I agree here. I have a robart paint shaker that I used on some of my Vallejo paints -- a couple of them were shaken so much, that it took a couple of weeks to get the air out of them. However, if you have decided them while the bottle is inverted, you can get a lot of air out of the hit, and get a pretty creamy mix for brushing. If you're going to use something like this, I recommend only shaking them for approximately 2-5 seconds. Doesn't sound like a lot, but when you are shaking a bottle at ~5000 reps a minute, it can be significant.