Hmm. I've bottled a porter with out any issue, and currently have an IPA and a Milk Stout bottled in growlers using poly seal caps and electrical tape. I'm curious about the IPA cos it's a 6.8abv. We cracked the porter while bottling the IPA and it was fine. Actually a little sweet still like it wasn't quite done, but the carbonation was on point with the rest of the batch. Unless I have the space to keep one aside, I don't think I'll try bottling anything over 8% abv. But who knows. So far, it's been fine. Now, I have to ask. Who in their right mind uses clear growlers? Knock it off!