abracadabra! where did the air go?

[Glass Doctors UK]

OK guys, here is a question that i have never been able to adequately explain and have never fully believed what i have been told about it either.
i am really interested to hear other peoples theories on it...

...when you are repairing a star and the leg is under pressure and the resin is flowing down the leg in a perpendicular wave...

Where does the air go?

you let the pressure off and it still completely fills the leg without the air expanding back to fill the end of it.

I dont mean those legs where you can see the trail of air crawling back along the bottom either, just the ones where it goes straight to the end at 90 degrees to the laminate and stays.

[wilz]

What system do you use?

[wilz]

What repair system do you use?

[Glass Doctors UK]

i could say but i dont want to divert from the main question really as i think the question is the same for any kit.

[mafsu]

The air is still escaping around the resin. The kind of leg you are talking about is just open enough that the air can escape beside the resin. This makes it virtually impossible to see. The type of filling you are talking about only happens in a tight leg when it is flexed open. As opposed to the usual method of escape in a tight leg that you mention where the air escapes above or below the resin. This is hard to explain without visual aids.

[splitpit]

Is there a cure for visual aids?

[Fireball311]

Is there a cure for visual aids?

Now thats funny I don't care who you are. I have been wondering the same thing with the air in the leg.Great question.

[ChipRite]

If the leg is open to the surface, the air is pushed out ahead of the resin and if you have the injector on pressure and carefully watch the leg fill you may even sometimes see tiny beads of resin pushing out on the surface of the crack. Problems start when the crack or leg is subsurface.

[Glass Doctors UK]

Thanks for the reply Chiprite but i am talking about a sub surface leg and not one that has broken the surface.

[Glass Doctors UK]

The air is still escaping around the resin. The kind of leg you are talking about is just open enough that the air can escape beside the resin. This makes it virtually impossible to see. The type of filling you are talking about only happens in a tight leg when it is flexed open. As opposed to the usual method of escape in a tight leg that you mention where the air escapes above or below the resin. This is hard to explain without visual aids.

Thanks for the reply Mafsu, the type of filling i am describing happens on all normal crack legs not just ones that you have to flex to open. I dont think it is the right explanation for the following reason:
when we inject a bullseye and then pull a vacuum afterwards, we can see the air go back to the entry point even though it is travelling back around the resin as you say, and i would expect us to be able to see the resin being displaced in a similar way down a star leg too. We know when this is happening in a star leg because we can see air sometimes travelling back along the bottom of a leg quite distinctly yet not when it is just flowing up a leg as i have originally described.