Surface and subsurface crack

[tooldini]

I am having problems with small cracks. How can I tell easily if they are surface or subsurface cracks? I flexed from they inside and they seemed to close up. I thought I could feel the crack with a razor blade on the outside but it seems flexing from the inside would not close them. This is starting to bother since I have had plently lately that have small crack about .5 to .75" long off to the sides. Any help guys?

thanks
Jeff

[GlasWeldTech]

I would think if you flexed from the inside they would open up? I SLOWLY drag a corner of a razor blade over the crack and if it is to the surface it will catch or drag it.

[tooldini]

thats exactly what I thought,, I guess its possible I ran the blade over a small partical of dirt or something. The crack seemed to be gone at some angles but pretty visible at others. If done properly shouldn't it be a hair line from any view? If it matters I use glasweld provac 2000. I didn't seem to have an issue until lately must have gotten lucky or something thanks for the replay glasweldtech

Jeff

[GlasWeldTech]

I always drag my blade over several spots to be SURE it is surface or subsurface. Finished it should look like a fine hair inside the glass. On cracks I use the older pro vac instead of the newer pro vac 2000s that I have. This is just a personel preference as it is what I trained with. I did get a new dvd from another company, ( I will not mention any names due to respect for Jeff's sight here), that shows them drilling to the laminate and using only crack jacks to open the crack from the inside and filling the crack right out of the bottle (no injector used) and covering with a roll of tape and curing. I haven't tried this method yet but will try on a practice glass and see how it goes. I always drill and pop a mini bull and fill to anchor the crack. I fill from the point of impact and know others do just the opposite. Hey, whatever works and the customer is happy.

[tooldini]

Thanks,,
these were just small crack that extend from the half bullseye. I guess I probably should have drilled well it didn't look terrible and she was still happy with it.

Jeff

[GlasWeldTech]

TOOl,
Sounds like you did right. I only drill and pop if they are on the surface.

[tooldini]

I hope, just seemed odd that at a couple angles the small cracks very virtually invisible but at another you could see them pretty good I felt. I guess it just confused me that flexing from inside the car made them almost invisible LOL damn been really learning alot the more busy I get. I guess thats good and glad you guys can help me out.

thanks
Jeff

[Mike Allen]

I have noticed that cracks to the inner lite will look darker when looked at from the outside.