Air spot on repair

[Mr Bill]

Yesterday I did a repair. At the start it looked like a regular no drill bullseye. After removing the injector from the repair, I noticed a black air spot on the chip. When I flexed the glass, the air spot just moved and eventually got bigger as more air got into the break , so I had to put the injector back on and inject a little more resin. So then I was back to having the air spot which caused the problem in the first place. I ended up drilling and popping, but I got a little spider web crack at the point where I popped, not the normal bullseye , so then I had to fill the spider web. The customer was happy, but I felt that I could have done better.
What is the correct proceedure in a case like this?

[Dependable Dave]

Mr Bill, It sounds like you are taking the injector off before curing the resin. Try curing it under pressure. Maybe what's happening is the surface of the damaged area is springy and pops up when you take the tool off, sucking air back into the break. If you look carefully (I use pretty strong reading glasses to compensate for my old eyes), you can see the onionskin-like layer of glass on the top. It will flex very easily when you press on it with your probe. Imagine how much pressure is on it when you tighten down your injector. The pressure squeezed the onionskin layer down. If you cured in this position, with the injector in pressure mode, the black spot will probably not appear.

[Mr Bill]

Thanks for the reply, Dave.
I use a Delta Kits injector and I don't believe that they recommend curing with the injector still in place.
Any suggestions on how a Delta Kits user would tackle this problem?

[GlasWeldTech]

Have you taken Delta's training class? I would call Mr. Jeff Higgins ASAP.

[Mr Bill]

Yes I took the Delta Kits training class.
I did not encounter this particular type of chip at the class.
I have noticed that every chip has its own personality. No two are exactly alike, even though at first glance they may resemble a previous repair.

[maxryde]

Was the bubble "sticky" did it want to return to the same location each time? What you describe sounds to me as though it may be a contamination issue. The resin is designed to etch the glass for bonding purposes. Rain-x and the like when introduced to a chip will cause this kind of reaction, as well as some other contaminates. It then will stop the resin from wetting the area and the air will stick more redilly than the resin to the contaminated area. When I was new to the car business I knew a few dealers who would put ATF in a chip and it would disappear!!! Problem is it would reappear in a few weeks and some folks were less than happy!! But such is the used car business!!!! I do business with some of the dealers there are some VERY good people out there too!!! You never know what you'll get out there!!! Sometimes getting a history on a chip can be very informative. I did a crack on a rig today and on the phone it was very fresh when I got there the thing was very contaminated!!! OLD!!! The guy fessed up and said he was just interested in getting it fixed. So I fixed it and everybodys happy!! On that repair I could just about tell how long the first crack was on there then the new part!!! It was interesting!!

[JAC]

I took the Delta training also. I've found myself making little adjustments to the training as I gain experience. One thing I've done on the air issue is I've gone to 3 cycles. On a small bullseye I'll still do 5 minutes injection, 30 seconds vaccuum, 3 miinutes injection, 30 seconds vaccuum, then injection and remove, cure and polish. On larger bullseys, spiderwebs, cracks, etc, I'll cut the first cycle down to 3-4 minutes, but tack on an extra 3 minute injection and vacuum at the end. It ads an extra few minutes, but I've had good luck with it.

JAC