Hi Guys I need Crack Repair 101

[jonnyques]

Hi I need some info on how to do cracks. Firstly I am interested in the aprox 4 inch verity that stem from a bull or star. Ive done some stars this past week that had these cracks. Truth is Im not sure if they did infact fill. When looking at a sharp angle I can see the resin flow in the crack. I identify this as the black turning clear. Flexing will get rid of black left behind. Ive found it works better if I run resin over the top of the crack and keep moving dripping resin back up onto the crack during the repair. I have tried to cure under preasure, about 5 min before removing the bridge. Should I cure longer? or how do you tell if the resin has cured in the crack? ( I know how much light , cloudy day etc I just feel 5min should be ample, am I wrong?) Flex it and see if there is movement in the resin?
I HAVE NOT used curing tabs or tape over the crack just on the pit. Should I be using it? Do you coat the crack in resin or pit sealer then apply tape? Iam asking this because after I remove the bridge after what I feel is my preasure cure, and inspect the crack it looks like I may have loss some of the resin in it. I have also tried using 2 bridges on the crack and adjust the seal preasure on the crack incase Im closing it up. Ive also used heat. I do not have a crack expander, should I get one for these small cracks? What length do you need one?
What should the finished results look like? What can be expected on a crack? On certain angles they look clear (no black) but you CAN tell that there was still a crack there. Is this normal? Resins, I know delta says theres is fine, and thats what Ive been using. Looking on some sites they list a resin FOR cracks. I notice that the cps is always higher than 40. Do you want a thick resin? I would think you would like a thin resin (20cps) to flow in the cracks. Do you use different resins on different cracks? I would say some cracks appear very tight while some look as though there is a void between them. Any insite or general rules things to try do etc would be great. Again Im not looking at cracked out shields maybe a max of 6"
Thanks

[scratchy]

Almost all cracks 6" or less are easy. Most are fresh too. Make a fresh mini bulls eye right off the end of the crack and watch the crack jump into it. Mount injector over the mini BE and mount an injector over the chip which cracked out. Put both on a pressure cycles. Install a crack jack gently on the inside glass between the two injectors and tighten up gently! Give just enough pressure to open the crack up enough for resin flow. Using a cappilary method flow resin from the bottle over the crack, laying down curing strips. Now, cure thoroughly and clean it up just like a chip. I use a 24" curing lamp and a power pack almost exclusively.

[jonnyques]

I take it then that it is important to cover with tabs / tape as the crack fills? This is something I havn't done. I guess Ill have to order a crack expander. Do they work ok on cracks that have curves in them. I guess the crack has to be in a location where a expander can be used. I see alot it seems close to the edge. Thanks for the input... lots of good info
John

[screenman]

Scratchy is spot on here.

You need to use curing tabs because quite often the top of the crack is open to air and we do not want any of that when curing. I personaly do not use a crack expander but I think they can be a good idea I tend to just push the glass by hand from inside the car if the resin starts to stop flowing I find this gives me more control.