Flexing lines on breaks

[tntglass]

Hello I'm new to the forum. I've been doing windshield repair for about 3 years on the side. I do not have much experience in this field but would like to gain knowledge. Here are my biggest questions. I use my truck windshield for practice and I create a star break about the size of a nickel or quarter. I flex the break before I start the repair and notice some hidden lines. I assume those are sub surface lines correct?

Next I clean the impact point and apply my kit and pull vacuum for about 2 minutes. Next I switch to pressure and examine the break. I notice most of the lines are filling in and I begin to flex around the injector and notice a few new lines. What is the correct way to make sure these hidden lines are filled properly? I repeat the vacuum/ pressure cycle for about 15-20 minutes.

I've heard heat with a lighter but never have done that. Does this work?

After I have cured and scraped excess resin, I flex near the impacted point and the hidden lines are still there. I am pressing very hard on the repair. Please any information would be helpful. If I'm not doing something correct please tell me. I'm open to constructive criticism. Thank you.

[Auto Glass Rescue]

Hi and welcome I'm still also somewhat new to this, but I have to ask... Others would have asked this question, but I'll be the first - Have you had any prior training and what repair equipment do you use? The reason is you stated that your first cycle is a vacuum. With Delta Kits and their training, they recommend a pressure cycle first.

I'm sure others will be here shortly to ask more questions about you and give you more input on the other questions you asked.

Good luck and welcome aboard!

[tntglass]

I have had training from a previous business owner in the glass business. I use equipment that was custom made but very similar to most repair kits. My kits include a bridge with a separate vacuum/ pressure pump that attaches to the bridge like an air line on a compressor. For the 3 years that I have been doing repair I've had 1 repair come back as failed (that I know of at least). I currently use US WINDSHIELD REPAIR resin 20 and 40 CPS. Most repairs that I have completed clear up pretty well but I would like to improve my skills. Can you explain to me why the pressure cycle is first?

[Brent Deines]

Our recommendations are for Delta Kits equipment only. Some competitor's equipment are designed to start with vacuum so you should always follow the MFG instructions.

[Mr Bill]

You shouldnt have to press on the glass very hard to flex it.
I personally would be afraid to press hard.
Suppose you had an unstable chip and it cracked out?.

[screenman]

The idea is to press hard enough to get them to open nicely, but not hard enough for them to run, your eye's should tell you when to stop pushing.

If the legs are still there after you have finished the damage has not been repaired. Try using less pressure on the injector seal.

[tntglass]

Ok I will try less injector pressure. Have you guys heard of putting pit resin on the stubborn lines and pull vacuum then heat with lighter? I heard this through another company in the area. I don't believe it would word if its not a surface crack correct? Thanks.

[screenman]

Pit resin normally a thicker resin so will not flow well. The muppet that said heat it up, did they tell you to let it cool for an hour before curing. As without a heat sink it can take this and longer before that area of glass you have heated cools back to its ambient temperature.

Poorly trained people often get confused about legs that have shut up due to glass expansion through heat, and those legs filled through resin flow.

Make a nice size star break heat until the legs disappear and the see how long it takes to cool back down and all those legs to reappear, we have sometimes found even overnight is not enough.

One way we have found to open a leg on a warmish day is by using the heat sink, this causes the glass to shrink and the leg to get wider.

[bill lambeth]

Heat is a last resort for me.I very rare have to use heat to get a star to fill.You must be patient.Most rookies have to much barrel pressure which will not allow it to fill