Crack repairs

[south88]

Again some more questions for you experts. I have been trying the capillary method for fixing cracks. Results are less than perfect by far. Some parts fill in nicely, others dont, and some fill part way. I would like to try the injector slide method but have some questions on that. If someone can answer these scenarios, I would be grateful!!

1. horizontal crack with chip in the middle.

2. u shaped crack with chip on the top left.

3. vertical crack with chip in the middle.

Please answer how you would repair these, step by step. Thanks again, Jon!!!

[repare-brise]

Jon

Crack repair is something that requires one major skill, patience. Wether you use an injector or capiliary action, take your time to make sure the break is full before moving on. I personaly use the injector method with great success, but there are a few considerations that apply regardless of technique. When doing a vertical crack try if possible to start from the bottom and work up, this allows any air to rise ahead of the injector. There is no hard and fast rule as to how to proceed with the breaks you described, but I generally will fix the cracks up to the original dammage, cure the crack, then treat the dammage as a standart stone chip, I find I get the best results this way. On floater cracks I pop a mini BE at the end of the cracks, this has 2 purposes, the first is that it relieves the stress at the end of the crack, making it easyier to fill. The second purpose is to create a "block" that stops the crack.

If you have not used the sliding injector method before here are a few pointers.

- lubricate the glass with a minimal amount of petrolium jelly.
- If at all possible use the injector above the crack, this will keep you injector and base clean should some resin leek out.

[Don Boccafola]

One tip that I got years ago from good old Rock Chip Rich was to use hand cream as a cup lube for sliding the bridge. My Bridges slide good, clean up is easy and my hands get conditioned all at once.

[repare-brise]

Don

Great tip, what cream do you use? Do you have problems with it drying on the glass when hot?

Thanks

[toab]

Yvan.. I noticed that in your crack repair description you didn't mention the use of crack expanders.You do use them on occ' don't you? Oh and thanks for the hand creme tip Don...puting some of the wifes in the tool box now.

[GlasWeldTech]

I also use hand lotion for sliding a crack. I buy the cheapest I can find.

[repare-brise]

Toab

I prefer not to use crack expanders( I may use it once or twice a year, not more, and for some of my tecks it's still virgin). I prefer to use patience, an injector, and a resin that has exceptional capiliary action. But to each his/her own.

At Your Service

[Bill D]

Good info on the hand cream. I can't remember if it was GT or LR who gave me a tip. Make sure the cream is not petroleum based if your suction cups are 100% rubber, as they will break down from the oil.
I'm not a Chemist, but it has been about 10 years since I bought those cups.

[Sneck]

South88, regardless of what length or shape of long crack I am filling, I always start from the tip (the stressed end). I drill and pop a mini to releive the stress on the end of the crack, and start filling from there. Once that starts filling, the rest is easy.

It does not matter if the stress-end of the crack is up high or down low, I always make that my starting point.

Now if you have a rock chip in the middle, and a long crack coming out of each side (essentially two long cracks and a chip to fix), I still start at the stress end of the crack and fill - chasing the air along the crack and into the rock chip. Then I do the same on the other crack - chase the air along the crack and into the chip. After curing the cracks, then I proceed with standard chip repair procedures.

One side note to this...

I always do all drilling first, so the vibration of drilling a second or third hole does not re-open a crack.

In a situation like this, where you have a chip in the middle and two long cracks emitting from the chip, I drill and pop a mini at both ends of the two cracks as mentioned. I then drill the chip so that air can be chased down the cracks and into the rock chip and the rock chip can vent any air pressure that may build up from this procedure. Relieving the air pressure by drilling the chip ensures that resin will flow freely during this type of repair.