Air bubble (outgassing)

[timgrreen]

When drilling I use a 1m dremel bit, if I need to drill a repair to prep it for injection.

If I leave it as a straight drill hole (cylindrical in section) I always get an air bubble that forms in the drill hole during curing. I always make sure that there are no air bubbles when I apply the pit filler, and before placing the curing lamp. Still a bubble forms. I'm proud of my repairs otherwise but this glitch is really annoying.

To get around it I now cut a groove along the opening to the damage with my dremel. Not ideal as it means a bigger patch of pit filler.

Any ideas?

Tim G

[screenman]

Tim here is a couple of ways we find that that help do away with air bubbles.

1. Make sure that you are not drilling upwards, you need to be at the least totally perpendicular to the glass with your drill when drilling.

2. When you first open your toolbox at the job turn the pitfill upside down.

3. Never let air suck back through your pitfill bottle, after you have squeezed out the required amount turn the bottle top up and let the resin settle back down in the bottle before releasing the squeeze.

4. You can try a trick we sometimes use, place the pitfill in the pit and cure for a couple of minutes before placing the tab on it, in fact often it is so hard that you do not need the tab, now this makes scraping slightly harder as the surface is not so flat, we feel that this method helps any air to evacuate the pit whilst curing.

5. Make sure the damage is properly back down to the ambient temperature if you have used heat at all, we have cured hot repair to see what happens, when it cools down air pockets can appear quite dramatically.

6. When all else fails keeping your fingers and toes crossed has been known to work.

[Nomad]

A few years ago I had a lot of trouble with bubbles in the pit but that was because I was using a new pit filler that was too thick, at least for me. It would bridge the hole and leave a bubble. If Screenman is right then you need to be very careful about getting air entrained in pit resin. I have had air in resin before and if you can figure a way to put a vacuum on it it will pull the air out. Maybe put some in a syringe and pull the plunger back with the end plugged?

This is why I like to pull a vacuum on the filled chip for a bit. I think it helps pull any entrained air out of the resin, if there is any in there. Also, I don't wipe the resin from the pit before applying the filler. That may help too.

Otherwise I think Screenman covered all the bases.

Let us know if any of this helps.

[timgrreen]

Thanks for the help, will try and de gas the resins for sure but they are all helpful suggestions.

Tim G

[WW973]

When drilling I use a 1m dremel bit, if I need to drill a repair to prep it for injection.

If I leave it as a straight drill hole (cylindrical in section) I always get an air bubble that forms in the drill hole during curing. I always make sure that there are no air bubbles when I apply the pit filler, and before placing the curing lamp. Still a bubble forms. I'm proud of my repairs otherwise but this glitch is really annoying.

To get around it I now cut a groove along the opening to the damage with my dremel. Not ideal as it means a bigger patch of pit filler.

Any ideas?

Tim G

hey whats up man i suggest using your probe and placing it into the drill hole in the glass and pouring pit resin on and play with it a bit then after the hole is filled with pit resin place mylar over and cure as usual it works for me i get no bubbles

[screenman]

Another thought on this, make sure you are not drilling upwards, you must be at right angle to the glass or even very slightly down.

[Dr.Chipster]

Are air bubbles more common in cooler weather? I can't ever recall an air bubble while using pit filler resin. I never turn my bottle upside down until I am ready to use it. Just a question.

[Nomad]

Are air bubbles more common in cooler weather? I can't ever recall an air bubble while using pit filler resin. I never turn my bottle upside down until I am ready to use it. Just a question.

If the viscosity increases because it is cold i would think it could be more common. I also use a probe, most times the slide hammer tip, to pull any bubble out of the pit and to one side, then quickly cover with mylar tab and cure.