And Speaking of Punts -- Does This Mean Anything?
I happened to notice that on the punt of a bottle of sparkling Riesling I was pouring, there was a white "smudge" that might have been paint. I wasn't sure whether it was put there deliberately or if the bottle accidently came in contact with some white paint. For what it's worth, the Riesling is Ratzenberger Brut.
Does it "mean" anything, like anything important, to the consumer? No.
Some wineries will put a small white stripe, or smudge, of paint on the uppermost left- and right-hand bottles on a riddling rack as a way of monitoring which direction the bottles on that rack were last turned. (They alternate directions with each turn.) So, probably, your bottle was one of those two . . .
Some other wineries, however, put them on every bottle just because they think it looks "cool," but that's a lot of work . . .
Hm-m, I've not seen this on any whites, and on few reds. I associate the whitewash with Port, to indicate the orientation that it has been stored in, for help in the removal of sediment. Interesting to know.
With the exception of my Ports, I always store the bottles label up, so I know the orientation. With Ports, it's the whitewash stripe.