we just corked a screw top wine bottle with no problem what so ever. we also uncorked the bottle with no issues at all. We will definitely be corking larger amounts of screw tops in the future! Thanks to everyone for the great advice on this topic as well, happy winemaking!
Using a coin reasonably smaller than the 18.5mm diameter to reduce the pressure and spread out the force over a larger area is another hack.
Being involved with the AHA and having judged national finals several times, I can tell you there are 2 concerns...first, there should be nothing on the bottle to identify it came from you. That's not too difficult. But with the number of entries we get these days, storage is a concern. The reason you should use standard 12 oz. bottles and caps is so that ...
If you can order this large a quantity, you can get custom corks in bulk from WidgetCo.
The CorkStore also has different styles of corks.
In general, craft stores will have corks, but you'll have a harder time finding the exact size you want for your bottles.
I just bought a Portugese Floor Corker, and find corking to be a lot easier than bottling. Initially, I was soaking my corks in Star San but that was causing infections-- I recommend you do not soak your corks in anything before corking your bottles.