Long Crack Question

[Clearview]

:eusa_booh
Long Crack Question:
Does anyone know why when repairing a long crack that the silver line does not completely go away? On 95 % of long cracks I do either one of two thing alway occurs. Either the long crack has little specks of silver in some areas of the break or their is a fine silver line that always remains... The other 5% of the cracks that I do the line almost completely disappears except for a fine hair line. It seems that it occurs mostly on horizontal lines.

I always use a crack expander on the inside, I cover the area with my UV shade and I always make sure I do not run over the crack while cleaning the area.

Some people say it is because debris is inside the crack. Any one out there a pro at long cracks and can explain the problem.

One other short question. What type of material is most UV Shades made of?
Thanks to all.

[scratchy]

That thin silver line is a nearly microscopic air bubble. You can drill with a skinny bit down to it and inject resin to fill it without much cosmetic damage if needed.

[repare-brise]

CV

Scratchy is correct, I refrain from using crack expanders, and I use a dedicated crack repair resin and injector. I don't use expanders for the simple fact that they distort the glass, especialy if you cure with the expanders in place. For the resin you should use a resin with a strong capilliary action, it will draw itself to the bottom of the crack. Also be patient, don't move your injector untill the crack is filled to the bottom, only then should you slide your injector forward. Some cracks fill with ease and some take a while to fill, I always leave long cracks as my last job of the day if I can, this gives me the luxury of time. A side to side rack can be filled in 30 mins of could take over an hour, no way of telling until it's done.

Merci

[Bois]

Like Blind Squirrel, I'm very interested in knowing what method you long crack repair professionals use along with what type resin you find works best for you.

For the resin you should use a resin with a strong capilliary action, it will draw itself to the bottom of the crack.
Merci

What type resin do you use, Yvan?

Dale...

[Clearview]

Marci,
Where can I receive a sample of that resin with strong capilliary action?
Clearview

[Delta Kits]

The capillary method is also how we do long crack repairs, and it works great.

The problem with this statement:

I don't use expanders for the simple fact that they distort the glass

is that it's followed up with this statement:

only then should you slide your injector forward

Using a bridge and injector along a crack is flexing (distorting) the glass as well. In addition to that, that flexing can cause the break to open and draw in air where you've already filled. Most of the distance that you've filled will be covered with tape, but not right by the injector.
When doing crack repairs, the object is to fill the break while disturbing the glass as little as possible. The only time I suggest using crack expanders is if you reach a point in your repair where the resin does not want to go farther.

Crack expanders are an excellent tool, if used properly. The purpose if a crack expander is to open that break only enough to allow the resin to flow, so you don't need much pressure at all.

Long crack repair is more an art than anything else. It takes practice & patience.

To answer the original poster, hairlines are normal, but specks of silver in the crack are air bubbles.

[Delta Kits]

The problem with direct flexing, is that it will obviously flex back, which can pull air bubbles in, so I can see why you've had a problem with it.

Also, once bubbles have formed, it's very difficult to remove them. When using the capillary action, you always want to add resin where there is currently still resin. So, what I mean is, don't ever put resin into a break directly above air. What will happen, is you will almost always create air bubbles between the resin you are putting in, and the resin that is already there.

I recommend adding resin about 1/4-1/2" behind the fill line. When you add resin there, it will push resin farther down the break. If you get to a point where resin doesn't flow any further, cover what you've done and add a crack expander. Once the crack expander is in place, go back to your 1/4-1/2" mark, and try again.

The secret of long crack repair is patience. Patience to not get ahead of your 1/4-1/2" mark so you avoid air bubbles in the first place, because once you get them, you rarely will get them out.

[scratchy]

Number 1 most important thing in fixing a long crack is not length. (I hope this is taken into any future licensing requirements) Its freshness of the break. I have repaired some fresh breaks then gone and run across the customer's vehicle weeks later. Taking a look at the W/S I swore it was replaced making me think the repair blew out and they took it somewhere else for a new one. After looking really close you can finally find it. Most of the cracks, when done right and done fresh, look better weeks down the road. Amazing.

And I agree, too much crack jack causes distortion. I wish I had 8 arms, two to wick and laydown squares, the other 4 to dig around the tool box and install some jacks opening it up only if necesssary.

[sunshine wr]

I use crack jacks as a last resort, I use capillary & injector slide methods , whichever the situation calls for (sometimes its both).If injector sliding, the cups need to be slick enough so you don't flex the glass while sliding, (any flexing of the glass will cause those nasty bubbles). So stay off the ws as much as possible. If you're sliding you can go back behind air bubbles and use your injector to push them out.I also like cure tape torn in small pieces rather than tabs. The tape seems to help keep the air out better than tabs. I always put the tape down real smooth, I will hold the cure light over the crack rather than stick it to the ws as this will cause flexing too. Don't let the last thing you do mess-up all that hard work.( this method works well with my tools).

[repare-brise]

At the detriment of insulting Jeff here is the long version of how I do crack repair. I use an injector and base designed specifically for cracks, contrary to Jeff's statement, it does not flex the glass, it instead slides along effortlessly on a bed of petrolium jelly, no distortion inducing flexing of the glass. I use a resin formulated for crack repair, this resin is very thick, has a strong capiliary action, and fills even "wide" cracks without seeping out.
-Start by drilling just past the end of the crack and poping a mini bulls eye.
-Set up your regular injector on the fresh bulls eye and inject using crack resin.
-When bulls eye is full and crack has begun to fill cover filled portion with curing tape.
-Put a thin layer of pet jelly on glass above crack(or to one side).
-Remove spot injector and cover pit with crack resin and tape(slide existing tape over a little bit)
-Put crack repair base on pet. jelly(support glass from other side to prevent flexing) put appropriate amount of resin in injector and apply to glass where prevoise injection stopped.
-As crack fills slide injector along crack (keeping injector 1/8" behind filled portion) slide curing tape along behind injector, adding new tape as crack progesses.
-Cure crack with uv light as close to injector as is practical.
-When resin is cured, scrape excess cured resin from glass.

Tips for better crack repairs.
-Be patient
-If crack is not fresh, clean with high pressure washer, blow out water with compressed air(have this done by the customer a day or so before repair), allow to sit until dry.
-For vertical cracks start from bottom and work up(this reduces the possibility of trapping air in the break).
-Make sure vehicule is on a stable level surface, avoid touching vehicule, avoid opening and closing doors.
-If an air bubble gets trapped two methods can be used to eliminate them, first a small shot of heat(1 sec or less) will make the air rise to the surface(make sure you have a curing tape with resin covering crack before attempting either method, the resin will replace the air if done correctly) and be replaced by the resin on the surface. Second,slow flexing of the crack, before curing, to do this place your finger under the offending bubble, slowly add pressure, then when the bubble has risen to the surface, slowly reduce the pressure until the spot is filled.

If you have any further questions please e-mail, PM, or call me.

Merci