Bottle neck - thread inside

I’m currently redesigning a beer-bottle. I’m looking at various options for a new type of top, and I was wondering if it is possible to have a thread inside a bottleneck. I know this is (much?) more expensive than to have a thread outside, but I want to look at this option anyway. Is it possible to twist a glass bottle from the mold after the blowmolding?

thanks in advance for any help!
Charissa

Soda/beer bottles are molded in two steps. First, a preform which looks like a test tube with a threaded top is injection molded. Then, that preform is blow molded into the final shape of the bottle.

The reason for the two-step process is that injection molding is needed to guarantee that the threads will seal. Pure blow molding can’t achieve that tolerance. Check this explaination out:

http://engr.bd.psu.edu/pkoch/plasticdesign/Blow_Molding.htm

You might be able to get a molding like that with either a really careful de-molding step, or a lot of mechanical slides in the mold tooling, but it would be really costly. So unless you using it to solve a really high value problem(as opposed to just making it different for difference’s sake) I’d say it wouldn’t be worth the trouble.

plus if you have a glass bottle there is a risk of the threads breaking/chipping off and contaminating the contents.
What’s wrong with a cork?