then run a second cycle. Then confirm you are using the charger that came with the tool, since no other charger works with it. If the resin filled poorly before the lamp came on, the cause is upstream: the wrong viscosity for the temperature, or a pit left open during the cure.

Why does my windshield repair look cloudy after curing?

Cloudiness points at the fill rather than the lamp. Check whether the pit was covered with a curing film or pit tape while the resin hardened, whether the resin suited the temperature, and whether the break was completely filled before curing started. The published range is below 60F for low viscosity and above 85F for high viscosity, and resin used outside its range flows differently going into the break.

What is the difference between LED and UV curing?

Both cure resin with ultraviolet light. The difference is the source. GT Tools' older lamps used a replaceable bulb on a 12 volt supply. The DarkCure™ system is a rechargeable LED unit with no bulb, no cable and a fixed automatic cycle. GT Tools' current curing lineup is LED throughout.

Do I need a separate curing lamp if my system has one built in?

No. On the VANISH system the lamp is part of the bridge assembly. A separate lamp is worth having where you want to cure one repair while the bridge is set on the next, and it is what you need if your bridge has no lamp in it.

How many repairs does one charge cover?

Roughly 300 curing cycles per charge, and up to 350 repairs according to the product description. The first charge takes 2 to 3 hours, and the indicator turns orange when it is time to charge again.

Can I run a curing lamp from a van?

A rechargeable LED lamp removes the question entirely, since there is nothing to plug in. GT Tools still stocks the 110 Volt to 12 Volt Adapter at $18.00 for the older lamps, but those lamps are not currently available to order.

How much does the curing stage cost to set up?

The lamp is $205.00, UV glasses are $14.70, and 100 Mylar curing squares are $18.90, which comes to $238.60 for a complete first setup. Pit gloss at $10.50 takes it to $249.10. After that the ongoing cost is film and pit filler.

Browse curing lamps, films and pit supplies in the UV Lamps and Bulbs collection, or reach the team at gtglass.com.